WorldWideScience

Sample records for cell renewal systems

  1. Structure and function of stem cell pools in mammalian cell renewal systems

    International Nuclear Information System (INIS)

    Stem cells play a key-role in the maintenance of the equilibrium between cell loss and cell production in cell renewal systems as well as in the understanding of the radiation pathophysiology of mammalian organisms. The integrity of mammalian organisms with the need to maintain a constant ''millieu interior'' is depending on the normal functioning of cell renewal systems, especially those of epithelial surfaces and blood cell forming organs. All cell renewal systems of bodies have a very similar functional structure consisting of functional, proliferative - amplifying and stem cell compartments. They differ in transit and cell cycle times and in the number of amplification division - aside from the difference in their functional and biochemical make-up. The stem cell pools are providing the cells capable of differentiation without depleting their own kind. This can be achieved by symmetrical or assymmetrical stem cell division. In normal steady state, 50% of the stem cell division remain in the stem cell pool, while the other 50% leave it to differentiate, proliferate and mature, hemopoietic system is distributed throughout bodies. This is an important factor in the radiation biology of mammalian organisms since the loss of function in one area can be compensated for by more production in other areas, and locally depleted sites can be reseeded with the stem cells migrating in from blood. (Yamashita, S.)

  2. Radiation effects on the lymphocytic cell renewal system

    International Nuclear Information System (INIS)

    Most of the lymphocytes in mammals are concentrated in the thymus, lymph nodes, spleen, lymphatic formations (accumulation of lymphatic tissue), gastro-intestinal tract (including Peyer's glands), appendix, tonsils and adenoids. In animals on which comparative studies have been performed the thymus has proved to be the first organ in which lymphatic tissue appears. It has been demonstrated (Hammar, 1921) that there is a well-developed lymphocyte population in the thymus of the human embryo in the third month of pregnancy, well before lymphatic tissue appears in other organs. In the spleen for instance lymphopoiesis begins only when the embryo is six months old (Knoll, 1929) and the development of lymph nodes is delayed even more. According to Wischnewezkaja (1932) it begins during the first year after birth and continues until sexual maturity. In mice there is no lymphoid tissue in the embryo on the twelfth day of development; the thymus at that time consists only of epithelial and mesenchymal tissue. The lymphopoietic activity appears on the fourteenth day of pregnancy and the thymus gland becomes lymphoid on the sixteenth day. A number of authors have investigated the development of lymphoid tissue in rabbits and found that the thymus is the first organ in which lymphoid tissue develops; the spleen, the peripheral lymph nodes and the intestine occupy second place. Similar observations were made on dogs (Kelly, 1963). There is now a consensus of opinion that in most mammals the primary lymphoid organ is the thymus from which lymphoid cells disseminate into the mesenchymal tissues (spleen and lymph nodes) where they perform their immunological function. The effect of irradiation on this specific property of the lymphocytes is discussed in another chapter

  3. Renewable Energy Systems

    DEFF Research Database (Denmark)

    Lund, Henrik

    2014-01-01

    are to be found when the electricity sector is combined with the heating and cooling sectors and/or the transportation sector. Moreover, the combination of electricity and gas infrastructures may play an important role in the design of future renewable energy systems. The paper illustrates why electricity smart...

  4. Effects of prolonged moderate body deuteration on proliferative activity in major cell renewal systems in mice

    International Nuclear Information System (INIS)

    To evaluate the effects of prolonged moderate body deuteration on incorporation of tritiated thymidine (3HTdR) into the DNA of major cell renewal systems, young adult mice were given drinking fluid containing 30 % heavy water for 7, 14, 21, 42 and 70 days. Control mice drank tap water. Three hours prior to sacrifice, 925 kBq of HTdR were injected intravenously. Following extraction of the bulk of the soluble activity with an aqueous formalin solution, the residual 3H-activity of the organs was assayed by liquid scintillation counting and by autoradiography. The total thymic 3H-activity and the thymic weight, particularly of the cortex, were significantly reduced indeuterated mice early in the course of the experiment. The fraction of labeled thymocytes diminished to less than one half of the control values on day 70. The 3H-activity of the bone marrow in deuterated mice was reduced to about 3.4 of control values. In contrast, the total 3H-activity of the small intestine, as well as mean labeling index and mitotic index of small intestinal epithelia, were mot markedly altered in deuterated versus control mice. Drinking water containing 30 % of heavy water did thus not result in generalized, profound and progressive disturbance of HTdR incorporation in all the major cell renewal systems in the mouse. The thymus and, to a lesser extent, the bone marrow, were unquestionably affected, but the depression of HTdR incorporation did not increase markedly in the course of 10 weeks. In these terms, the toxicity of 30 % heavy wateer in the drinking fluid appears minor. This is of particular interest since exposure to similar concentrations is known to elicit immunodepressive and/or antineoplastic effects

  5. Renewable Energy Devices and Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ionel, Dan M.

    2015-01-01

    and commercial applications are provided. Fuel cells, solar thermal, wave generators, and energy storage systems are also briefly presented and illustrated. Challenges and future trends for 2025 are summarized in a table for on-shore and off-shore wind energy, solar power, including photovoltaic and......In this paper, essential statistics demonstrating the increasing role of renewable energy generation are firstly discussed. A state of the art review section covers fundamentals of wind turbines and PV systems. Included are schematic diagrams illustrating the main components and system topologies...... and the fundamental and increasing role of power electronics as an enabler for renewable energy integration, and for the future power system and smart grid. Recent examples of research and development, including new devices and system installations for utility power plants, as well for as residential...

  6. Design, Operation, Control, and Economics of a Photovoltaic/Fuel Cell/Battery Hybrid Renewable Energy System for Automotive Applications

    Directory of Open Access Journals (Sweden)

    Zachary S. Whiteman

    2015-06-01

    Full Text Available Meeting rapidly growing global energy demand—without producing greenhouse gases or further diminishing the availability of non-renewable resources—requires the development of affordable low-emission renewable energy systems. Here, we develop a hybrid renewable energy system (HRES for automotive applications—specifically, a roof-installed photovoltaic (PV array combined with a PEM fuel cell/NiCd battery bus currently operating shuttle routes on the University of Delaware campus. The system’s overall operating objectives—meeting the total power demand of the bus and maintaining the desired state of charge (SOC of the NiCd battery—are achieved with appropriately designed controllers: a logic-based “algebraic controller” and a standard PI controller. The design, implementation, and performance of the hybrid system are demonstrated via simulation of real shuttle runs under various operating conditions. The results show that both control strategies perform equally well in enabling the HRES to meet its objectives under typical operating conditions, and under sudden cloud cover conditions; however, at consistently high bus speeds, battery SOC maintenance is better, and the system consumes less hydrogen, with PI control. An economic analysis of the PV investment necessary to realize the HRES design objectives indicates a return on investment of approximately 30% (a slight, but nonetheless positive, ~$550 profit over the bus lifetime in Newark, DE, establishing the economic viability of the proposed addition of a PV array to the existing University of Delaware fuel cell/battery bus.

  7. Introduction to Renewable Energy Systems

    DEFF Research Database (Denmark)

    Ma, Ke; Yang, Yongheng; Blaabjerg, Frede

    2014-01-01

    view. It is concluded that as the quick development of renewable energy, wind power and PV power both show great potential to be largely integrated into the power grid. Power electronics is playing essential role in both of the systems to achieve more controllable, efficient, and reliable energy...

  8. Fuel Cells for Balancing Fluctuation Renewable Energy Sources

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad

    2007-01-01

    In the perspective of using fuel cells for integration of fluctuating renewable energy the SOFCs are the most promising. These cells have the advantage of significantly higher electricity efficiency than competing technologies and fuel flexibility. Fuel cells in general also have the advantage of......% of the electricity and with the best measures for improving flexibility have already been taken, making fuels via electrolysis is one of the alternatives to integrate more renewable energy. Creating the road map to a 100% renewable energy systems require difficult choices between balancing...

  9. Manipulating Midbrain Stem Cell Self-Renewal

    OpenAIRE

    Joseph J LoTurco; Kriegstein, Arnold R.

    2008-01-01

    In this issue of Cell Stem Cell, Falk and colleagues (Falk et al., 2008) demonstrate that differential responsiveness to TGF-b signaling selectively modulates self-renewal of dorsal midbrain stem cells. This observation may lead to strategies for expanding specific neural stem cell subtypes.

  10. Integrating renewables into energy systems

    International Nuclear Information System (INIS)

    An analysis of renewable energy schemes was undertaken via case studies in China, India, Indonesia, Kenya, South Africa, Thailand and Zimbabwe, that provided an insight into the application of best practice for overcoming market, technical and financial barriers to the establishment of the sustainable markets required for the large-scale deployment of renewable energy technologies. The project showed clearly the need to select and target interventions according to the context. Lessons were extracted against a number of themes, as well as against the various technologies analysed and simple guides to the principles of best practice were derived under the following headings:- experience of gaining access to (micro) finance; the technical and non-technical issues raised when small, typically independent, generators seek access to central electricity grid systems; how to best undertake awareness raising and dissemination activities; promoting, building and operating biogas systems; promoting, building and operating solar (photovoltaic) home systems; promoting, building and operating grid connected wind power; promoting, building and operating solar hot water systems; promoting agricultural cogeneration using crop residues. (author)

  11. Identification of a novel gene signature of ES cells self-renewal fluctuation through system-wide analysis.

    Directory of Open Access Journals (Sweden)

    Luigi Cerulo

    Full Text Available Embryonic Stem cells (ESCs can be differentiated into ectoderm, endoderm, and mesoderm derivatives, producing the majority of cell types. In regular culture conditions, ESCs' self-renewal is maintained through molecules that inhibit spontaneous differentiation enabling long-term cellular expansion. This undifferentiating condition is characterized by multiple metastable states that fluctuate between self-renewal and differentiation balance. Here, we aim to characterize the high-pluripotent ESC metastate marked by the expression of Zscan4 through a supervised machine learning framework based on an ensemble of support vector machine (SVM classifiers. Our study revealed a leukaemia inhibitor factor (Lif dependent not-canonical pluripotency signature (AF067063, BC061212, Dub1, Eif1a, Gm12794, Gm13871, Gm4340, Gm4850, Tcstv1/3, and Zfp352, that specifically marks Zscan4 ESCs' fluctuation. This novel ESC metastate is enhanced by high-pluripotency culture conditions obtained through Extracellular signal Regulated-Kinase (ERK and Glycogen synthase kinase-3 (Gsk-3 signaling inhibition (2i. Significantly, we reported that the conditional ablation of the novel ESC metastate marked by the expression of Gm12794 is required for ESCs self-renewal maintenance. In conclusion, we extend the comprehension of ESCs biology through the identification of a novel molecular signature associated to pluripotency programming.

  12. Renewable and efficient electric power systems

    CERN Document Server

    Masters, Gilbert M

    2013-01-01

    A solid, quantitative, practical introduction to a wide range of renewable energy systems-in a completely updated, new edition The second edition of Renewable and Efficient Electric Power Systems provides a solid, quantitative, practical introduction to a wide range of renewable energy systems. For each topic, essential theoretical background is introduced, practical engineering considerations associated with designing systems and predicting their performance are provided, and methods for evaluating the economics of these systems are presented. While the book focuses on

  13. A focus on parietal cells as a renewing cell population

    Institute of Scientific and Technical Information of China (English)

    Sherif; M; Karam

    2010-01-01

    The fact that the acidsecreting parietal cells undergo continuous renewal has been ignored by many gastroenterologists and cell biologists. In the past, it was thought that these cells were static. However, by using 3Hthymidine radioautography in combination with electron microscopy, it was possible to demonstrate that parietal cells belong to a continuously renewing epithelial cell lineage. In the gastric glands, stem cells anchored in the isthmus region are responsible for the production of parietal cells...

  14. Potential of renewable energy systems in China

    DEFF Research Database (Denmark)

    Liu, Wen; Lund, Henrik; Mathiesen, Brian Vad;

    2011-01-01

    this process, assessment of domestic renewable energy sources is the first step. Then appropriate methodologies are needed to perform energy system analyses involving the integration of more sustainable strategies. Denmark may serve as an example of how sustainable strategies can be implemented. The...... energy system. The conclusion is that China’s domestic renewable energy sources are abundant and show the possibility to cover future energy demand; the methodologies used to analyse a 100% renewable energy system are applicable in China. Therefore, proposing an analysis of a 100% renewable energy system...... inappropriate energy consumption structure should be changed. As an alternative, a suitable infrastructure for the implementation of renewable energy may serve as a long-term sustainable solution. The perspective of a 100% renewable energy system has been analyzed and discussed in some countries previously. In...

  15. Renewal Processes and Repairable Systems

    OpenAIRE

    Suyono

    2003-01-01

    In this thesis we discuss the following topics: 1. Renewal reward processes The marginal distributions of renewal reward processes and its version, which we call in this thesis instantaneous reward processes, are derived. Our approach is based on the theory of point processes, especially Poisson point processes. The idea is to represent the renewal reward processes and its version as functionals of Poisson point processes. Important tools we use are the Palm formula and the Laplace functional...

  16. Investigation of an integrated hydrogen production system based on nuclear and renewable energy sources: Comparative evaluation of hydrogen production options with a regenerative fuel cell system

    International Nuclear Information System (INIS)

    Hydrogen has risen as a sustainable and efficient energy carrier option in reducing environmental pollution, and is seen as a potential solution for the current energy crisis. Hydrogen production via water decomposition is a potential process for direct utilization of nuclear thermal energy to increase efficiency and thereby facilitate energy savings. While many of the available renewable energy resources are limited due to their reliability, quality, quantity and density, nuclear energy has the potential to contribute a significant share of energy supply with very limited impacts to climate change. The proposed model in this study is an integrated hydrogen production system combining both nuclear and solar energy sources. This integrated system includes storage of hydrogen and its conversion to electricity by a regenerative fuel cell system when needed. There are many matured water splitting processes that can be linked with the nuclear and solar energy sources to decompose water to its constituents, among which is hydrogen. In this regard, a comparative study is carried out to evaluate an optimal and feasible hydrogen production/storage process with a regenerative fuel cell that can be linked to this integrated system. Studies conducted here on hydrogen production processes show the thermochemical water decomposition to be the better option for producing hydrogen, comparing to electrolysis, due to its high efficiencies and low costs. Energy and exergy efficiencies of various hydrogen production processes, and fuel cell systems are evaluated and compared. Also, a parametric study is conducted on these efficiencies to see the effect of various operating conditions. - Highlights: • The proposed model is an integrated hydrogen production system combining both nuclear and solar energies. • Hydrogen production and storage technologies are reviewed comprehensively to determine the most appropriate option. • A comparative analysis is implemented on several hydrogen

  17. A focus on parietal cells as a renewing cell population

    Directory of Open Access Journals (Sweden)

    Sherif M Karam

    2010-02-01

    Full Text Available The fact that the acid-secreting parietal cells undergo continuous renewal has been ignored by many gastroenterologists and cell biologists. In the past, it was thought that these cells were static. However, by using 3H-thymidine radioautography in combination with electron microscopy, it was possible to demonstrate that parietal cells belong to a continuously renewing epithelial cell lineage. In the gastric glands, stem cells anchored in the isthmus region are responsible for the production of parietal cells. The stem cells give rise to three main progenitors: prepit, preneck and preparietal cells. Parietal cells develop either directly from the non-cycling preparietal cells or less commonly via differentiation of the cycling prepit and preneck cell progenitors. The formation of a parietal cell is a sequential process which involves diminishment of glycocalyx, production of cytoplasmic tubulovesicles, an increase in number and length of microvilli, an increase in number and size of mitochondria, and finally, expansion and invagination of the apical membrane with the formation of an intracellular canalicular system. Little is known about the genetic counterparts of these morphological events. However, the time dimension of parietal cell production and the consequences of its alteration on the biological features of the gastric gland are well documented. The production of a new parietal cell takes about 2 d. However, mature parietal cells have a long lifespan during which they migrate bi-directionally while their functional activity for acid secretion gradually diminishes. Following an average lifespan of about 54 d, in mice, old parietal cells undergo degeneration and elimination. Various approaches for genetic alteration of the development of parietal cells have provided evidence in support of their role as governors of the stem/progenitor cell proliferation and differentiation programs. Revealing the dynamic features and the various roles of

  18. The Palm Desert renewable [hydrogen] transportation system

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlin, C.E.; Lehman, P. [Humboldt State Univ., Arcata, CA (United States). Schatz Energy Research Center

    1998-08-01

    This paper describes the Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen Transportation System Project for the period June 1997 through May 1998. The project began in March 1996. The goal of the Palm Desert Project is to develop a clean and sustainable transportation system for a community. The project demonstrates the practical utility of hydrogen as a transportation fuel and the proton exchange membrane (PEM) fuel cell as a vehicle power system. The project includes designing and building 4 fuel cell powered vehicles, a solar hydrogen generating and refueling station, and a fuel cell vehicle diagnostic center. Over this last year, SERC has built a fuel cell powered neighborhood electric vehicle and delivered it to the City of Palm Desert. The design of the hydrogen refueling station is near completion and it is anticipated that construction will be complete in the fall of 1998. The vehicles are currently being refueled at a temporary refueling station. The diagnostic center is being designed and maintenance procedures as well as computer diagnostic programs for the fuel cell vehicles are being developed. City employees are driving the vehicles daily and monitoring data are being collected. The drivers are pleased with the performance of the vehicles.

  19. Haemopoietic cell renewal in radiation fields.

    Science.gov (United States)

    Fliedner, T M; Nothdurft, W; Tibken, B; Hofer, E; Weiss, M; Kindler, H

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a "turbulence region" for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a "blood stem cell bank" might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container. PMID:11539991

  20. Haemopoietic cell renewal in radiation fields

    Science.gov (United States)

    Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

  1. Availability of a Renewable, Checked System

    DEFF Research Database (Denmark)

    Platz, O.

    1976-01-01

    Recurrent expressions are given for point and interval unavailability of a renewable system subjected to periodic checking/repair. The expressions are generalizations of the basic relations in the theory of discrete renewal processes. The asymptotic limits for long times follow simply from a...

  2. The Palm Desert Renewable Hydrogen Transportation System

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, P. [Humboldt State Univ., Arcata, CA (United States)

    1996-10-01

    The present paper describes, for purposes of the Department of Energy (DoE) Hydrogen Program Review, Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen Transportation System Project for the period January through June 1996. This period represents the first six months of the three year project. The estimated cost over three years is $3.9M, $1.859M of which is funded by the DoE ($600 k for fiscal year 1996). The goal of the Palm Desert Project is to develop a clean and sustainable transportation system for a community. The project will demonstrate the practical utility of hydrogen as a transportation fuel and proton exchange membrane (PEM) fuel cells as vehicle power plants. This transportation system will be developed in the City of Palm Desert in southern California and will include a fleet of 8 fuel cell powered vehicles, solar and wind powered hydrogen generating facilities, a consumer-ready refueling station, and a service infrastructure. The system holds the promise of a clean environment and an energy supply that is predictable, domestic, safe, and abundant. During, the first part of 1996 SERC has nearly completed building a fuel cell powered personal utility vehicle, which features an upgraded safety and computer system; they have designed and built a test bench that is able to mimic golf cart loads and test fuel cell system auxiliary components; they have begun the design of the solar hydrogen generating station; they have worked with Sandia National Laboratory on an advanced metal hydride storage system; they have increased the power density of the SERC fuel cell by as much as 50%; and they have reached out to the rest of the world with a new fact sheet, world wide web pages, a press release, video footage for a television program. and instruction within the community.

  3. Extrinsic and intrinsic factors controlling spermatogonial stem cell self-renewal and differentiation

    OpenAIRE

    Xing-Xing Mei; Jian Wang; Ji Wu

    2015-01-01

    Spermatogonial stem cells (SSCs), the stem cells responsible for male fertility, are one of a small number of cells with the abilities of both self-renewal and generation of large numbers of haploid cells. Technology improvements, most importantly, transplantation assays and in vitro culture systems have greatly expanded our understanding of SSC self-renewal and differentiation. Many important molecules crucial for the balance between self-renewal and differentiation have been recently identi...

  4. Renewable Energy Powered Water Treatment Systems

    OpenAIRE

    Richards, Bryce S.; Schäfer, Andrea

    2009-01-01

    There are many motivations for choosing renewable energy technologies to provide the necessary energy to power water treatment systems for reuse and desalination. These range from the lack of an existing electricity grid, particularly in remote areas, to securing future energy and water supplies, to purely financial incentives. While many renewable energy technologies exist the two dominant ones used for powering desalination systems are PV modules and wind turbines. While wave...

  5. Power Converters and Control of Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Teodorescu, Remus; Chen, Zhe;

    2004-01-01

    The global electrical energy consumption is steadily rising and therefore a continuous demand to increase the power generation capacity. A significant percentage of the required capacity increase can be based on renewable energy sources. Wind turbine technology, as the most cost effective renewable...... energy conversion system, will play an important part in our future energy supply. But other sources like microturbines, photovoltaics and fuel cell systems may also be serious contributor to the power supply. Characteristically, power electronics will be an efficient and important interface to the grid...... for the renewables and this paper will first briefly discuss three different alternative/renewable energy sources. Next, various configurations of small and medium power conversion topologies are presented including their control (mainly for PV-systems). Finally wind turbine configuration and their...

  6. Renewable Electricity Generation via Solar-Powered Methanol Reforming: Hybrid Proton Exchange Membrane Fuel Cell Systems Based on Novel Non-Concentrating, Intermediate-Temperature Solar Collectors

    Science.gov (United States)

    Real, Daniel J.

    Tremendous research efforts have been conducted studying the capturing and conversion of solar energy. Solar thermal power systems offer a compelling opportunity for renewable energy utilization with high efficiencies and excellent cost-effectiveness. The goal of this work was to design a non-concentrating collector capable of reaching temperatures above 250 °C, use this collector to power methanol steam reforming, and operate a proton exchange membrane (PEM) fuel cell using the generated hydrogen. The study presents the construction and characterization of a non-concentrating, intermediate-temperature, fin-in-tube evacuated solar collector, made of copper and capable of reaching stagnation temperatures of 268.5 °C at 1000 W/m2 irradiance. The collector was used to power methanol steam reforming, including the initial heating and vaporization of liquid reactants and the final heating of the gaseous reactants. A preferential oxidation (PROX) catalyst was used to remove CO from simulated reformate gas, and this product gas was used to operate a PEM fuel cell. The results show 1) that the outlet temperature is not limited by heat transfer from the absorber coating to the heat transfer fluid, but by the amount of solar energy absorbed. This implicates a constant heat flux description of the heat transfer process and allows for the usage of materials with lower thermal conductivity than copper. 2) It is possible to operate a PEM fuel cell from reformate gas if a PROX catalyst is used to remove CO from the gas. 3) The performance of the fuel cell is only slightly decreased (~4%) by CO2 dilution present in the reformate and PROX gas. These results provide a foundation for the first renewable electricity generation via solar-powered methanol reforming through a hybrid PEM fuel cell system based on novel non-concentrating, intermediate-temperature solar collectors.

  7. Implementation of Renewable Energy Systems in Denmark

    DEFF Research Database (Denmark)

    Meyer, Niels I

    1997-01-01

    Denmark has been one of the first countries in the world to commit itself to a sustainable energy development. This has been substantiated by two official action plans from 1990 and 1996 with emphasis on energy efficiency and supply systems based on renewable energy. In year 2005, renewable energ...... sources are planned to cover 12-14% and in year 2030 about 35% of total Danish energy demand. This paper reviews the experiences with implementation of renewable energy in Denmark with a focus on wind power and biomass....

  8. Power Electronics for Renewable Energy Systems

    DEFF Research Database (Denmark)

    Choi, U. M.; Lee, K. B.; Blaabjerg, Frede

    2012-01-01

    The use of renewable energy sources are increased because of the depletion of natural resources and the increasing pollution level from energy production. The wind energy and the solar energy are most widely used among the renewable energy sources. Power electronics is needed in almost all kinds...... of renewable energy system. It controls the renewable source and interfaces with the load effectively, which can be grid-connected or van work in stand-alone mode. In this presentation, overview of wind and photovoltaic energy systems are introduced. Next, the power electronic circuits behind the most common...... wind and photovoltaic configurations are discussed. Finally, their controls and important requirements for grid connection are explained....

  9. Epigenetics in Intestinal Epithelial Cell Renewal.

    Science.gov (United States)

    Roostaee, Alireza; Benoit, Yannick D; Boudjadi, Salah; Beaulieu, Jean-François

    2016-11-01

    A controlled balance between cell proliferation and differentiation is essential to maintain normal intestinal tissue renewal and physiology. Such regulation is powered by several intracellular pathways that are translated into the establishment of specific transcription programs, which influence intestinal cell fate along the crypt-villus axis. One important check-point in this process occurs in the transit amplifying zone of the intestinal crypts where different signaling pathways and transcription factors cooperate to manage cellular proliferation and differentiation, before secretory or absorptive cell lineage terminal differentiation. However, the importance of epigenetic modifications such as histone methylation and acetylation in the regulation of these processes is still incompletely understood. There have been recent advances in identifying the impact of histone modifications and chromatin remodelers on the proliferation and differentiation of normal intestinal crypt cells. In this review we discuss recent discoveries on the role of the cellular epigenome in intestinal cell fate, development, and tissue renewal. J. Cell. Physiol. 231: 2361-2367, 2016. © 2016 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. PMID:27061836

  10. Career Directions--Renewable Energy Systems Integrator

    Science.gov (United States)

    Fleeman, Stephen R.

    2012-01-01

    Renewable energy systems are beginning to appear everywhere. Solar modules are creating "blue roofs" that convert the energy from the sun into household electricity. Solar thermal systems on roofs can generate hot water. Wind turbines catch breezes to provide even more electricity. Recommendations for saving energy, specifying systems for…

  11. Power electronics for renewable and distributed energy systems a sourcebook of topologies, control and integration

    CERN Document Server

    Chakraborty, Sudipta; Kramer, William E

    2013-01-01

    While most books approach power electronics and renewable energy as two separate subjects, Power Electronics for Renewable and Distributed Energy Systems takes an integrative approach; discussing power electronic converters topologies, controls and integration that are specific to the renewable and distributed energy system applications. An overview of power electronic technologies is followed by the introduction of various renewable and distributed energy resources that includes photovoltaics, wind, small hydroelectric, fuel cells, microturbines and variable speed generation. Energy storage s

  12. Modeling of hybrid renewable energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, M.K. [Birla Institute of Technology and Science, Pilani - Goa Campus, Zuari Nagar, Goa 403 726 (India); Deshmukh, S.S. [Centre for Renewable Energy and Environment Development (CREED), Mechanical Engineering Group, Birla Institute of Technology and Science (BITS), Pilani Campus, Pilani 333 031 (India)

    2008-01-15

    Hybrid renewable energy systems (HRES) are becoming popular for remote area power generation applications due to advances in renewable energy technologies and subsequent rise in prices of petroleum products. Economic aspects of these technologies are sufficiently promising to include them in developing power generation capacity for developing countries. Research and development efforts in solar, wind, and other renewable energy technologies are required to continue for, improving their performance, establishing techniques for accurately predicting their output and reliably integrating them with other conventional generating sources. The paper describes methodologies to model HRES components, HRES designs and their evaluation. The trends in HRES design show that the hybrid PV/wind energy systems are becoming gaining popular. The issues related to penetration of these energy systems in the present distribution network are highlighted. (author)

  13. Tunisia Renewable Energy Project systems description report

    Science.gov (United States)

    Scudder, L. R.; Martz, J. E.; Ratajczak, A. F.

    1986-01-01

    In 1979, the Agency for International Development (AID) initiated a renewable energy project with the Government of Tunisia to develop an institutional capability to plan and institute renewable energy technologies in a rural area. The specific objective of the district energy applications subproject was to demonstrate solar and wind energy systems in a rural village setting. The NASA Lewis Research Center was asked by the AID Near East Bureau to manage and implement this subproject. This report describes the project and gives detailed desciptions of the various systems.

  14. Integrated transport and renewable energy systems

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Nørgaard, Per

    2007-01-01

    Governments worldwide aim at reducing CO2 emissions and expanding renewable energy. A key element in achieving such a goal is to use renewable energy in transport such as biofuels. However, efforts to promote single transport technologies and single fuels only represent a partial solution. No...... transport. It is concluded that a 100 per cent renewable energy transport system is possible but is connected to significant challenges in the path towards it. Biomass is a limited resource and it is important to avoid effecting the production. The integration of the transport with the remaining energy...... single technology can solve the problem of ever increasing CO2 emissions from transport. Transport must be integrated into energy planning, as electricity and heating. In this paper, a coherent effort to integrate transport into energy planning is proposed, using multiple means promoting sustainable...

  15. Micro-financing of renewable energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Bunse, Maike; Wallbaum, Holger [triple innova (Germany); Dienst, Carmen [Wuppertal Inst. for Climate, Environment, Energy (Germany)

    2007-07-01

    While improved energy services have many quality of life benefits like lighting or television, the productive use of electricity can also help to reduce poverty, leading to increased profitability and productivity for micro, small and medium enterprises, and small industries. The remoteness of rural locations usually makes it difficult to expand electricity supply through a centralised grid system. Therefore people living in off-grid regions often rely on expensive fossil fuels like diesel and kerosene. People in remote areas often do not have the financial background to afford the initial costs for renewable energy applications. Micro-financing of renewable energy systems is a possible answer to provide financial services and support productive activities in a sustainable manner for low-income people. There are various types of microfinance institutions (MFIs), ranging from local cooperatives, NGOs, credit unions, private commercial banks and non-bank financial institutions as well as parts of state-owned banks.To underline the benefits of micro financing renewable energy systems, good practice projects of local microfinance activities are presented. These projects have been identified in the course of WISIONS, an initiative of the Wuppertal Inst. for Climate, Environment and Energy with support of ProEvolution, a Swiss-based foundation. The two different approaches of the project support on one side the realisation of new project ideas (SEPS - Sustainable Energy Project Support) and on the other spread successful examples (PREP - Promotion of Resource Efficiency Projects). Through the PREP field of action, good practices in energy and resource efficiency are spread worldwide through the Internet and brochures. In the 5th PREP-brochure of WISIONS on 'Microfinance and Renewable Energy' five good-practice examples are shown that link this promising financing system with modern and sustainable renewable energy technologies.

  16. Renewable Energy Laboratory for Lighting Systems

    OpenAIRE

    Cristian, Dumitru; Adrian, Gligor

    2010-01-01

    Nowadays, the electric lighting is an important part of our lives and also represents a significant part of the electric power consumption. Alternative solutions such as renewable energy applied in this domain are thus welcomed. This paper presents a workstation conceived for the study of photovoltaic solar energy for lighting systems by students of power engineering and civil engineering faculty. The proposed system is realized to study the generated photovoltaic solar energy parameters for ...

  17. Optimised Hybrid Integrated Renewable Energy System

    Directory of Open Access Journals (Sweden)

    Dr. Arun Sandilya

    2012-10-01

    Full Text Available A hybrid integrated renewable energy system for an isolated small community, where grid extension is considered uneconomical. This paper proposed cost optimization through dynamic matching between load and proper equipment sizing. The Matlab based computer program developed for determining the most cost effective energy source to supply required load any given time of the day. Integrated system based on green energy utilization and rural electricity development.

  18. Energy Systems With Renewable Hydrogen Compared to Direct Use of Renewable Energy in Austria

    International Nuclear Information System (INIS)

    The current Austrian energy system has a renewable energy share of 20% - 11% hydropower and 9 % biomass - of total primary energy consumption. Whereas a possible future introduction of renewable hydrogen must be seen in the context of current energy policies in Austria e.g. increase of energy efficiency and use of renewable energy, reduction of greenhouse gas emissions. The aim of the research project is a life cycle based comparison of energy systems with renewable hydrogen from hydropower, wind, photovoltaic and biomass compared to the direct use of renewable energy for combined heat and power applications and transportation services. In particular this paper focuses on the main question, if renewable energy should be used directly or indirectly via renewable hydrogen. The assessment is based on a life cycle approach to analyse the energy efficiency, the material demand, the greenhouse gas emissions and economic aspects e.g. energy costs and some qualitative aspects e.g. energy service. The overall comparison of the considered energy systems for transportation service and combined heat and electricity application shows, that renewable hydrogen might be beneficial mainly for transportation services, if the electric vehicle will not be further developed to a feasibly wide-spread application for transportation service in future. For combined heat and electricity production there is no advantage of renewable hydrogen versus the direct use of renewable energy. Conclusions for Austria are therefore: 1) renewable hydrogen is an interesting energy carrier and might play an important role in a future sustainable Austrian energy system; 2) renewable hydrogen applications look most promising in the transportation sector; 3) renewable hydrogen applications will be of low importance for combined heat and electricity applications, as existing technologies for direct use of renewable energy for heat and electricity are well developed and very efficient; 4) In a future '100

  19. Communication Systems for Grid Integration of Renewable Energy Resources

    CERN Document Server

    Yu, F Richard; Xiao, Weidong; Choudhury, Paul

    2011-01-01

    There is growing interest in renewable energy around the world. Since most renewable sources are intermittent in nature, it is a challenging task to integrate renewable energy resources into the power grid infrastructure. In this grid integration, communication systems are crucial technologies, which enable the accommodation of distributed renewable energy generation and play extremely important role in monitoring, operating, and protecting both renewable energy generators and power systems. In this paper, we review some communication technologies available for grid integration of renewable energy resources. Then, we present the communication systems used in a real renewable energy project, Bear Mountain Wind Farm (BMW) in British Columbia, Canada. In addition, we present the communication systems used in Photovoltaic Power Systems (PPS). Finally, we outline some research challenges and possible solutions about the communication systems for grid integration of renewable energy resources.

  20. Policies for 100% Renewable Energy Systems

    DEFF Research Database (Denmark)

    Hvelplund, Frede

    2014-01-01

    fluctuating, abundant and clean energy sources. “Stored” fossil fuels can be used when needed; fluctuating energy sources must be captured when available and transformed to meet the energy needs of society in the right amounts and at the right time. We are amidst this change. Renewable energy has come of age......The official Danish energy policy goal is both to increase the wind power share of electricity consumption from 33% in 2014 to 50% by 2020 and to have a 100% renewable energy based energy system by 2050. This is a huge technological change from stored, scarce and polluting fossil fuels to...... and is no longer a minor technology experimenting in the corner of the energy scene, but has become a large new technology taking away considerable market shares from the old fossil fuel technologies....

  1. Intermittent Stem Cell Cycling Balances Self-Renewal and Senescence of the C. elegans Germ Line

    OpenAIRE

    Cinquin, A.; Chiang, M.; Paz, A.; Hallman, S; Yuan, O; Vysniauskaite, I; Fowlkes, CC; Cinquin, O.

    2016-01-01

    Self-renewing organs often experience a decline in function in the course of aging. It is unclear whether chronological age or external factors control this decline, or whether it is driven by stem cell self-renewal-for example, because cycling cells exhaust their replicative capacity and become senescent. Here we assay the relationship between stem cell cycling and senescence in the Caenorhabditis elegans reproductive system, defining this senescence as the progressive decline in "reproducti...

  2. Integrated transport and renewable energy systems

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Nørgaard, P.

    2008-01-01

    No single technology can solve the problem of ever increasing CO2 emissions from transport. Here, a coherent effort to integrate transport into energyplanning is proposed, using multiple means promoting sustainable transport. It is concluded that a 100 per cent renewable energy transport system is...... possible but is connected to significant challenges in the path towards it. Biomass is a limited resource and it is important to avoid effecting the production of food. The integration of the transport with the energy system is crucial as is a multi-pronged strategy. Short term solutions have to consider...

  3. Hydrogen, fuel cells and renewable energy integration in islands

    Energy Technology Data Exchange (ETDEWEB)

    Bauen, A.; Hart, D. [E4tech Ltd., Lausanne (Switzerland)]|[Imperial College Centre for Energy Policy and Technology, (United Kingdom); Foradini, F.; Hart, D. [E4tech Ltd., Lausanne (Switzerland)

    2002-07-01

    Remote areas such as islands rely on costly and highly polluting diesel and heavy fuel oil for their electricity supply. This paper explored the opportunities for exploiting economically and environmentally viable renewable energy sources, in particular hydrogen storage, on such islands. In particular, this study focused on addressing the challenge of matching energy supply with demand and with technical issues regarding weak grids that are hindered with high steady state voltage levels and voltage fluctuations. The main technical characteristics of integrated renewable energy and hydrogen systems were determined by modelling a case study for the island of El Hierro (Canary Islands). The paper referred to the challenges regarding the technical and economic viability of such systems and their contribution to the economic development of remote communities. It was noted that energy storage plays an important role in addressing supply and demand issues by offering a way to control voltage and using surplus electricity at times of low load. Electrical energy can be stored in the form of potential or chemical energy. New decentralized generation technologies have also played a role in improving the energy efficiency of renewable energy sources. The feasibility of using hydrogen for energy storage was examined with particular reference to fuel-cell based energy supply in isolated island communities. 4 refs., 5 figs.

  4. Hydrogen, fuel cells and renewable energy integration in islands

    International Nuclear Information System (INIS)

    Remote areas such as islands rely on costly and highly polluting diesel and heavy fuel oil for their electricity supply. This paper explored the opportunities for exploiting economically and environmentally viable renewable energy sources, in particular hydrogen storage, on such islands. In particular, this study focused on addressing the challenge of matching energy supply with demand and with technical issues regarding weak grids that are hindered with high steady state voltage levels and voltage fluctuations. The main technical characteristics of integrated renewable energy and hydrogen systems were determined by modelling a case study for the island of El Hierro (Canary Islands). The paper referred to the challenges regarding the technical and economic viability of such systems and their contribution to the economic development of remote communities. It was noted that energy storage plays an important role in addressing supply and demand issues by offering a way to control voltage and using surplus electricity at times of low load. Electrical energy can be stored in the form of potential or chemical energy. New decentralized generation technologies have also played a role in improving the energy efficiency of renewable energy sources. The feasibility of using hydrogen for energy storage was examined with particular reference to fuel-cell based energy supply in isolated island communities. 4 refs., 5 figs

  5. Epigenetic modifications and self-renewal regulation of mouse germline stem cells

    Institute of Scientific and Technical Information of China (English)

    Jiyoung Lee; Takashi Shinohara

    2011-01-01

    Germline stem (GS) cells were established from gonocytes and spermatogonia of postnatal mouse testes. GS cells proliferate in the presence of several kinds of cytokines, and a small percentage of GS cells also show spermatogonial stem cell (SSC) activity, i.e., they differentiate into sperm after being transplanted into infertile mouse testes without endogenous spermatogenesis. Interestingly, in GS cell culture, we also found that pluripotent stem cells (multipotent germline stem cells (mGS cells)) could be derived and these mGS cells do not have normal androgenetic genomic imprinting marks that are shown in GS cells, e.g., H19 hypermethylation. A new culture system for fetal male germ cells (embryonic GS (eGS) cells) has also been recently developed. Although these cells exhibited SSC potential, the offspring from cultured cells showed heritable imprinting defects in their DNA methylation patterns. In an attempt to understand the self-renewal machinery in SSCs, we transfected H-Ras and cylin D2 into GS cells, and successfully reconstructed the SSC self-renewal ability without using exogenous cytokines. Although these cells showed SSC activity in germ cell transplantation assays, we also found development of seminomatous tumors, possibly induced by excessive self-renewing signal. These stem cell culture systems are useful tools not only for understanding the mechanisms of self-renewal or epigenetic reprogramming but also for clarifying the mechanism of germ cell tumor development.

  6. Energy System Analysis of 100 Per cent Renewable Energy Systems

    DEFF Research Database (Denmark)

    Lund, Henrik; Mathiesen, Brian Vad

    2007-01-01

    This paper presents the methodology and results of the overall energy system analysis of a 100 per cent renewable energy system. The input for the systems is the result of a project of the Danish Association of Engineers, in which 1600 participants during more than 40 seminars discussed and desig......This paper presents the methodology and results of the overall energy system analysis of a 100 per cent renewable energy system. The input for the systems is the result of a project of the Danish Association of Engineers, in which 1600 participants during more than 40 seminars discussed...... the electricity supply and demand and to exchange electricity productions on the international electricity markets. The results are detailed system designs and energy balances for two energy target years: year 2050 with 100 per cent renewable energy from biomass and combinations of wind, wave and solar power...

  7. The RenewElec Project: Variable Renewable Energy and the Power System

    Energy Technology Data Exchange (ETDEWEB)

    Apt, Jay

    2014-02-14

    Variable energy resources, such as wind power, now produce about 4% of U.S. electricity. They can play a significantly expanded role if the U.S. adopts a systems approach that considers affordability, security and reliability. Reaching a 20-30% renewable portfolio standard goal is possible, but not without changes in the management and regulation of the power system, including accurately assessing and preparing for the operational effects of renewable generation. The RenewElec project will help the nation make the transition to the use of significant amounts of electric generation from variable and intermittent sources of renewable power.

  8. Smart power systems and renewable energy system integration

    CERN Document Server

    2016-01-01

    This monograph presents a wider spectrum of researches, developments, and case specific studies in the area of smart power systems and integration of renewable energy systems. The book will be for the benefit of a wider audience including researchers, postgraduate students, practicing engineers, academics, and regulatory policy makers. It covers a wide range of topics from fundamentals, and modelling and simulation aspects of traditional and smart power systems to grid integration of renewables; Micro Grids; challenges in planning and operation of a smart power system; risks, security, and stability in smart operation of a power system; and applied research in energy storage. .

  9. The Ganil computer control system renewal

    International Nuclear Information System (INIS)

    Since 1982 the GANIL heavy ion accelerator has been under the control of 16-bit minicomputers MITRA, programmable logic controllers and microprocessorized Camac controllers, structured into a partially centralized system. This control system has to be renewed to meet the increasing demands of the accelerator operation which aims to provide higher quality ion beams under more reliable conditions. This paper gives a brief description of the existing control system and then discusses the main issues of the design and the implementation of the future control system: distributed powerful processors federated through Ethernet and flexible network-wide database access, VME standard and front-end microprocessors, enhanced color graphic tools and workstation based operator interface

  10. Future UK markets for stand-alone renewable energy systems

    International Nuclear Information System (INIS)

    A study to identify and quantify the market for stand-alone renewable energy supplies of power (photovoltaics, wind and micro-hydro electricity systems) was described. The study focused on small systems, generally less than a few kW installed capacity. It was suggested that in the UK, the emphasis on grid-connected renewable energy technologies (RETs) has blurred the fact that it is 'off-grid' renewable systems that can offer more immediate real commercial markets for the renewables business. With the likelihood of a significant increase in demand for renewables world wide over the next ten years, the UK needs to make a special effort to become involved

  11. Renewable energy certification system-RECS project

    International Nuclear Information System (INIS)

    Electric power from renewable energy sources is generally not economically competitive. Environmental protection, in energy supply, safety and independence have introduced financial incentives in electric power generation from renewable energy sources

  12. Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

    OpenAIRE

    Nielsen, L.H.; Jørgensen K., null

    2000-01-01

    The aim of the project is to analyse energy, environmental and economic aspects of integrating electric vehicles in the future Danish energy system. Consequences of large-scale utilisation of electric vehicles are analysed. The aim is furthermore toillustrate the potential synergistic interplay between the utilisation of electric vehicles and large-scale utilisation of fluctuating renewable energy resources, such as wind power. Economic aspects for electric vehicles interacting with a liberal...

  13. Myostatin negatively regulates satellite cell activation and self-renewal

    OpenAIRE

    McCroskery, Seumas; Thomas, Mark; Maxwell, Linda; Sharma, Mridula; Kambadur, Ravi

    2003-01-01

    Satellite cells are quiescent muscle stem cells that promote postnatal muscle growth and repair. Here we show that myostatin, a TGF-β member, signals satellite cell quiescence and also negatively regulates satellite cell self-renewal. BrdU labeling in vivo revealed that, among the Myostatin-deficient satellite cells, higher numbers of satellite cells are activated as compared with wild type. In contrast, addition of Myostatin to myofiber explant cultures inhibits satellite cell activation. Ce...

  14. Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

    International Nuclear Information System (INIS)

    The aim of the project is to analyse energy, environmental and economic aspects of integrating electric vehicles in the future Danish energy system. Consequences of large-scale utilisation of electric vehicles are analysed. The aim is furthermore to illustrate the potential synergistic interplay between the utilisation of electric vehicles and large-scale utilisation of fluctuating renewable energy resources, such as wind power. Economic aspects for electric vehicles interacting with a liberalised electricity market are analysed. The project focuses on battery electric vehicles and fuel cell vehicles based on hydrogen. Based on assumptions on the future technical development for battery electric vehicles, fuel cell vehicles on hydrogen, and for the conventional internal combustion engine vehicles, scenarios are set up to reflect expected options for the long-term development of road transport vehicles. Focus is put on the Danish fleet of passenger cars and delivery vans. The scenario analysis includes assumptions on market potential developments and market penetration for the alternative vehicles. Vehicle replacement rates in the Danish transport fleet and the size of fleet development are based on data from The Danish Road Directorate. The electricity supply system development assumed is based on the Danish energy plan, Energy 21, The Plan scenario. The time horizon of the analysis is year 2030. Results from the scenario analysis include the time scales involved for the potential transition towards electricity based vehicles, the fleet composition development, the associated developments in transport fuel consumption and fuel substitution, and the potential CO2-emission reduction achievable in the overall transport and power supply system. Detailed model simulations, on an hourly basis, have furthermore been carried out for year 2005 that address potential electricity purchase options for electric vehicles in the context of a liberalised electricity market. The

  15. The system architecture for renewable synthetic fuels

    DEFF Research Database (Denmark)

    Ridjan, Iva

    To overcome and eventually eliminate the existing heavy fossil fuels in the transport sector, there is a need for new renewable fuels. This transition could lead to large capital costs for implementing the new solutions and a long time frame for establishing the new infrastructure unless a suitable...... infrastructure is present. The system integration of synthetic fuels will therefore depend on the existing infrastructure and the possibility of continuing its exploitation to minimize the costs and maximize the use of the current infrastructure in place. The production process includes different steps and...... production plants, so it is important to implement it in the best manner possible to ensure an efficient and flexible system. The poster will provide an overview of the steps involved in the production of synthetic fuel and possible solutions for the system architecture based on the current literature and...

  16. Power electronics for renewable energy systems

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede

    2009-01-01

    The global electrical energy consumption is still rising and there is a demand to double the power capacity within 20 years. The production, distribution and use of energy should be as technological efficient as possible and incentives to save energy at the end-user should also be set up. Deregul......, wind energy and photovoltaics, which by means of power electronics are changing from being minor energy sources to be acting as important power sources in the energy system........ Deregulation of energy has in the past lowered the investment in larger power plants, which means the need for new electrical power sources may be very high in the near future. Two major technologies will play important roles to solve the future problems. One is to change the electrical power production...... sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources...

  17. Renewable Energy Options for a Utility System

    Science.gov (United States)

    Ahmadi, Lena; Panjeshahi, M. Hassan; Perry, Simon

    2009-05-01

    In this paper, renewable energies have been re-addressed with respect to the potentials and feasibility of being incorporated in process industries. Within a process, utility system is considered to be the most appropriate place for using sustainable energies. For integrating the renewable energies, the pinch analysis is applied as the main tool to provide opportunity for energy conservation. The results demonstrated that the power generation by the wind is the most cost effective and environmentally friendly option for energy conservation in comparison to the other sustainable resources. However the tidal energy stands the least due to the long payback period. Also, a computer program has been developed, using MATLAB 7.3, to screen out different scenarios and perform economic study. The outcome data showed that, there are several different opportunities for the integration of alternative energies. Finally, this method has been applied to a case study and various retrofit projects have been identified, each of which has certain amount of CO2 reduction and estimated values for the required investment, saving potential and payback period.

  18. Muscle Satellite Cell Heterogeneity and Self-Renewal

    Directory of Open Access Journals (Sweden)

    Norio eMotohashi

    2014-01-01

    Full Text Available Adult skeletal muscle possesses extraordinary regeneration capacities. After muscle injury or exercise, large numbers of newly formed muscle fibers are generated within a week as a result of expansion and differentiation of a self-renewing pool of muscle stem cells termed muscle satellite cells. Normally, satellite cells are mitotically quiescent and reside beneath the basal lamina of muscle fibers. Upon regeneration, satellite cells are activated, and give rise to daughter myogenic precursor cells. After several rounds of proliferation, these myogenic precursor cells contribute to the formation of new muscle fibers. During cell division, a minor population of myogenic precursor cells returns to quiescent satellite cells as a self-renewal process. Currently, accumulating evidence has revealed the essential roles of satellite cells in muscle regeneration and the regulatory mechanisms, while it still remains to be elucidated how satellite cell self-renewal is molecularly regulated and how satellite cells are important in aging and diseased muscle. The number of satellite cells is decreased due to the changing niche during ageing, resulting in attenuation of muscle regeneration capacity. Additionally, in Duchenne muscular dystrophy (DMD patients, the loss of satellite cell regenerative capacity and decreased satellite cell number due to continuous needs for satellite cells lead to progressive muscle weakness with chronic degeneration. Thus, it is necessary to replenish muscle satellite cells continuously. This review outlines recent findings regarding satellite cell heterogeneity, asymmetric division and molecular mechanisms in satellite cell self-renewal which is crucial for maintenance of satellite cells as a muscle stem cell pool throughout life. In addition, we discuss roles in the stem cell niche for satellite cell maintenance, as well as related cell therapies for approaching treatment of DMD.

  19. Stem cells, self-renewal, and differentiation in the intestinal epithelium.

    NARCIS (Netherlands)

    van der Flier, L.G.; Clevers, H.

    2009-01-01

    The mammalian intestine is covered by a single layer of epithelial cells that is renewed every 4-5 days. This high cell turnover makes it a very attractive and comprehensive adult organ system for the study of cell proliferation and differentiation. The intestine is composed of proliferative crypts,

  20. Solid Oxide Fuel Cells Operating on Alternative and Renewable Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoxing; Quan, Wenying; Xiao, Jing; Peduzzi, Emanuela; Fujii, Mamoru; Sun, Funxia; Shalaby, Cigdem; Li, Yan; Xie, Chao; Ma, Xiaoliang; Johnson, David; Lee, Jeong; Fedkin, Mark; LaBarbera, Mark; Das, Debanjan; Thompson, David; Lvov, Serguei; Song, Chunshan

    2014-09-30

    This DOE project at the Pennsylvania State University (Penn State) initially involved Siemens Energy, Inc. to (1) develop new fuel processing approaches for using selected alternative and renewable fuels – anaerobic digester gas (ADG) and commercial diesel fuel (with 15 ppm sulfur) – in solid oxide fuel cell (SOFC) power generation systems; and (2) conduct integrated fuel processor – SOFC system tests to evaluate the performance of the fuel processors and overall systems. Siemens Energy Inc. was to provide SOFC system to Penn State for testing. The Siemens work was carried out at Siemens Energy Inc. in Pittsburgh, PA. The unexpected restructuring in Siemens organization, however, led to the elimination of the Siemens Stationary Fuel Cell Division within the company. Unfortunately, this led to the Siemens subcontract with Penn State ending on September 23rd, 2010. SOFC system was never delivered to Penn State. With the assistance of NETL project manager, the Penn State team has since developed a collaborative research with Delphi as the new subcontractor and this work involved the testing of a stack of planar solid oxide fuel cells from Delphi.

  1. Fuel Cells for Balancing Fluctuation Renewable Energy Sources

    OpenAIRE

    Mathiesen, Brian Vad

    2007-01-01

    In the perspective of using fuel cells for integration of fluctuating renewable energy the SOFCs are the most promising. These cells have the advantage of significantly higher electricity efficiency than competing technologies and fuel flexibility. Fuel cells in general also have the advantage of fast regulation abilities combined with excellent part-load efficiencies. Additionally scaling the cells from W to kW to MW is possible and does not influence the efficiencies of the cells. The feasi...

  2. Optimal design of hybrid renewable energy systems in buildings with low to high renewable energy ratio

    OpenAIRE

    Sharafi, M.; Elmekkawy, T.Y.; Bibeau, E.L.

    2015-01-01

    We develop a simulation-based meta-heuristic approach that determines the optimal size of a hybrid renewable energy system for residential buildings. This multi-objective optimization problem requires the advancement of a dynamic multi-objective particle swarm optimization algorithm that maximizes the renewable energy ratio of buildings and minimizes total net present cost and CO2 emission for required system changes. Three proven performance metrics evaluate the quality of the Pareto front g...

  3. Renewable energy operation and conversion schemes: a summary of discussions during the Seminar on Renewable Energy Systems

    OpenAIRE

    Zacharias, Peter; Teodorescu, Remus; Rodríguez Cortés, Pedro; Liserre, M.; Knapp, Wilfried; Spagnuolo, Giovanni; Petrone, Giovanni; Vasconcelos, Samuel; Carlo Cecati, Araújo; Friis-Madsen, Erik; Gubía, Eugenio; Hissel, Daniel; Jasinski, Marek

    2010-01-01

    A short summary of some speeches given during Seminar on Renewable Energy system (SERENE) is presented. The contributions have been mainly focused on power electronics for photovoltaic (PV) and sea wave energies, pointing out some aspects related to efficiency, reliability, and grid integration. Finally, main issues concerning fuel cell (FC) systems as generators based on hydrogen as a low environmental impact energy vector are presented.

  4. Renewable energy systems the choice and modeling of 100% renewable solutions

    CERN Document Server

    Lund, Henrik

    2009-01-01

    How can society quickly convert to renewable energy? Can worldwide energy needs ever be met through 100% renewable sources? The answers to these questions rest largely on the perception of choice in the energy arena. It is of pivotal importance that engineers, researchers and policymakers understand what choices are available, and reasonable, when considering the design and deployment of new energy systems. The mission of this new book, written by one of the world's foremost experts in renewable power, is to arm these professionals with the tools and methodologies necessary to make smart choic

  5. Polycomb Cbx family members mediate the balance between haematopoietic stem cell self-renewal and differentiation

    DEFF Research Database (Denmark)

    Klauke, Karin; Radulović, Višnja; Broekhuis, Mathilde;

    2013-01-01

    The balance between self-renewal and differentiation of adult stem cells is essential for tissue homeostasis. Here we show that in the haematopoietic system this process is governed by polycomb chromobox (Cbx) proteins. Cbx7 is specifically expressed in haematopoietic stem cells (HSCs), and its...

  6. Internet Renewable energy Information System (IRIS)

    DEFF Research Database (Denmark)

    Bäurle, Britta; Nielsen, Vilhjalmur; Ménard, Lionel

    1999-01-01

    Even though the Internet is now a widely accessible data source, the unorganised flood of information makes a specific request e.g. for renewable energy products inefficient. In addition, existing databases on renewable energies are often old and incomplete. The objective of IRIS has been...... to organise and retrieve renewable energy product information on the Internet instead of collecting it manually. Updating coincides with the self interestself-interest of manufacturers to present their latest renewable energy products on their own HTML documents. IRIS is based on a set of powerful tools...... and intends to find, extract, collect and index HTML documents with standardised META tags that are widely spread across web servers on the Internet. This paper presents the structure of IRIS, the software tools, and gives one example of how to categorise and prepare web-sites with product information...

  7. Development of a Prototype Renewable Energy System and its Modification to Suit Middle East Applications

    OpenAIRE

    Salman K Salman

    2011-01-01

    This paper concerns with exploitation of renewable energy sources for meeting energy requirements of remote locations. It presents an investigation which is based on a practical project that was executed in collaboration between academia and industry. It involves design and installation of a prototype integrated renewable energy system which consists of two 15 kW wind turbines, electrolyser, fuel cell system (FCS) and the associated control equipment. It was installed at ...

  8. Renewable energies - Fuel cell and hydrogen

    International Nuclear Information System (INIS)

    In July 2003 the Fuel Cell Program was established at IPEN in order to contribute to the national development in this area. The program was structured in a cross-cutting way involving human and infrastructure resources from IPEN Technical Departments. Three main areas were developed: PEMFC (Proton Exchange Membrane Fuel Cell): SOFC (Solid Oxide Fuel Cell); and REFORM (H2 production from ethanol reforming)

  9. Renewable energy systems in Mexico: Installation of a hybrid system

    Science.gov (United States)

    Pate, Ronald C.

    1993-05-01

    Sandia has been providing technical leadership on behalf of DOE and CORECT on a working level cooperative program with Mexico on renewable energy (PROCER). As part of this effort, the Sandia Design Assistance Center (DAC) and the solar energy program staff at Instituto de Investigaciones Electricas (IIE) in Cuernavaca, Mexico, recently reached agreement on a framework for mutually beneficial technical collaboration on the monitoring and field evaluation of renewable energy systems in Mexico, particularly village-scale hybrid systems. This trip was made for the purpose of planning the details for the joint installation of a data acquisition system (DAS) on a recently completed PV/Wind/Diesel hybrid system in the village of Xcalac on the Southeast coast of the state of Quintana Roo, Mexico. The DAS installation will be made during the week of March 15, 1993. While in Mexico, discussions were also held with personnel from.the National Autonomous University of Mexico (UNAM) Solar Energy Laboratory and several private sector companies with regard to renewable energy project activities and technical and educational support needs in Mexico.

  10. Renewable energy systems advanced conversion technologies and applications

    CERN Document Server

    Luo, Fang Lin

    2012-01-01

    Energy conversion techniques are key in power electronics and even more so in renewable energy source systems, which require a large number of converters. Renewable Energy Systems: Advanced Conversion Technologies and Applications describes advanced conversion technologies and provides design examples of converters and inverters for renewable energy systems-including wind turbine and solar panel energy systems. Learn Cutting-Edge Techniques for Converters and Inverters Setting the scene, the book begins with a review of the basics of astronomy and Earth physics. It then systematically introduc

  11. Life-cycle analysis of renewable energy systems

    DEFF Research Database (Denmark)

    Sørensen, Bent

    1994-01-01

    An imlementation of life-cycle analysis (LCA) for energy systems is presented and applied to two renewable energy systems (wind turbines and building-integrated photovoltaic modules) and compared with coal plants......An imlementation of life-cycle analysis (LCA) for energy systems is presented and applied to two renewable energy systems (wind turbines and building-integrated photovoltaic modules) and compared with coal plants...

  12. Renewable energies - Fuel cell and hydrogen

    International Nuclear Information System (INIS)

    The objectives of the IPEN program are based on the MCT (Brazilian Ministry of Science and Technology) national program, contributing significantly to the national development in this area. The program comprises three main areas of interest: PEMFC (Proton Exchange Membrane Fuel Cell); SOFC(Solid Oxide Fuel Cell); and H2-Production, mainly from ethanol reforming

  13. Smart grid and renewable energy systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Guerrero, Josep M.

    2011-01-01

    The electrical energy consumption continues growing and more applications relay on electricity. We can expect that more 60 % of all energy consumption will be converted and used as electricity. Therefore, it is a demand that production, distribution and use of electrical energy are done as effici...... sources, wind energy and photovoltaics. Then main focus is on the power electronics and control technology for wind turbines as they are the largest renewable power contributor, allowing their penetration into a SmartGrid to be even higher in the future....... conventional, fossil based energy sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discus trends of the future grid infrastructure as well as the most emerging renewable energy...

  14. Limiting biomass consumption for heating in 100% renewable energy systems

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Connolly, David

    2012-01-01

    for other sectors, but while still enabling a 100% renewable energy system. The analyses of heating technologies shows that district heating (DH) systems are important in limiting the dependence on biomass and create cost effective solutions. DH systems are especially important in renewable energy...... such as large-scale solar thermal, large heat pumps, geothermal heat, industrial surplus heat, and waste incineration. Where the energy density in the building stock is not high enough for DH to be economical, geothermal heat pumps can be recommended for individual heating systems, even though biomass......The utilisation of biomass poses large challenges in renewable energy systems while buildings account for a substantial part of the energy supply even in 100% renewable energy systems. In this paper the focus is on how the heating sector can reduce its consumption of biomass, thus leaving biomass...

  15. Response of Non-Linear Systems to Renewal Impulses by Path Integration

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Iwankiewicz, R.

    The cell-to-cell mapping (path integration) technique has been devised for MDOF non-linear and non-hysteretic systems subjected to random trains of impulses driven by an ordinary renewal point process with gamma-distributed integer parameter interarrival times (an Erlang process). Since the renewal...... point process has not independent increments the state vector of the system, consisting of the generalized displacements and velocities, is not a Markov process. Initially it is shown how the indicated systems can be converted to an equivalent Poisson driven system at the expense of introducing...... additional discrete-valued state variables for which the stochastic equations are also formulated....

  16. The role of district heating in future renewable energy systems

    DEFF Research Database (Denmark)

    Lund, Henrik; Möller, Bernd; Mathiesen, Brian Vad;

    2010-01-01

    Based on the case of Denmark, this paper analyses the role of district heating in future Renewable Energy Systems. At present, the share of renewable energy is coming close to 20 per cent. From such point of departure, the paper defines a scenario framework in which the Danish system is converted...... as in a potential future system based 100 per cent on renewable energy....... to 100 per cent Renewable Energy Sources (RES) in the year 2060 including reductions in space heating demands by 75 per cent. By use of a detailed energy system analysis of the complete national energy system, the consequences in relation to fuel demand, CO2 emissions and cost are calculated for...

  17. Endothelial Cells Stimulate Self-Renewal and Expand Neurogenesis of Neural Stem Cells

    Science.gov (United States)

    Shen, Qin; Goderie, Susan K.; Jin, Li; Karanth, Nithin; Sun, Yu; Abramova, Natalia; Vincent, Peter; Pumiglia, Kevin; Temple, Sally

    2004-05-01

    Neural stem cells are reported to lie in a vascular niche, but there is no direct evidence for a functional relationship between the stem cells and blood vessel component cells. We show that endothelial cells but not vascular smooth muscle cells release soluble factors that stimulate the self-renewal of neural stem cells, inhibit their differentiation, and enhance their neuron production. Both embryonic and adult neural stem cells respond, allowing extensive production of both projection neuron and interneuron types in vitro. Endothelial coculture stimulates neuroepithelial cell contact, activating Notch and Hes1 to promote self-renewal. These findings identify endothelial cells as a critical component of the neural stem cell niche.

  18. Power Electronics and Reliability in Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke; Zhou, Dao

    2012-01-01

    Power Electronics are needed in almost all kind of renewable energy systems. It is used both for controlling the renewable source and also for interfacing to the load, which can be grid-connected or working in stand-alone mode. More and more efforts are put into making renewable energy systems...... better in terms of reliability in order to ensure a high availability of the power sources, in this case the knowledge of mission profile of a certain application is crucial for the reliability evaluation/design of power electronics. In this paper an overview on the power electronic circuits behind the...

  19. Power Electronics and Reliability in Renewable Energy Systems

    OpenAIRE

    Blaabjerg, Frede; Ma, Ke; Zhou, Dao

    2012-01-01

    Power Electronics are needed in almost all kind of renewable energy systems. It is used both for controlling the renewable source and also for interfacing to the load, which can be grid-connected or working in stand-alone mode. More and more efforts are put into making renewable energy systems better in terms of reliability in order to ensure a high availability of the power sources, in this case the knowledge of mission profile of a certain application is crucial for the reliability evaluati...

  20. The Potential of Renewable Energy Systems in China

    DEFF Research Database (Denmark)

    Liu, Wen; Lund, Henrik; Mathiesen, Brian Vad

    2009-01-01

    as well as reduce environmental pollution. To ensure energy security and mitigate climate changes the inappropriate energy consumption structure should be changed. As an alternative, a suitable infrastructure for the implementation of renewable energy may serve as a long-term sustainable possibility......This paper discusses the prospective of renewable energy in the process of sustainable development in China. Along with the high-speed economic development and increasing energy consumption, the Chinese Government faces a growing pressure to maintain the balance between energy supply and demand....... This paper analyses the current status and programming of renewable energy utilization in China and compares the potential of renewable energy sources and energy demand between China and Denmark. It proposes and discusses a forward-looking issue that is the perspective of a 100% renewable energy system...

  1. Integrated Nuclear-Renewable Energy Systems: Foundational Workshop Report

    International Nuclear Information System (INIS)

    The U.S. Department of Energy (DOE) recognizes the need to transform the energy infrastructure of the U.S. and elsewhere to systems that can drastically reduce environmental impacts in an efficient and economically viable manner while utilizing both hydrocarbon resources and clean energy generation sources. Thus, DOE is supporting research and development that could lead to more efficient utilization of clean energy generation sources, including renewable and nuclear options. A concept being advanced by the DOE Offices of Nuclear Energy (NE) and Energy Efficiency and Renewable Energy (EERE) is tighter coupling of nuclear and renewable energy sources in a manner that produces new energy currency for the combined electricity grid, industrial manufacturing, and the transportation energy sectors. This integration concept has been referred to as a ''hybrid system'' that is capable of providing the right type of energy, at the right time, in the right place. At the direction of DOE-NE and DOE-EERE leadership, project leads at Idaho National Laboratory (INL), National Renewable Energy Laboratory (NREL) and Massachusetts Institute of Technology (MIT) have identified and engaged stakeholders in discussing integrated energy systems that would optimize renewable and nuclear energy integration on a region-by-region basis. Subsequent work will entail conduct of technical, economic, environmental and socio-political evaluations of the leading integrated system options based on a set of criteria established with stakeholder input. The Foundational Workshop for Integrated Nuclear - Renewable Energy Systems was organized around the following objectives: 1. Identify and refine priority region-specific opportunities for integrated nuclear-renewable energy systems in the U.S.; 2. Select Figures of Merit (FOM) to rank and prioritize candidate systems; 3. Discuss enabling technology development needs; 4. Identify analysis requirements, capabilities and gaps to

  2. 100% Renewable energy systems, climate mitigation and economic growth

    DEFF Research Database (Denmark)

    Vad Mathiesen, Brian; Lund, Henrik; Karlsson, Kenneth Bernard

    2011-01-01

    implementing energy savings, renewable energy and more efficient conversion technologies can have positive socio-economic effects, create employment and potentially lead to large earnings on exports. If externalities such as health effects are included, even more benefits can be expected. 100% Renewable energy...... systems will be technically possible in the future, and may even be economically beneficial compared to the business-as-usual energy system. Hence, the current debate between leaders should reflect a combination of these two main challenges....

  3. Integrated Nuclear-Renewable Energy Systems: Foundational Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Shannon Bragg-Sitton; Richard Boardman; John Collins; Mark Ruth; Owen Zinaman; Charles Forsberg

    2014-08-01

    The U.S. Department of Energy (DOE) recognizes the need to transform the energy infrastructure of the U.S. and elsewhere to systems that can drastically reduce environmental impacts in an efficient and economically viable manner while utilizing both hydrocarbon resources and clean energy generation sources. Thus, DOE is supporting research and development that could lead to more efficient utilization of clean energy generation sources, including renewable and nuclear options. A concept being advanced by the DOE Offices of Nuclear Energy (NE) and Energy Efficiency and Renewable Energy (EERE) is tighter coupling of nuclear and renewable energy sources in a manner that produces new energy currency for the combined electricity grid, industrial manufacturing, and the transportation energy sectors. This integration concept has been referred to as a “hybrid system” that is capable of providing the right type of energy, at the right time, in the right place. At the direction of DOE-NE and DOE-EERE leadership, project leads at Idaho National Laboratory (INL), National Renewable Energy Laboratory (NREL) and Massachusetts Institute of Technology (MIT) have identified and engaged stakeholders in discussing integrated energy systems that would optimize renewable and nuclear energy integration on a region-by-region basis. Subsequent work will entail conduct of technical, economic, environmental and socio-political evaluations of the leading integrated system options based on a set of criteria established with stakeholder input. The Foundational Workshop for Integrated Nuclear – Renewable Energy Systems was organized around the following objectives: 1. Identify and refine priority region-specific opportunities for integrated nuclear-renewable energy systems in the U.S.; 2. Select Figures of Merit (FOM) to rank and prioritize candidate systems; 3. Discuss enabling technology development needs; 4. Identify analysis requirements, capabilities and gaps to estimate FOM for

  4. CrxOS maintains the self-renewal capacity of murine embryonic stem cells

    International Nuclear Information System (INIS)

    Embryonic stem (ES) cells maintain pluripotency by self-renewal. Several homeoproteins, including Oct3/4 and Nanog, are known to be key factors in maintaining the self-renewal capacity of ES cells. However, other genes required for the mechanisms underlying this process are still unclear. Here we report the identification by in silico analysis of a homeobox-containing gene, CrxOS, that is specifically expressed in murine ES cells and is essential for their self-renewal. ES cells mainly express the short isoform of endogenous CrxOS. Using a polyoma-based episomal expression system, we demonstrate that overexpression of the CrxOS short isoform is sufficient for maintaining the undifferentiated morphology of ES cells and stimulating their proliferation. Finally, using RNA interference, we show that CrxOS is essential for the self-renewal of ES cells, and provisionally identify foxD3 as a downstream target gene of CrxOS. To our knowledge, ours is the first delineation of the physiological role of CrxOS in ES cells.

  5. International Conference on Power Electronics and Renewable Energy Systems

    CERN Document Server

    Suresh, L; Dash, Subhransu; Panigrahi, Bijaya

    2015-01-01

    The book is a collection of high-quality peer-reviewed research papers presented in Proceedings of International Conference on Power Electronics and Renewable Energy Systems (ICPERES 2014) held at Rajalakshmi Engineering College, Chennai, India. These research papers provide the latest developments in the broad area of Power Electronics and Renewable Energy. The book discusses wide variety of industrial, engineering and scientific applications of the emerging techniques. It presents invited papers from the inventors/originators of new applications and advanced technologies.

  6. WNT signaling regulates self-renewal and differentiation of prostate cancer cells with stem cell characteristics

    Institute of Scientific and Technical Information of China (English)

    Isabelle Bisson; David M Prowse

    2009-01-01

    Prostate cancer cells with stem cell characteristics were identified in human prostate cancer cell lines by their abil-ity to form from single cells self-renewing prostaspheres in non-adherent cultures. Prostaspheres exhibited heteroge-neous expression of proliferation, differentiation and stem cell-associated makers CD44, ABCG2 and CD133. Treat-ment with WNT inhibitors reduced both prostasphere size and self-renewal, In contrast, addition of Wnt3a caused increased prostasphere size and self-renewal, which was associated with a significant increase in nuclear β-catenin, keratin 18, CD133 and CD44 expression. As a high proportion of LNCaP and C4-2B cancer cells express androgen receptor we determined the effect of the androgen receptor antagonist bicalutamide. Androgen receptor inhibition reduced prostasphere size and expression of PSA, but did not inhibit prostasphere formation. These effects are con-sistent with the androgen-independent self-renewal of cells with stem cell characteristics and the androgen-dependent proliferation of transit amplifying cells. As the canonical WNT signaling effector β-catenin can also associate with the androgen receptor, we propose a model for tumour propagation involving a balance between WNT and androgen re-ceptor activity. That would affect the self-renewal of a cancer cell with stem cell characteristics and drive transit am-plifying cell proliferation and differentiation. In conclusion, we provide evidence that WNT activity regulates the self-renewal of prostate cancer cells with stem cell characteristics independently of androgen receptor activity. Inhibition of WNT signaling therefore has the potential to reduce the self-renewal of prostate cancer cells with stem cell charac-teristics and improve the therapeutic outcome.

  7. Management of a power system based on renewable energy

    Directory of Open Access Journals (Sweden)

    Ronay Karoly

    2012-06-01

    Full Text Available This article main purpose is to highlight the main advantage of the hardware and software implementation for an energy management system based on renewable energy sources. By using implemented and dedicated hardware and software the evolution of energy production and consumption can be monitored. The advantages of such system are highlighted by the results obtained from experimental simulations. An experimental model for the power system based on renewable energy sources was implemented, where the actual status of the system in different situations when the equipments change their own statuses can be shown.

  8. Power Electronics for Renewable Energy Systems - Status and Trends

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke; Yang, Yongheng

    2014-01-01

    In the past few decades, the energy paradigms in many countries are experiencing significant change from fossil-based resources to cleaner renewables. It is expected that the scenario of highly penetrated renewables is going to be further enhanced. This requires that the production, distribution...... electronics in generation, transmission/distribution and end-user application, together with advanced controls, can pave the way for renewable energy resources. In view of this, some of the most promising renewable candidates like wind power and photovoltaic, which are becoming a significant part in the...... and use of the energy to be as technological efficient as possible, and incentives to save energy at the end-user should also be strengthened. In order to realize the transition smoothly and effectively, power conversion systems will continue to play an essential role. Using highly efficient power...

  9. Simulation of hybrid renewable microgeneration systems for variable electricity prices

    International Nuclear Information System (INIS)

    This paper addresses a hybrid renewable system that consists of a micro-Combined Cooling Heat and Power (CCHP) unit and a solar energy conversion device. In addition to a traditional PV system, a High Concentrator Photovoltaic (HCPV) device, the design of which is suitable for building integration application, was also modelled and embedded in the hybrid system. The work identifies the optimal management strategies for the hybrid renewable system in an effort to minimise the primary energy usage, the carbon dioxide emissions and the operational costs for variable electricity prices that result from the day-ahead electricity market. An “ad hoc” model describes the performance of the HCPV module, PV and Internal Combustion Engine, whilst the other units were simulated based on their main characteristic parameters. The developed algorithm was applied to three different building typologies. The results indicate that the best configuration is the hybrid renewable system with PV, which can provide a yearly primary energy reduction of between 20% and 30% compared to separate production. The hybrid renewable system with HCPV becomes competitive with the PV technology when the level of solar radiation is high. - Highlights: • The paper addresses a hybrid renewable system that consists of a micro-CCHP unit and a solar energy conversion device. • Both PV and High Concentrator Photovoltaic (HCPV) systems have been modelled and embedded in the hybrid system. • The work identifies the optimal management strategies for variable electricity prices. • Hybrid renewable systems provide a yearly primary energy reduction of between 20% and 30% compared to separate production. • When the level of solar radiation is high, HCPV becomes competitive with the PV technology

  10. Renewable energy systems for remote areas in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, D.; Lloyd, C.R. [Centre for Appropriate Technology, Alice Springs (Australia)

    2001-03-01

    It has been long thought that the northern and central regions of Australia are ideal places for the installation of remote area power supplies (RAPS) based on renewable energy. In particular the solar regime in these areas is among the highest in the world. The Centre of Appropriate Technology has been undertaking a project, as part of the Australian Cooperative Research Centre for Renewable Energy research program, to look at the viability of renewable energy systems in remote areas of northern and central Australia. The study has involved compiling a database of existing knowledge of renewables in these areas combined with a set of site visits and case studies to look at both community attitudes to renewable energy and the actual operation of the systems. The study started in early 1997 and is due to be completed towards the end of 1999. The present paper outlines the logistics of the study and some of the results. The emphasis so far has been on wind and solar systems (including hybrid diesel systems) in Aboriginal communities. Some work has progressed for systems in pastoral properties and tourist ventures. The fieldwork to date has covered northern South Australia and the Northern Territory. Further fieldwork will occur in northern Queensland and Western Australia in mid 1999. (author)

  11. 100% Renewable Energy Systems in Project Future Climate

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad

    2009-01-01

    , create employment and potentially lead to large earnings on exports. If externalities such as health effects etc. are included, even more benefits can be expected. 100 per cent renewable energy systems will be technically possible in the future, and may even be economically beneficial compared to the...... energy system by the year 2050 are presented. Two short term transition target years in the process towards this goal are analysed for 2015 and 2030. The analyses reveal that implementing energy savings, renewable energy and more efficient conversion technologies can have positive socioeconomic effects...... business-as-usual energy system. Hence the current debate between leaders should reflect a combination of these two main challenges....

  12. Nuclear-renewable hybrid energy systems: Opportunities, interconnections, and needs

    International Nuclear Information System (INIS)

    Highlights: • We explore nuclear-renewable hybrid energy systems. • They will increase grid flexibility, reduce greenhouse gas emissions, and optimize capital use. • Six aspects of interaction are identified and discussed. • System-level aspects are also discussed. • Gaps and research needs are identified to promote further exploration of the topic. - Abstract: As the U.S. energy system evolves, the amount of electricity from variable-generation sources is likely to increase, which could result in additional times when electricity demand is lower than available production. Thus, purveyors of technologies that traditionally have provided base-load electricity—such as nuclear power plants—can explore new operating procedures to deal with the associated market signals. Concurrently, innovations in nuclear reactor design coupled with sophisticated control systems now allow for more complex apportionment of heat within an integrated system such as one linked to energy-intensive chemical processes. This paper explores one opportunity – nuclear-renewable hybrid energy systems. These are defined as integrated facilities comprised of nuclear reactors, renewable energy generation, and industrial processes that can simultaneously address the need for grid flexibility, greenhouse gas emission reductions, and optimal use of investment capital. Six aspects of interaction (interconnections) between elements of nuclear-renewable hybrid energy systems are identified: Thermal, electrical, chemical, hydrogen, mechanical, and information. Additionally, system-level aspects affect selection, design, and operation of this hybrid system type. Throughout the paper, gaps and research needs are identified to promote further exploration of the topic

  13. Ireland's pathway towards a 100% renewable energy-system:

    DEFF Research Database (Denmark)

    Connolly, David; Leahy, Martin; Lund, Henrik;

    2009-01-01

    Ireland has an abundant supply of renewable energy, a dangerous reliance on imported fossil fuels, as well as very demanding energy and CO2 targets to reach. All of these indicate that a major alternation to the current energy system is necessary, especially an increase in the utilisation of...... renewable energy. Consequently, this study presents the first step towards identifying how this transition may be achieved for the Republic of Ireland. The energy- systems-analysis tool, EnergyPLAN, was chosen for this investigation, as it accounts for all sectors that need to be considered for integrating...... results in this paper illustrate the four scenarios of a 100% renewable energy system for Ireland: a biomass, hydrogen, electricity and combination scenario. However, these results have been completed based on numerous assumptions that will need to be investigated in future work, before a serious roadmap...

  14. EVermont Renewable Hydrogen Production and Transportation Fueling System

    Energy Technology Data Exchange (ETDEWEB)

    Garabedian, Harold T.

    2008-03-30

    A great deal of research funding is being devoted to the use of hydrogen for transportation fuel, particularly in the development of fuel cell vehicles. When this research bears fruit in the form of consumer-ready vehicles, will the fueling infrastructure be ready? Will the required fueling systems work in cold climates as well as they do in warm areas? Will we be sure that production of hydrogen as the energy carrier of choice for our transit system is the most energy efficient and environmentally friendly option? Will consumers understand this fuel and how to handle it? Those are questions addressed by the EVermont Wind to Wheels Hydrogen Project: Sustainable Transportation. The hydrogen fueling infrastructure consists of three primary subcomponents: a hydrogen generator (electrolyzer), a compression and storage system, and a dispenser. The generated fuel is then used to provide transportation as a motor fuel. EVermont Inc., started in 1993 by then governor Howard Dean, is a public-private partnership of entities interested in documenting and advancing the performance of advanced technology vehicles that are sustainable and less burdensome on the environment, especially in areas of cold climates, hilly terrain and with rural settlement patterns. EVermont has developed a demonstration wind powered hydrogen fuel producing filling system that uses electrolysis, compression to 5000 psi and a hydrogen burning vehicle that functions reliably in cold climates. And that fuel is then used to meet transportation needs in a hybrid electric vehicle whose internal combustion engine has been converted to operate on hydrogen Sponsored by the DOE EERE Hydrogen, Fuel Cells & Infrastructure Technologies (HFC&IT) Program, the purpose of the project is to test the viability of sustainably produced hydrogen for use as a transportation fuel in a cold climate with hilly terrain and rural settlement patterns. Specifically, the project addresses the challenge of building a renewable

  15. Power electronics for renewable energy systems, transportation and industrial applications

    CERN Document Server

    Abu-Rub, Haitham; Al-Haddad, Kamal

    2014-01-01

    Compiles current research into the analysis and design of power electronic converters for industrial applications and renewable energy systems, presenting modern and future applications of power electronics systems in the field of electrical vehicles With emphasis on the importance and long-term viability of Power Electronics for Renewable Energy this book brings together the state of the art knowledge and cutting-edge techniques in various stages of research.  The topics included are not currently available for practicing professionals and aim to enable the reader to directly apply the know

  16. Adhesion-mediated self-renewal abilities of Ph+ blastoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Funayama, Keiji; Saito-Kurimoto, Yumi [Department of Integrative Bioscience and Biomedical Engineering, Waseda University, 4-3-1 Ohkubo, Shinjuku-ku, Tokyo 169-555 (Japan); Ebihara, Yasuhiro [Institute of Medical Science, University of Tokyo, 4-6-1 Shirokenedai, Minato-ku, Tokyo (Japan); Shimane, Miyuki; Nomura, Hitoshi [Department of Integrative Bioscience and Biomedical Engineering, Waseda University, 4-3-1 Ohkubo, Shinjuku-ku, Tokyo 169-555 (Japan); Tsuji, Ko-ichiro [Institute of Medical Science, University of Tokyo, 4-6-1 Shirokenedai, Minato-ku, Tokyo (Japan); Asano, Shigetaka, E-mail: asgtkmd@waseda.jp [Department of Integrative Bioscience and Biomedical Engineering, Waseda University, 4-3-1 Ohkubo, Shinjuku-ku, Tokyo 169-555 (Japan)

    2010-05-28

    The Philadelphia chromosome-positive blastoma, maintained by serial subcutaneous transplantation in nude mice, is a highly proliferating biological mass consisting of homogenous CD34{sup +}CD38{sup -} myeloblastoid cells. These cells newly evolved from pluripotent leukemia stem cells of chronic myeloid leukemia in the chronic phase. Therefore, this mass may provide a unique tool for better understanding cellular and molecular mechanisms of self-renewal of leukemia stem cells. In this paper, we demonstrated that intravenously injected blastoma cells can cause Ph+ blastic leukemia with multiple invasive foci in NOD/SCID mice but not in nude mice. In addition, using an in vitro culture system, we clearly showed that blastoma cell adhesion to OP9 stromal cells accelerates blastoma cell proliferation that is associated with up-regulation of BMI1 gene expression; increased levels of {beta}-catenin and the Notch1 intra-cellular domain; and changed the expression pattern of variant CD44 forms, which are constitutively expressed in these blastoma cells. These findings strongly suggest that adhesion of leukemic stem cells to stromal cells via CD44 might be indispensable for their cellular defense against attack by immune cells and for maintenance of their self-renewal ability.

  17. Scientific Approach to Renewable Energy Through Solar Cells

    Science.gov (United States)

    Rao, M. C.

    Renewable energy is increasingly viewed as critically important globally. Solar cells convert the energy of the sun into electricity. The method of converting solar energy to electricity is pollution free, and appears a good practical solution to the global energy problems. Energy policies have pushed for different technologies to decrease pollutant emissions and reduce global climate change. Photovoltaic technology, which utilizes sunlight to generate energy, is an attractive alternate energy source because it is renewable, harmless and domestically secure. Transparent conducting metal oxides, being n-type were used extensively in the production of heterojunction cells using p-type Cu2O. The long held consensus is that the best approach to improve cell efficiency in Cu2O-based photovoltaic devices is to achieve both p- and n-type Cu2O and thus p-n homojunction of Cu2O solar cells. Silicon, which, next to oxygen, is the most represented element in the earth's crust, is used for the production of monocrystalline silicon solar cells. Silicon is easily obtained and processed and it is not toxic and does not form compounds that would be environmentally harmful. In contemporary electronic industry silicon is the main semiconducting element. Thin-film cadmium telluride (CdTe) solar cells are the basis of a significant technology with major commercial impact on solar energy production. Polycrystalline thin-film solar cells such as CuInSe2 (CIS), Cu (In, Ga) Se2 (CIGS) and CdTe compound semiconductors are important for terrestrial applications because of their high efficiency, long-term stable performance and potential for low-cost production. Highest record efficiencies of 19.2% for CIGS and 16.5% for CdTe have been achieved.

  18. Renewable regenerative energy systems: Practical integration challenges. Paper no. IGEC-1-093

    International Nuclear Information System (INIS)

    Interest in renewable energy systems that employ regenerative components to enable intermittent energy sources to service time varying loads is growing. The overall performance of these systems is intimately linked to the choice of the energy storage media and the efficiency of the energy conversion devices. Recent advances in electrolyser and fuel cell technologies may make small-scale hydrogen buffered renewable energy systems a practical reality in the near term. A research team at the University of Victoria - Institute for Integrated Energy Systems (IESVic) is developing a flexible distributed, laboratory-scale energy system called IRENE (Integrated Renewable Energy Experiment). The initial goal of this research is to explore the potential for constructing a regenerative energy system using early commercial and precommercial hydrogen storage and fuel cell energy conversion devices. Once implemented, research efforts will focus on the dynamic interactions between system elements that arise while servicing short-term transient supply/demand transfer functions. Although simple in concept, numerous integration issues have been encountered while developing IRENE. The fundamental integration issues must be addressed if small-scale renewable regenerative systems are to displace conventional fossil fuel based solutions in the future. The motivation for, the components used, and the practical lessons learned though the development of IRENE will be discussed. (author)

  19. 100% Renewable energy systems, climate mitigation and economic growth

    DEFF Research Database (Denmark)

    Vad Mathiesen, Brian; Lund, Henrik; Karlsson, Kenneth Bernard

    2011-01-01

    Greenhouse gas mitigation strategies are generally considered costly with world leaders often engaging in debate concerning the costs of mitigation and the distribution of these costs between different countries. In this paper, the analyses and results of the design of a 100% renewable energy...... implementing energy savings, renewable energy and more efficient conversion technologies can have positive socio-economic effects, create employment and potentially lead to large earnings on exports. If externalities such as health effects are included, even more benefits can be expected. 100% Renewable energy...... systems will be technically possible in the future, and may even be economically beneficial compared to the business-as-usual energy system. Hence, the current debate between leaders should reflect a combination of these two main challenges....

  20. Optimal generation scheduling for renewable microgrids using hydrogen storage systems

    OpenAIRE

    Petrollese, Mario

    2015-01-01

    The topic of this thesis is the development of a tool for an optimal energy management strategy (EMS) of the generators and energy storage systems constituent microgrids, both grid-connected or isolated (stand-alone power system) powered by Renewable Energy Sources (RES). In particular, a novel control system is designed based on the resolution of the unit commitment problem. For each time step, the proposed control system compares the expected power produced by the renewabl...

  1. Molecular mechanisms controlling asymmetric and symmetric self-renewal of cancer stem cells

    OpenAIRE

    Yoo, Young Dong; Kwon, Yong Tae

    2015-01-01

    Cancer stem cells (CSCs), or alternatively called tumor initiating cells (TICs), are a subpopulation of tumor cells, which possesses the ability to self-renew and differentiate into bulk tumor mass. An accumulating body of evidence suggests that CSCs contribute to the growth and recurrence of tumors and the resistance to chemo- and radiotherapy. CSCs achieve self-renewal through asymmetric division, in which one daughter cell retains the self-renewal ability, and the other is destined to diff...

  2. Web based system for renewable energy sources assessment

    International Nuclear Information System (INIS)

    The RESAssess software is developed to assist in the preliminary assessment of potential renewable energy projects. The first release includes water pumping solar systems, passive solar systems, wind, and geothermal energy and biomass. The program guides the users in the design of their systems, by providing initial estimates. By changing the system’s parameters, users are able to quickly screen an effective technology and system size depending on load, climatic conditions, and season of use. This paper describes scope of models (radiation, wind, geothermal, heat transfer) used to predict energy production from energy resource systems, climatic variables and system parameters and software technology for realising the project. Keywords: Energy projects, Renewable energy, Web system

  3. Renewable energy credit driven wind power growth for system reliability

    International Nuclear Information System (INIS)

    Environmental concerns over electric power generation from conventional sources has led to widespread public support for renewable energy sources. Governments throughout the world have responded by providing various forms of financial incentives to promote power generation from renewable energy sources. The rapid growth of wind power since the last decade has primarily been driven by governmental subsidies. Long-term growth of wind power should, however, be driven by sustainable market mechanisms. A potential solution is to recognize monetary values to the environmental benefits from renewable energy sources, and to specify targets for their growth. The environmental benefits from wind sources can be leveraged to allow market competition of these sources with the less costly conventional generating sources. A probabilistic method to evaluate the impact of renewable energy credit and wind penetration level on the cost and adequacy of power generating systems is presented in this paper. The technique incorporates reliability and economic analysis and is applied to a published test system to illustrate the results and their influence on key system variables. The paper provides useful information to system planners and policy makers on wind energy application in electric power systems. (author)

  4. LCA of renewable energy for electricity generation systems. A review

    International Nuclear Information System (INIS)

    Sustainable development requires methods and tools to measure and compare the environmental impacts of human activities for various products (goods and services). Providing society with goods and services contributes to a wide range of environmental impacts. Environmental impacts include emissions into the environment and the consumption of resources as well as other interventions such as land use, etc. Life cycle assessment (LCA) is a technique for assessing environmental loads of a product or a system. The aim of this paper is to review existing energy and CO2 life cycle analyses of renewable sources based electricity generation systems. The paper points out that carbon emission from renewable energy (RE) systems are not nil, as is generally assumed while evaluating carbon credits. Further the range of carbon emissions from RE systems have been found out from existing literature and compared with those from fossil fuel based systems, so as to assist in a rational choice of energy supply systems. (author)

  5. Forecasting US renewables in the national energy modelling system

    International Nuclear Information System (INIS)

    The Energy information Administration (EIA) of the US Department of Energy (DOE) forecasts US renewable energy supply and demand in the context of overall energy markets using the National Energy Modelling System (NEMS). Renewables compete with other supply and demand options within the residential, commercial, industrial, transportation, and electricity sectors of the US economy. NEMS forecasts renewable energy for grid-connected electricity production within the Electricity Market Module (EM), and characterizes central station biomass, geothermal, conventional hydroelectric, municipal solid waste, solar thermal, solar photovoltaic, and wind-powered electricity generating technologies. EIA's Annual Energy Outlook 1998, projecting US energy markets, forecasts marketed renewables to remain a minor part of US energy production and consumption through to 2020. The USA is expected to remain primarily a fossil energy producer and consumer throughout the period. An alternative case indicates that biomass, wind, and to some extent geothermal power would likely increase most rapidly if the US were to require greater use of renewables for power supply, though electricity prices would increase somewhat. (author)

  6. Nuclear-Renewable Hybrid Energy System Market Analysis Plans

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Mark

    2016-06-09

    This presentation describes nuclear-renewable hybrid energy systems (N-R HESs), states their potential benefits, provides figures for the four tightly coupled N-R HESs that NREL is currently analyzing, and outlines the analysis process that is underway.

  7. A two level decentralized distribution system with compound renewal demand

    OpenAIRE

    2002-01-01

    In this paper we consider a two level decentralized distribution system, consisting of one warehouse and N retailers. The warehouse and each retailer follows each his own (s,nQ) order policy. We extended the models as known in the literature to compound renewal demand.

  8. Design for Reliability of Power Electronics in Renewable Energy Systems

    DEFF Research Database (Denmark)

    Ma, Ke; Yang, Yongheng; Wang, Huai;

    2014-01-01

    Power electronics is the enabling technology for maximizing the power captured from renewable electrical generation, e.g., the wind and solar technology, and also for an efficient integration into the grid. Therefore, it is important that the power electronics are reliable and do not have too many...... failures during operation which otherwise will increase cost for operation, maintenance and reputation. Typically, power electronics in renewable electrical generation has to be designed for 20–30 years of operation, and in order to do that, it is crucial to know about the mission profile of the power...... electronics technology as well as to know how the power electronics technology is loaded in terms of temperature and other stressors relevant, to reliability. Hence, this chapter will show the basics of power electronics technology for renewable energy systems, describe the mission profile of the technology...

  9. Photoactivated Fuel Cells (PhotoFuelCells. An alternative source of renewable energy with environmental benefits

    Directory of Open Access Journals (Sweden)

    Stavroula Sfaelou

    2016-03-01

    Full Text Available This work is a short review of Photoactivated Fuel Cells, that is, photoelectrochemical cells which consume an organic or inorganic fuel to produce renewable electricity or hydrogen. The work presents the basic features of photoactivated fuel cells, their modes of operation, the materials, which are frequently used for their construction and some ideas of cell design both for electricity and solar hydrogen production. Water splitting is treated as a special case of photoactivated fuel cell operation.

  10. Photoactivated Fuel Cells (PhotoFuelCells). An alternative source of renewable energy with environmental benefits

    OpenAIRE

    Stavroula Sfaelou; Panagiotis Lianos

    2016-01-01

    This work is a short review of Photoactivated Fuel Cells, that is, photoelectrochemical cells which consume an organic or inorganic fuel to produce renewable electricity or hydrogen. The work presents the basic features of photoactivated fuel cells, their modes of operation, the materials, which are frequently used for their construction and some ideas of cell design both for electricity and solar hydrogen production. Water splitting is treated as a special case of photoactivated fuel cell op...

  11. Id1 restrains myeloid commitment, maintaining the self-renewal capacity of hematopoietic stem cells

    OpenAIRE

    Jankovic, Vladimir; Ciarrocchi, Alessia; Boccuni, Piernicola; Deblasio, Tony; Benezra, Robert; Nimer, Stephen D.

    2007-01-01

    Appropriate hematopoietic stem cell (HSC) self-renewal reflects the tight regulation of cell cycle entry and lineage commitment. Here, we show that Id1, a dominant-negative regulator of E protein transcription factors, maintains HSC self-renewal by preserving the undifferentiated state. Id1-deficient HSCs show increased cell cycling, by BrdU incorporation in vivo, but fail to efficiently self-renew, leading to low steady-state HSC numbers and premature exhaustion in serial bone marrow transpl...

  12. Risk management of non-renewable energy systems

    CERN Document Server

    Verma, Ajit Kumar; Muruva, Hari Prasad

    2015-01-01

    This book describes the basic concepts of risk and reliability with detailed descriptions of the different levels of probabilistic safety assessment of nuclear power plants (both internal and external). The book also maximizes readers insights into time dependent risk analysis through several case studies, whilst risk management with respect to non renewable energy sources is also explained. With several advanced reactors utilizing the concept of passive systems, the reliability estimation of these systems are explained in detail with the book providing a reliability estimation of components through mechanistic model approach. This book is useful for advanced undergraduate and post graduate students in nuclear engineering, aerospace engineering, industrial engineering, reliability and safety engineering, systems engineering and applied probability and statistics. This book is also suitable for one-semester graduate courses on risk management of non renewable energy systems in all conventional engineering bran...

  13. Heating technologies for limiting biomass consumption in 100% renewable energy systems

    OpenAIRE

    Mathiesen, Brian Vad; Lund, Henrik; Connolly, David

    2011-01-01

    The utilisation of biomass poses large challenges in renewable energy systems and buildings account for a substantial part of the energy supply also in 100% renewable energy systems. The analyses of heating technologies show that district heating systems are especially important in limiting the dependence on biomass resources and to create cost effective systems. District heating systems are especially important in renewable energy systems with large amounts of fluctuating renewable energy so...

  14. Technoeconomic analysis of renewable hydrogen production, storage, and detection systems

    Energy Technology Data Exchange (ETDEWEB)

    Mann, M.K.; Spath, P.L.; Kadam, K. [National Renewable Energy Lab., Golden, CO (United States)

    1996-10-01

    Technical and economic feasibility studies of different degrees of completeness and detail have been performed on several projects being funded by the Department of Energy`s Hydrogen Program. Work this year focused on projects at the National Renewable Energy Laboratory, although analyses of projects at other institutions are underway or planned. Highly detailed analyses were completed on a fiber optic hydrogen leak detector and a process to produce hydrogen from biomass via pyrolysis followed by steam reforming of the pyrolysis oil. Less detailed economic assessments of solar and biologically-based hydrogen production processes have been performed and focused on the steps that need to be taken to improve the competitive position of these technologies. Sensitivity analyses were conducted on all analyses to reveal the degree to which the cost results are affected by market changes and technological advances. For hydrogen storage by carbon nanotubes, a survey of the competing storage technologies was made in order to set a baseline for cost goals. A determination of the likelihood of commercialization was made for nearly all systems examined. Hydrogen from biomass via pyrolysis and steam reforming was found to have significant economic potential if a coproduct option could be co-commercialized. Photoelectrochemical hydrogen production may have economic potential, but only if low-cost cells can be modified to split water and to avoid surface oxidation. The use of bacteria to convert the carbon monoxide in biomass syngas to hydrogen was found to be slightly more expensive than the high end of currently commercial hydrogen, although there are significant opportunities to reduce costs. Finally, the cost of installing a fiber-optic chemochromic hydrogen detection system in passenger vehicles was found to be very low and competitive with alternative sensor systems.

  15. Electrical Energy Storage for Renewable Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Helms, C. R.; Cho, K. J.; Ferraris, John; Balkus, Ken; Chabal, Yves; Gnade, Bruce; Rotea, Mario; Vasselli, John

    2012-08-31

    This program focused on development of the fundamental understanding necessary to significantly improve advanced battery and ultra-capacitor materials and systems to achieve significantly higher power and energy density on the one hand, and significantly lower cost on the other. This program spanned all the way from atomic-level theory, to new nanomaterials syntheses and characterization, to system modeling and bench-scale technology demonstration. Significant accomplishments are detailed in each section. Those particularly noteworthy include: • Transition metal silicate cathodes with 2x higher storage capacity than commercial cobalt oxide cathodes were demonstrated. • MnO₂ nanowires, which are a promising replacement for RuO₂, were synthesized • PAN-based carbon nanofibers were prepared and characterized with an energy density 30-times higher than current ultracapacitors on the market and comparable to lead-acid batteries • An optimization-based control strategy for real-time power management of battery storage in wind farms was developed and demonstrated. • PVDF films were developed with breakdown strengths of > 600MVm⁻¹, a maximum energy density of approximately 15 Jcm⁻³, and an average dielectric constant of 9.8 (±1.2). Capacitors made from these films can support a 10-year lifetime operating at an electric field of 200 MV m⁻¹. This program not only delivered significant advancements in fundamental understanding and new materials and technology, it also showcased the power of the cross-functional, multi-disciplinary teams at UT Dallas and UT Tyler for such work. These teams are continuing this work with other sources of funding from both industry and government.

  16. Pressure retarded osmosis as a controlling system for traditional renewables

    Science.gov (United States)

    Carravetta, Armando; Fecarotta, Oreste; La Rocca, Michele; Martino, Riccardo

    2015-04-01

    Pressure retarded osmosis (PRO) is a viable but still not diffused form of renewable energy (see Maisonneuve et al., 2015 for a recent literature review). In PRO, water from a low salinity feed solution permeates through a membrane into a pressurized, high salinity draw solution, giving rise to a positive pressure drop; then energy is obtained by depressurizing the permeate through a hydro-turbine and brackish water is discharged. Many technological, environmental and economical aspects are obstacles in the diffusion of PRO, like the vulnerability of the membranes to fouling, the impact of the brackish water on the local marine environment, the high cost of membranes, etc. We are interested in the use of PRO as a combined form of energy with other renewable energy source like solar, wind or mini hydro in water supply networks (WSN). For the wide diffusion of renewables one of the major concerns of commercial power companies is to obtain very stable form of energy to comply with prescriptions of electricity grid operators and with the instant energy demand curve. Renewables are generally very variable form of energy, for the influence of climatic conditions on available power, and of the fluctuation in water demand in WSN. PRO is a very flexible technology where with appropriate turbines and control system power can be varied continuously to compensate for variation of other source of energy. Therefore, PRO is suitable to be used as a balancing system for commercial power system. We will present a simulation of the performance of a PRO used in combination with three different renewables. In the first two scenarios PRO compensate the difference between energy demand and energy production of a solar power plant and hydro power plant in a WSN. In the third scenario PRO is used to compensate daily variation of energy production in a wind power plant. Standard curves of energy production and energy demand for southern Italy are used. In order to control PRO production an

  17. Design of smart power grid renewable energy systems

    CERN Document Server

    Keyhani, Ali

    2011-01-01

    To address the modeling and control of smart grid renewable energy system into electric power systems, this book integrates three areas of electrical engineering: power system engineering, control systems engineering and power electronics  The approach to the integration of these three areas differs from classical methods. Due to complexity of this task, the author has decided to present the basic concepts, and then present a simulation test bed in matlab to use these concepts to solve a basic problem in development of smart grid energy system. Therefore, each chapter has three parts: first a

  18. Power electronics - The key technology for Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke; Yang, Yongheng

    2014-01-01

    and effectively, energy conversion systems, currently based on power electronics technology, will again play an essential role in this energy paradigm shift. Using highly efficient power electronics in power generation, power transmission/distribution and end-user application, together with advanced control...... solutions, can pave the way for renewable energies. In light of this, some of the most emerging renewable energies, e.g. wind energy and photovoltaic, which by means of power electronics are changing character as a major part in the electricity generation, are explored in this paper. Issues like technology...... development, implementation, power converter technologies, control of the systems, and synchronization are addressed. Special focuses are paid on the future trends in power electronics for those systems like how to lower the cost of energy and to develop emerging power devices and better reliability tool....

  19. miRNAs regulate stem cell self-renewal and differentiation

    OpenAIRE

    Yu, Zuoren; Li, Yuan; Fan, Huimin; Liu, Zhongmin; Pestell, Richard G.

    2012-01-01

    Stem cells undergo symmetric and asymmetric divisions to generate differentiated cells and more stem cells. The balance between self-renewal and differentiation of stem cells is controlled by transcription factors, epigenetic regulatory networks, and microRNAs (miRNAs). Herein the miRNA involvement in the regulation of stem cell self-renewal and differentiation is summarized. miRNA contribution to malignancy through regulating cancer stem cells is described. In addition, the reciprocal associ...

  20. Integrating renewable energy sources in the Portuguese power system

    International Nuclear Information System (INIS)

    The integration of large amounts of renewable energy is an important challenge for the future management of electric systems, since it affects the operation of the electric power system and the design of the transmission and distribution network infrastructure. This is specially due to the connection requirements of the renewable energy technologies, to the extension and adjustment of the grid infrastructure and to the identification of new solutions for operational reserve, in order to maintain the overall system flexibility and security. In this paper, the impact of high penetration of intermittent energy sources, expected in long term in the Portuguese Power System, is analysed and the operational reserve requirements to accomplish a reliable and reasonable electrical energy supply are identified. It was concluded that pumped storage power plants, special power plants with regulating capabilities, will have an important task to provide the operational reserve requirements of the Portuguese Power System. This technology assumes a fundamental role not only to ensure the adequate levels of security of supply but also to allow the maximum exploitation of the installed capacity in renewable energy sources. (authors)

  1. A planarian p53 homolog regulates proliferation and self-renewal in adult stem cell lineages.

    Science.gov (United States)

    Pearson, Bret J; Sánchez Alvarado, Alejandro

    2010-01-01

    The functions of adult stem cells and tumor suppressor genes are known to intersect. However, when and how tumor suppressors function in the lineages produced by adult stem cells is unknown. With a large population of stem cells that can be manipulated and studied in vivo, the freshwater planarian is an ideal system with which to investigate these questions. Here, we focus on the tumor suppressor p53, homologs of which have no known role in stem cell biology in any invertebrate examined thus far. Planaria have a single p53 family member, Smed-p53, which is predominantly expressed in newly made stem cell progeny. When Smed-p53 is targeted by RNAi, the stem cell population increases at the expense of progeny, resulting in hyper-proliferation. However, ultimately the stem cell population fails to self-renew. Our results suggest that prior to the vertebrates, an ancestral p53-like molecule already had functions in stem cell proliferation control and self-renewal. PMID:20040488

  2. A smart monitoring infrastructure design for distributed renewable energy systems

    International Nuclear Information System (INIS)

    Highlights: • A smart grid model for renewable energy sources is proposed in this study. • The renewable energy conversion system is constituted with solar plants and full bridge inverter. • The power line communication is performed with QPSK modulation. • The transmission line that has 25 km length is modelled with real-time parameters. • The efficiency of system is analysed by comparing transmitted and received data. - Abstract: The automatic meter reading is essentially required in renewable grids as in conventional grids. It is intended to propose a reliable measurement system that is validated in a photovoltaic power system to meet the requirement of a renewable grid. In the presented study, the photovoltaic plants are controlled by using a widely known maximum power point tracking algorithm that is named as “Perturb and Observe”. The distribution line at the output of inverter is modelled according to realistic parameters of 25 km line. Besides carrying the generated line voltage, the grid is used as a transmission medium for the generated power measurements of photovoltaic plants and power consumptions of load plants separately. The modem constituting the power line communication manages the dual-channel transfer and transmits the consumed energy ratios of the load plants. One of the modems is located at the output of voltage source inverter and the other one of the load plants. The power consumption values of each load plants are individually measured and successfully transmitted to monitoring section in the modelled system. The obtained data that is only used for monitoring in this application can also be evaluated for automatic meter reading applications

  3. Design, analysis, operation, and advanced control of hybrid renewable energy systems

    Science.gov (United States)

    Whiteman, Zachary S.

    Because using non-renewable energy systems (e.g., coal-powered co-generation power plants) to generate electricity is an unsustainable, environmentally hazardous practice, it is important to develop cost-effective and reliable renewable energy systems, such as photovoltaics (PVs), wind turbines (WTs), and fuel cells (FCs). Non-renewable energy systems, however, are currently less expensive than individual renewable energy systems (IRESs). Furthermore, IRESs based on intermittent natural resources (e.g., solar irradiance and wind) are incapable of meeting continuous energy demands. Such shortcomings can be mitigated by judiciously combining two or more complementary IRESs to form a hybrid renewable energy system (HRES). Although previous research efforts focused on the design, operation, and control of HRESs has proven useful, no prior HRES research endeavor has taken a systematic and comprehensive approach towards establishing guidelines by which HRESs should be designed, operated, and controlled. The overall goal of this dissertation, therefore, is to establish the principles governing the design, operation, and control of HRESs resulting in cost-effective and reliable energy solutions for stationary and mobile applications. To achieve this goal, we developed and demonstrated four separate HRES principles. Rational selection of HRES type: HRES components and their sizes should be rationally selected using knowledge of component costs, availability of renewable energy resources, and expected power demands of the application. HRES design: by default, the components of a HRES should be arranged in parallel for increased efficiency and reliability. However, a series HRES design may be preferred depending on the operational considerations of the HRES components. HRES control strategy selection: the choice of HRES control strategy depends on the dynamics of HRES components, their operational considerations, and the practical limitations of the HRES end-use. HRES data

  4. Stem cell self-renewal in intestinal crypt

    Energy Technology Data Exchange (ETDEWEB)

    Simons, Benjamin D., E-mail: bds10@cam.ac.uk [Cavendish Laboratory, Department of Physics, J.J. Thomson Avenue, University of Cambridge, Cambridge CB3 0HE (United Kingdom); The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN (United Kingdom); Clevers, Hans, E-mail: h.clevers@hubrecht.eu [Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht (Netherlands)

    2011-11-15

    As a rapidly cycling tissue capable of fast repair and regeneration, the intestinal epithelium has emerged as a favored model system to explore the principles of adult stem cell biology. However, until recently, the identity and characteristics of the stem cell population in both the small intestine and colon has remained the subject of debate. Recent studies based on targeted lineage tracing strategies, combined with the development of an organotypic culture system, have identified the crypt base columnar cell as the intestinal stem cell, and have unveiled the strategy by which the balance between proliferation and differentiation is maintained. These results show that intestinal stem cells operate in a dynamic environment in which frequent and stochastic stem cell loss is compensated by the proliferation of neighboring stem cells. We review the basis of these experimental findings and the insights they offer into the mechanisms of homeostatic stem cell regulation.

  5. Stem cell self-renewal in intestinal crypt

    International Nuclear Information System (INIS)

    As a rapidly cycling tissue capable of fast repair and regeneration, the intestinal epithelium has emerged as a favored model system to explore the principles of adult stem cell biology. However, until recently, the identity and characteristics of the stem cell population in both the small intestine and colon has remained the subject of debate. Recent studies based on targeted lineage tracing strategies, combined with the development of an organotypic culture system, have identified the crypt base columnar cell as the intestinal stem cell, and have unveiled the strategy by which the balance between proliferation and differentiation is maintained. These results show that intestinal stem cells operate in a dynamic environment in which frequent and stochastic stem cell loss is compensated by the proliferation of neighboring stem cells. We review the basis of these experimental findings and the insights they offer into the mechanisms of homeostatic stem cell regulation.

  6. Transition to 100% renewable energy systems in Denmark

    DEFF Research Database (Denmark)

    Meyer, Niels I; Hvelplund, Frede; Karnø, Peter;

    2012-01-01

    for reduction of greenhouse gas emissions have not been successful – in spite of supplementary problems in relation to “Peak Oil”. This paper presents the main results of a project analysing the solutions for a transition to 100 % renewable energy systems in Denmark before 2050 with focus on new and...... time horizons than the commercial market can offer. As a consequence, it is proposed that the balance between the commercial market and societal planning is shifted to the advantage of societal planning. It is an extra benefit from the proposed transition to a renewable energy system that it...... significantly improves the Danish energy supply security in relation to Peak Oil and the expected increasing oil price....

  7. Rethinking the Future Grid: Integrated Nuclear Renewable Energy Systems: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bragg-Sitton, S. M.; Boardman, R.; Ruth, M.; Zinaman, O.; Forsberg, C.

    2015-01-01

    The U.S. DOE is supporting research and development that could lead to more efficient utilization of clean energy generation sources, including renewable and nuclear options, to meet both grid demand and thermal energy needs in the industrial sector. One concept under consideration by the DOE-NE and DOE-EERE is tighter coupling of nuclear and renewable energy sources in a manner that better optimizes energy use for the combined electricity, industrial manufacturing, and transportation sectors. This integration concept has been referred to as a 'hybrid system' that is capable of apportioning thermal and electrical energy to first meet the grid demand (with appropriate power conversion systems), then utilizing excess thermal and, in some cases, electrical energy to drive a process that results in an additional product.

  8. Modeling and Implementation of Renewable Energy Sources to Distribution Systems

    Czech Academy of Sciences Publication Activity Database

    Tlustý, J.; Valouch, Viktor

    Santander: Universidad de Cantabria, 2008, s. 1-6. ISBN 978-84-611-9290-8. [International Conference on Renewable Energies and Power Quality - ICREPQ´08. Santander (ES), 12.03.2008-14.03.2008] R&D Projects: GA AV ČR IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : Power Quality Menagement System (POPQMS) * multi-machine dynamics * distribution network Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  9. Redispatching in an interconnected electricity system with high renewables penetration

    OpenAIRE

    Van den Bergh, Kenneth; Couckuyt, Dries; Delarue, Erik; D'Haeseleer, William

    2015-01-01

    Grid congestion management is gaining importance in certain parts of the European electricity grid. The deployment of renewable electricity sources at locations with a weak grid connection and far from the load centers can lead to overloading of transmission lines. Redispatching, i.e., rearranging scheduled generation and consumption, might be needed to obtain a feasible and safe operational state of the electricity system. This paper studies the impact of three parameters on the redispatchin...

  10. Final Progress Report, Renewable and Logistics Fuels for Fuel Cells at the Colorado School of Mines

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Neal P

    2012-08-06

    The objective of this program is to advance the current state of technology of solid-oxide fuel cells (SOFCs) to improve performance when operating on renewable and logistics hydrocarbon fuel streams. Outcomes will include: 1.) new SOFC materials and architectures that address the technical challenges associated with carbon-deposit formation and sulfur poisoning; 2.) new integration strategies for combining fuel reformers with SOFCs; 3.) advanced modeling tools that bridge the scales of fundamental charge-transfer chemistry to system operation and control; and 4.) outreach through creation of the Distinguished Lecturer Series to promote nationwide collaboration with fuel-cell researchers and scientists.

  11. Long-Term Self-Renewal of Postnatal Muscle-derived Stem Cells

    OpenAIRE

    Deasy, B. M.; Gharaibeh, B. M.; Pollett, J. B.; Jones, M.M.; Lucas, M. A.; Kanda, Y.; Huard, J

    2005-01-01

    The ability to undergo self-renewal is a defining characteristic of stem cells. Self-replenishing activity sustains tissue homeostasis and regeneration. In addition, stem cell therapy strategies require a heightened understanding of the basis of the self-renewal process to enable researchers and clinicians to obtain sufficient numbers of undifferentiated stem cells for cell and gene therapy. Here, we used postnatal muscle-derived stem cells to test the basic biological assumption of unlimited...

  12. Stem cell signaling. An integral program for tissue renewal and regeneration : Wnt signaling and stem cell control

    NARCIS (Netherlands)

    Clevers, Hans; Loh, Kyle M; Nusse, Roel

    2014-01-01

    Stem cells fuel tissue development, renewal, and regeneration, and these activities are controlled by the local stem cell microenvironment, the "niche." Wnt signals emanating from the niche can act as self-renewal factors for stem cells in multiple mammalian tissues. Wnt proteins are lipid-modified,

  13. Fibroblast growth factors as regulators of stem cell self-renewal and aging

    NARCIS (Netherlands)

    Yeoh, Joyce S. G.; de Haan, Gerald

    2007-01-01

    Organ and tissue dysfunction which is readily observable during aging results from a loss of cellular homeostasis and reduced stem cell self-renewal. Over the past 10 years, studies have been aimed at delineating growth factors that will sustain and promote the self-renewal potential of stem cells a

  14. Power electronics - key technology for renewable energy systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Iov, Florin; Kerekes, Tamas;

    2011-01-01

    as efficient as possible. Further, the emerging climate changes is arguing to find sustainable future solutions. Of many options, two major technologies will play important roles to solve parts of those future problems. One is to change the electrical power production from conventional, fossil based energy...... sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which by means of power electronics...... are changing and challenging the future electrical infrastructure but also contributes steadily more to non-carbon based electricity production. Most focus in the paper is on the power electronics technologies used. In the case of photovoltaics transformer-less systems are discussed as they have the potential...

  15. Trends in Power Electronics and Control of Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Iov, Florin; Kerekes, Tamas;

    2010-01-01

    are done as efficient as possible. Further, emerging climate changes argues to find future solutions which also are sustainable. Two major technologies will play important roles to solve parts of those future problems. One is the change the electrical power production from conventional, fossil (and short...... term) based energy sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which...... by means of power electronics are changing the future electrical infrastructure but also contributes steadily more to non-carbon based electricity production. Most focus is on the power electronics technologies used. In the case of photovoltaics transformer-less systems are discussed as they have...

  16. Renewable energy systems the earthscan expert guide to renewable energy technologies for home and business

    CERN Document Server

    Jenkins, Dilwyn

    2013-01-01

    This book is the long awaited guide for anyone interested in renewables at home or work. It sweeps away scores of common misconceptions while clearly illustrating the best in renewable and energy efficiency technologies. A fully illustrated guide to renewable energy for the home and small business, the book provides an expert overview of precisely which sustainable energy technologies are appropriate for wide-spread domestic and small business application. The sections on different renewable energy options provide detailed descriptions of each technology along with case studies, installatio

  17. The New Role of Renewable Energy Systems In Developing GCC Electricity Market

    Directory of Open Access Journals (Sweden)

    Amir J. Majid

    2011-04-01

    Full Text Available Due to the present high oil prices, prices fluctuations and their future upwardtrend, some investments can be now directed to the utilization of solar and otherrenewable energy systems, such as hydrogen cells and cyclic hydro systems. Itis believed that the infrastructure of these systems is particularly feasiblethrough the already large constructions and investments in real estate industrythroughout GCC countries. It is also feasible in rural areas such as farms andsmall villages due to the relatively low power demand and load characteristics.This can also lead to the disintegration, liberalization and privatization of energysystems. The electric energy and power disintegration of such smallcorporations would save resources, reduce interactions and increase reliability.This paper focuses on suggested new regulations needed to control theutilization of renewable energy systems in rural areas in order to make benefit ofhigh oil prices. It also focuses on the category and types of renewable energysystems that can be implemented in this project.

  18. Modelization of a hybrid system with renewable energy for electric propulsion in boats. Application to a robotic floating platform

    OpenAIRE

    Jiménez Ariza, J.M.; Gómez Lopera, S.A.

    2015-01-01

    A model of a hybrid system with renewable energy for electric propulsion in boats in which energy generated by photovoltaic panels and hydrogenerator is stored in the main battery which exerts its function as central element of a renewable cycle is presented. Additionally, hydrogen plays a role being generated by an electrolyzer for later to be stored in cylinders aboard in order to generate electric power by a fuel cell. Both, batteries and cylinders can be used to feed the di...

  19. Control analysis of renewable energy system with hydrogen storage for residential applications

    Energy Technology Data Exchange (ETDEWEB)

    Bilodeau, A.; Agbossou, K. [Hydrogen Research Institute, Universite du Quebec a Trois-Rivieres, 3351 boul. Des Forges, C.P. 500, Trois-Rivieres, Que. (Canada G9A 5H7)

    2006-11-22

    The combination of an electrolyzer and a fuel cell can provide peak power control in a decentralized/distributed power system. The electrolyzer produces hydrogen and oxygen from off-peak electricity generated by the renewable energy sources (wind turbine and photovoltaic array), for later use in the fuel cell to produce on-peak electricity. An issue related to this system is the control of the hydrogen loop (electrolyzer, tank, fuel cell). A number of control algorithms were developed to decide when to produce hydrogen and when to convert it back to electricity, most of them assuming that the electrolyzer and the fuel cell run alternatively to provide nominal power (full power). This paper presents a complete model of a stand-alone renewable energy system with hydrogen storage controlled by a dynamic fuzzy logic controller (FLC). In this system, batteries are used as energy buffers and for short time storage. To study the behavior of such a system, a complete model is developed by integrating the individual sub-models of the fuel cell, the electrolyzer, the power conditioning units, the hydrogen storage system, and the batteries. An analysis of the performances of the dynamic fuzzy logic controller is then presented. This model is useful for building efficient peak power control. (author)

  20. Iris-based authentication system with template protection and renewability

    Science.gov (United States)

    Ercole, Chiara; Campisi, Patrizio; Neri, Alessandro

    2007-10-01

    Biometrics is the most emerging technology for automatic people authentication, nevertheless severe concerns raised about security of such systems and users' privacy. In case of malicious attacks toward one or more components of the authentication system, stolen biometric features cannot be replaced. This paper focuses on securing the enrollment database and the communication channel between such database and the matcher. In particular, a method is developed to protect the stored biometric templates, adapting the fuzzy commitment scheme to iris biometrics by exploiting error correction codes tailored on template discriminability. The aforementioned method allows template renewability applied to iris based authentication and guarantees high security performing the match in the encrypted domain.

  1. Stem cell self-renewal in intestinal crypt

    NARCIS (Netherlands)

    Simons, B.D.; Clevers, H.

    2011-01-01

    As a rapidly cycling tissue capable of fast repair and regeneration, the intestinal epithelium has emerged as a favored model system to explore the principles of adult stem cell biology. However, until recently, the identity and characteristics of the stem cell population in both the small intestine

  2. Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

    DEFF Research Database (Denmark)

    Nielsen, L.H.; Jørgensen K.

    2000-01-01

    vehicles. Focus is put on the Danish fleet of passenger cars and delivery vans. The scenario analysisincludes assumptions on market potential developments and market penetration for the alternative vehicles. Vehicle replacement rates in the Danish transport fleet and the size of fleet development are based...... on data from The Danish Road Directorate. Theelectricity supply system development assumed is based on the Danish energy plan, Energy 21, The Plan scenario. The time horizon of the analysis is year 2030. Results from the scenario analysis include the time scales involved for the potentialtransition...... towards electricity based vehicles, the fleet composition development, the associated developments in transport fuel consumption and fuel substitution, and the potential CO2-emission reduction achievable in the overall transport and powersupply system. Detailed model simulations, on an hourly basis, have...

  3. Spermatogonial stem cell renewal in the mouse as revealed by 3H-thymidine labeling and irradiation

    International Nuclear Information System (INIS)

    Procedures are described for sectioning and staining mouse testes, x-irradiation of mice, and classification of developing sperm cells. Tables are presented to show frequency of labeled cells following exposure to various doses of x radiation. A discussion is presented of types of spermatogonia surviving various radiation doses and times of incorporation of 3H-TdR in the cycle of the seminiferous epithelium. Models of stem cell renewal systems are described

  4. Endothelial cell-initiated signaling promotes the survival and self-renewal of cancer stem cells

    Science.gov (United States)

    Krishnamurthy, Sudha; Dong, Zhihong; Vodopyanov, Dmitry; Imai, Atsushi; Helman, Joseph I.; Prince, Mark E.; Wicha, Max S.; Nör, Jacques E.

    2010-01-01

    Recent studies have demonstrated that cancer stem cells play an important role in the pathobiology of head and neck squamous cell carcinomas (HNSCC). However, little is known about functional interactions between head and neck cancer stem-like cells (CSC) and surrounding stromal cells. Here, we used Aldehyde Dehydrogenase activity and CD44 expression to sort putative stem cells from primary human HNSCC. Implantation of 1,000 CSC (ALDH+CD44+Lin−) led to tumors in 13 (out of 15) mice, while 10,000 non-cancer stem cells (NCSC; ALDH−CD44−Lin−) resulted in 2 tumors in 15 mice. These data demonstrated that ALDH and CD44 select a sub-population of cells that are highly tumorigenic. The ability to self-renew was confirmed by the observation that ALDH+CD44+Lin− cells sorted from human HNSCC formed more spheroids (orospheres) in 3-D agarose matrices or ultra-low attachment plates than controls and were serially passaged in vivo. We observed that approximately 80% of the CSC were located in close proximity (within 100-µm radius) of blood vessels in human tumors, suggesting the existence of perivascular niches in HNSCC. In vitro studies demonstrated that endothelial cell-secreted factors promoted self-renewal of CSC, as demonstrated by the upregulation of Bmi-1 expression and the increase in the number of orospheres as compared to controls. Notably, selective ablation of tumor-associated endothelial cells stably transduced with a caspase-based artificial death switch (iCaspase-9) caused a marked reduction in the fraction of CSC in xenograft tumors. Collectively, these findings indicate that endothelial cell-initiated signaling can enhance the survival and self-renewal of head and neck cancer stem cells. PMID:21098716

  5. RETHINKING THE FUTURE GRID: INTEGRATED NUCLEAR-RENEWABLE ENERGY SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    S.M. Bragg-Sitton; R. Boardman

    2014-12-01

    The 2013 electricity generation mix in the United States consisted of ~13% renewables (hydropower, wind, solar, geothermal), 19% nuclear, 27% natural gas, and 39% coal. In the 2011 State of the Union Address, President Obama set a clean energy goal for the nation: “By 2035, 80 percent of America’s electricity will come from clean energy sources. Some folks want wind and solar. Others want nuclear, clean coal and natural gas. To meet this goal we will need them all.” The U.S. Department of Energy (DOE) Offices of Nuclear Energy (NE) and Energy Efficiency and Renewable Energy (EERE) recognize that “all of the above” means that we are called to best utilize all available clean energy sources. To meet the stated environmental goals for electricity generation and for the broader energy sector, there is a need to transform the energy infrastructure of the U.S. and elsewhere. New energy systems must be capable of significantly reducing environmental impacts in an efficient and economically viable manner while utilizing both hydrocarbon resources and clean energy generation sources. The U.S. DOE is supporting research and development that could lead to more efficient utilization of clean energy generation sources, including renewable and nuclear options, to meet both grid demand and thermal energy needs in the industrial sector. A concept being advanced by the DOE-NE and DOE-EERE is tighter coupling of nuclear and renewable energy sources in a manner that better optimizes energy use for the combined electricity, industrial manufacturing, and the transportation sectors. This integration concept has been referred to as a “hybrid system” that is capable of apportioning thermal and electrical energy to first meet the grid demand (with appropriate power conversion systems), then utilizing excess thermal and, in some cases, electrical energy to drive a process that results in an additional product. For the purposes of the present work, the hybrid system would

  6. Transient inhibition of cell proliferation does not compromise self-renewal of mouse embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruoxing [Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive 5018, Hattiesburg, MS 39406 (United States); Guo, Yan-Lin, E-mail: yanlin.guo@usm.edu [Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive 5018, Hattiesburg, MS 39406 (United States)

    2012-10-01

    Embryonic stem cells (ESCs) have unlimited capacity for self-renewal and can differentiate into various cell types when induced. They also have an unusual cell cycle control mechanism driven by constitutively active cyclin dependent kinases (Cdks). In mouse ESCs (mESCs). It is proposed that the rapid cell proliferation could be a necessary part of mechanisms that maintain mESC self-renewal and pluripotency, but this hypothesis is not in line with the finding in human ESCs (hESCs) that the length of the cell cycle is similar to differentiated cells. Therefore, whether rapid cell proliferation is essential for the maintenance of mESC state remains unclear. We provide insight into this uncertainty through chemical intervention of mESC cell cycle. We report here that inhibition of Cdks with olomoucine II can dramatically slow down cell proliferation of mESCs with concurrent down-regulation of cyclin A, B and E, and the activation of the Rb pathway. However, mESCs display can recover upon the removal of olomoucine II and are able to resume normal cell proliferation without losing self-renewal and pluripotency, as demonstrated by the expression of ESC markers, colony formation, embryoid body formation, and induced differentiation. We provide a mechanistic explanation for these observations by demonstrating that Oct4 and Nanog, two major transcription factors that play critical roles in the maintenance of ESC properties, are up-regulated via de novo protein synthesis when the cells are exposed to olomoucine II. Together, our data suggest that short-term inhibition of cell proliferation does not compromise the basic properties of mESCs. -- Highlights: Black-Right-Pointing-Pointer Inhibition of Cdks slows down mESCs proliferation. Black-Right-Pointing-Pointer mESCs display remarkable recovery capacity from short-term cell cycle interruption. Black-Right-Pointing-Pointer Short-term cell cycle interruption does not compromise mESC self-renewal. Black

  7. Transient inhibition of cell proliferation does not compromise self-renewal of mouse embryonic stem cells

    International Nuclear Information System (INIS)

    Embryonic stem cells (ESCs) have unlimited capacity for self-renewal and can differentiate into various cell types when induced. They also have an unusual cell cycle control mechanism driven by constitutively active cyclin dependent kinases (Cdks). In mouse ESCs (mESCs). It is proposed that the rapid cell proliferation could be a necessary part of mechanisms that maintain mESC self-renewal and pluripotency, but this hypothesis is not in line with the finding in human ESCs (hESCs) that the length of the cell cycle is similar to differentiated cells. Therefore, whether rapid cell proliferation is essential for the maintenance of mESC state remains unclear. We provide insight into this uncertainty through chemical intervention of mESC cell cycle. We report here that inhibition of Cdks with olomoucine II can dramatically slow down cell proliferation of mESCs with concurrent down-regulation of cyclin A, B and E, and the activation of the Rb pathway. However, mESCs display can recover upon the removal of olomoucine II and are able to resume normal cell proliferation without losing self-renewal and pluripotency, as demonstrated by the expression of ESC markers, colony formation, embryoid body formation, and induced differentiation. We provide a mechanistic explanation for these observations by demonstrating that Oct4 and Nanog, two major transcription factors that play critical roles in the maintenance of ESC properties, are up-regulated via de novo protein synthesis when the cells are exposed to olomoucine II. Together, our data suggest that short-term inhibition of cell proliferation does not compromise the basic properties of mESCs. -- Highlights: ► Inhibition of Cdks slows down mESCs proliferation. ► mESCs display remarkable recovery capacity from short-term cell cycle interruption. ► Short-term cell cycle interruption does not compromise mESC self-renewal. ► Oct4 and Nanog are up-regulated via de novo synthesis by cell cycle interruption.

  8. Modeling of an Integrated Renewable Energy System (IRES) with hydrogen storage

    Science.gov (United States)

    Shenoy, Navin Kodange

    2010-12-01

    Scope and Method of Study. The purpose of the study was to consider the integration of hydrogen storage technology as means of energy storage with renewable sources of energy. Hydrogen storage technology consists of an alkaline electrolyzer, gas storage tank and a fuel cell. The Integrated Renewable Energy System (IRES) under consideration includes wind energy, solar energy from photovoltaics, solar thermal energy and biomass energy in the form of biogas. Energy needs are categorized depending on the type and quality of the energy requirements. After meeting all the energy needs, any excess energy available from wind and PVs is converted into hydrogen using an electrolyzer for later use in a fuel cell. Similarly, when renewable energy generation is not able to supply the actual load demand, the stored hydrogen is utilized through fuel cell to fulfill load demand. Analysis of how IRES operates in order to satisfy different types of energy needs is discussed. Findings and Conclusions. All simulations are performed using MATLAB software. Hydrogen storage technology consisting of an electrolyzer, gas storage tank and a fuel cell is incorporated in the IRES design process for a hypothetical remote community. Results show that whenever renewable energy generated is greater than the electrical demand, excess energy is stored in the form of hydrogen and in case of energy shortfall, the stored hydrogen is utilized through the fuel cell to supply to excess power demand. The overall operation of IRES is enhanced as a result of energy storage in the form of hydrogen. Hydrogen has immense potential to be the energy carrier of the future because of its clean character and the model of hydrogen storage discussed here can form an integral part of IRES for remote area applications.

  9. Renewable Energy Systems in the Power Electronics Curriculum

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

    2005-01-01

    of the most important area is renewable energy systems. This paper will discuss the basic courses for the power electronics curriculum. It will also discuss how to teach power electronic systems efficiently through a projectoriented and problem-based learning approach with Aalborg University in Denmark......Power Electronics is still an emerging technology and its applications are increasing. The primary function is to convert electrical energy from one stage to another and it is used in many different applications. The power electronics curriculum is multidisciplinary covering fields like devices......, magnetics, electrical machines, power systems, analogue and digital control, materials, power converters, electronics, materials, thermal design and EMC. However, those fields may not be enough in order to give the students enough skills. It is also necessary to learn about systems and for the moment one...

  10. Interregional technology transfer on advanced materials and renewable energy systems

    International Nuclear Information System (INIS)

    Advanced materials are used in most industrial sectors and human activities and all developing and developed countries as well as international organizations eg. United Nations have established work groups, which survey the national and global state and developments in the area of advanced materials trying to establish strategies on that crucial technology sector. These strategies are focused on research and technology activities including education and vocation training, as well as stimulus for the starting up of new industrial applications. To introduce such a concept in Greece and especially in Northern Greece, the Technological Education Institute of Serres has initiated an Interregional technology transfer project in this scientific field. This project includes mod topics of advanced materials technology with emphasison specific industrial applications (renewable energy systems). The project demonstrates the development of a prototype photovoltaic thermal system in terms of a new industrial product. The product development procedure consists of steps such as initial product design, materials selection and processing, prototype design and manufacturing, quality control, performance optimization, but also control of materials ecocompatibility according to the national trends of life cycle design and recycling techniques. Keywords: Interregional technology transfer, materials, renewable energy systems

  11. Energy Storage Applications in Power Systems with Renewable Energy Generation

    Science.gov (United States)

    Ghofrani, Mahmoud

    In this dissertation, we propose new operational and planning methodologies for power systems with renewable energy sources. A probabilistic optimal power flow (POPF) is developed to model wind power variations and evaluate the power system operation with intermittent renewable energy generation. The methodology is used to calculate the operating and ramping reserves that are required to compensate for power system uncertainties. Distributed wind generation is introduced as an operational scheme to take advantage of the spatial diversity of renewable energy resources and reduce wind power fluctuations using low or uncorrelated wind farms. The POPF is demonstrated using the IEEE 24-bus system where the proposed operational scheme reduces the operating and ramping reserve requirements and operation and congestion cost of the system as compared to operational practices available in the literature. A stochastic operational-planning framework is also proposed to adequately size, optimally place and schedule storage units within power systems with high wind penetrations. The method is used for different applications of energy storage systems for renewable energy integration. These applications include market-based opportunities such as renewable energy time-shift, renewable capacity firming, and transmission and distribution upgrade deferral in the form of revenue or reduced cost and storage-related societal benefits such as integration of more renewables, reduced emissions and improved utilization of grid assets. A power-pool model which incorporates the one-sided auction market into POPF is developed. The model considers storage units as market participants submitting hourly price bids in the form of marginal costs. This provides an accurate market-clearing process as compared to the 'price-taker' analysis available in the literature where the effects of large-scale storage units on the market-clearing prices are neglected. Different case studies are provided to

  12. Tissue-resident adult stem cell populations of rapidly self-renewing organs

    NARCIS (Netherlands)

    Barker, N.; Bartfeld, S.; Clevers, H.

    2010-01-01

    The epithelial lining of the intestine, stomach, and skin is continuously exposed to environmental assault, imposing a requirement for regular self-renewal. Resident adult stem cell populations drive this renewal, and much effort has been invested in revealing their identity. Reliable adult stem cel

  13. Myostatin signals through Pax7 to regulate satellite cell self-renewal

    International Nuclear Information System (INIS)

    Myostatin, a Transforming Growth Factor-beta (TGF-β) super-family member, has previously been shown to negatively regulate satellite cell activation and self-renewal. However, to date the mechanism behind Myostatin function in satellite cell biology is not known. Here we show that Myostatin signals via a Pax7-dependent mechanism to regulate satellite cell self-renewal. While excess Myostatin inhibited Pax7 expression via ERK1/2 signaling, an increase in Pax7 expression was observed following both genetic inactivation and functional antagonism of Myostatin. As a result, we show that either blocking or inactivating Myostatin enhances the partitioning of the fusion-incompetent self-renewed satellite cell lineage (high Pax7 expression, low MyoD expression) from the pool of actively proliferating myogenic precursor cells. Consistent with this result, over-expression of Pax7 in C2C12 myogenic cells resulted in increased self-renewal through a mechanism which slowed both myogenic proliferation and differentiation. Taken together, these results suggest that increased expression of Pax7 promotes satellite cell self-renewal, and furthermore Myostatin may control the process of satellite cell self-renewal through regulation of Pax7. Thus we speculate that, in addition to the intrinsic factors (such as Pax7), extrinsic factors both positive and negative in nature, will play a major role in determining the stemness of skeletal muscle satellite cells

  14. DC Distributed Power Systems - Analysis, Design and Control for a Renewable Energy System

    OpenAIRE

    Karlsson, Per

    2002-01-01

    Renewable energy systems are likely to become wide spread in the future due to environmental demands. As a consequence of the dispersed nature of renewable energy systems, this implies that there will be a distributed generation of electric power. Since most of the distributed electrical energy sources do not provide their electric power at line frequency and voltage, a DC bus is a useful common connection for several such sources. Due to the differences in output voltage among the sources, d...

  15. Renewable energy resources in Pakistan: status, potential and information systems

    International Nuclear Information System (INIS)

    This paper provides some details regarding the characteristic properties, potential and assessment of renewable energy compared with other forms of energy sources. It gives status of renewable energy sources in Pakistan. It also lights about the agencies providing technical information regarding renewable energy in Pakistan as well as suggestions and recommendations for the development of these resources, and over view the present status of renewable energy sources. (author)

  16. Proceedings of World Renewable Energy Congress '99

    International Nuclear Information System (INIS)

    The congress discussed the following subjects, 1. The role of renewable energy in the next millenium; 2. Challenges in the commercialization of renewable energy; 3. The role and agenda for renewable energy towards sustainable development. Topics covered in the technical session were biomass conversion; solar thermal technologies and systems; solar photovoltaic s; renewable energy economics, financing and policy; renewable energy education; climate and the environment; energy and architecture; energy management; wind and hydro technologies and systems; hydrogen and fuel cell

  17. Power System Study for Renewable Energy Interconnection in Malaysia

    International Nuclear Information System (INIS)

    The renewable energy (RE) sector has grown exponentially in Malaysia with the introduction of the Feed-In-Tariff (FIT) by the Ministry of Energy, Green Technology and Water. Photovoltaic, biogas, biomass and mini hydro are among the renewable energy sources which offer a lucrative tariff to incite developers in taking the green technology route. In order to receive the FIT, a developer is required by the utility company to perform a power system analysis which will determine the technical feasibility of an RE interconnection to the utility company's existing grid system. There are a number of aspects which the analysis looks at, the most important being the load flow and fault levels in the network after the introduction of an RE source. The analysis is done by modelling the utility company's existing network and simulating the network with the interconnection of an RE source. The results are then compared to the values before an interconnection is made as well as ensuring the voltage rise or the increase in fault levels do not violate any pre-existing regulations set by the utility company. This paper will delve into the mechanics of performing a load flow analysis and examining the results obtained.

  18. Power System Study for Renewable Energy Interconnection in Malaysia

    Science.gov (United States)

    Askar, O. F.; Ramachandaramurthy, V. K.

    2013-06-01

    The renewable energy (RE) sector has grown exponentially in Malaysia with the introduction of the Feed-In-Tariff (FIT) by the Ministry of Energy, Green Technology and Water. Photovoltaic, biogas, biomass and mini hydro are among the renewable energy sources which offer a lucrative tariff to incite developers in taking the green technology route. In order to receive the FIT, a developer is required by the utility company to perform a power system analysis which will determine the technical feasibility of an RE interconnection to the utility company's existing grid system. There are a number of aspects which the analysis looks at, the most important being the load flow and fault levels in the network after the introduction of an RE source. The analysis is done by modelling the utility company's existing network and simulating the network with the interconnection of an RE source. The results are then compared to the values before an interconnection is made as well as ensuring the voltage rise or the increase in fault levels do not violate any pre-existing regulations set by the utility company. This paper will delve into the mechanics of performing a load flow analysis and examining the results obtained.

  19. Power quality analysis of hybrid renewable energy system

    Directory of Open Access Journals (Sweden)

    Rinchin W. Mosobi

    2015-12-01

    Full Text Available An hybrid renewable energy sources consisting of solar photovoltaic, wind energy system, and a microhydro system is proposed in this paper. This system is suitable for supplying electricity to isolated locations or remote villages far from the grid supply. The solar photovoltaic system is modeled with two power converters, the first one being a DC-DC converter along with an maximum power point tracking to achieve a regulated DC output voltage and the second one being a DC-AC converter to obtain AC output. The wind energy system is modeled with a wind-turbine prime mover with varying wind speed and fixed pitch angle to drive an self excited induction generator (SEIG. Owing to inherent drooping characteristics of the SEIG, a closed loop turbine input system is incorporated. The microhydro system is modeled with a constant input power to drive an SEIG. The three different sources are integrated through an AC bus and the proposed hybrid system is supplied to R, R-L, and induction motor loads. A static compensator is proposed to improve the load voltage and current profiles; it also mitigates the harmonic contents of the voltage and current. The static synchronous compensator is realized by means of a three-phase IGBT-based current-controlled voltage source inverter with a self-supporting DC bus. The complete system is modeled and simulated using Matlab/Simulink. The simulation results obtained illustrate the feasibility of the proposed system and are found to be satisfactory.

  20. Is there dependence and systemic risk between oil and renewable energy stock prices?

    International Nuclear Information System (INIS)

    We study systemic risk and dependence between oil and renewable energy markets using copulas to characterize the dependence structure and to compute the conditional value-at-risk as a measure of systemic risk. We found significant time-varying average and symmetric tail dependence between oil returns and several global and sectoral renewable energy indices. Our evidence on systemic risk indicates that oil price dynamics significantly contributes around 30% to downside and upside risk of renewable energy companies. These results have important implications for risk management and renewable energy policies. - Highlights: • We study systemic risk and dependence between oil and renewable energy markets. • Dependence and conditional value-at-risk is obtained through copulas. • Oil and renewable energy displayed time-varying average and symmetric tail dependence. • Oil price contribution to the downside and upside risks of renewable energy companies was around 30%

  1. Medium Renewal Blocks Anti-Proliferative Effects of Metformin in Cultured MDA-MB-231 Breast Cancer Cells.

    Directory of Open Access Journals (Sweden)

    Maruša Rajh

    Full Text Available Epidemiological studies indicate that metformin, a widely used type 2 diabetes drug, might reduce breast cancer risk and mortality in patients with type 2 diabetes. Metformin might protect against breast cancer indirectly by ameliorating systemic glucose homeostasis. Alternatively, it might target breast cancer cells directly. However, experiments using MDA-MB-231 cells, a standard in vitro breast cancer model, produced inconsistent results regarding effectiveness of metformin as a direct anti-cancer agent. Metformin treatments in cultured MDA-MB-231 cells are usually performed for 48-96 hours, but protocols describing renewal of cell culture medium during these prolonged treatments are rarely reported. We determined whether medium renewal protocol might alter sensitivity of MDA-MB-231 cells treated with metformin. Using the MTS assay, BrdU incorporation and Hoechst staining we found that treatment with metformin for 48-72 hours failed to suppress viability and proliferation of MDA-MB-231 cells if low-glucose (1 g/L medium was renewed every 24 hours. Conversely, metformin suppressed their viability and proliferation if medium was not renewed. Without renewal glucose concentration in the medium was reduced to 0.1 g/L in 72 hours, which likely explains increased sensitivity to metformin under these conditions. We also examined whether 2-deoxy-D-glucose (2-DG reduces resistance to metformin. In the presence of 2-DG metformin reduced viability and proliferation of MDA-MB-231 cells with or without medium renewal, thus demonstrating that 2-DG reduces their resistance to metformin. In sum, we show that medium renewal blocks anti-proliferative effects of metformin during prolonged treatments in low-glucose medium. Differences in medium renewal protocols during prolonged treatments might therefore lead to apparently inconsistent results as regards effectiveness of metformin as a direct anti-cancer agent. Finally, our results indicate that co-therapy with

  2. Medium Renewal Blocks Anti-Proliferative Effects of Metformin in Cultured MDA-MB-231 Breast Cancer Cells.

    Science.gov (United States)

    Rajh, Maruša; Dolinar, Klemen; Miš, Katarina; Pavlin, Mojca; Pirkmajer, Sergej

    2016-01-01

    Epidemiological studies indicate that metformin, a widely used type 2 diabetes drug, might reduce breast cancer risk and mortality in patients with type 2 diabetes. Metformin might protect against breast cancer indirectly by ameliorating systemic glucose homeostasis. Alternatively, it might target breast cancer cells directly. However, experiments using MDA-MB-231 cells, a standard in vitro breast cancer model, produced inconsistent results regarding effectiveness of metformin as a direct anti-cancer agent. Metformin treatments in cultured MDA-MB-231 cells are usually performed for 48-96 hours, but protocols describing renewal of cell culture medium during these prolonged treatments are rarely reported. We determined whether medium renewal protocol might alter sensitivity of MDA-MB-231 cells treated with metformin. Using the MTS assay, BrdU incorporation and Hoechst staining we found that treatment with metformin for 48-72 hours failed to suppress viability and proliferation of MDA-MB-231 cells if low-glucose (1 g/L) medium was renewed every 24 hours. Conversely, metformin suppressed their viability and proliferation if medium was not renewed. Without renewal glucose concentration in the medium was reduced to 0.1 g/L in 72 hours, which likely explains increased sensitivity to metformin under these conditions. We also examined whether 2-deoxy-D-glucose (2-DG) reduces resistance to metformin. In the presence of 2-DG metformin reduced viability and proliferation of MDA-MB-231 cells with or without medium renewal, thus demonstrating that 2-DG reduces their resistance to metformin. In sum, we show that medium renewal blocks anti-proliferative effects of metformin during prolonged treatments in low-glucose medium. Differences in medium renewal protocols during prolonged treatments might therefore lead to apparently inconsistent results as regards effectiveness of metformin as a direct anti-cancer agent. Finally, our results indicate that co-therapy with 2-DG and

  3. Stochastic Modeling and Analysis of Power System with Renewable Generation

    DEFF Research Database (Denmark)

    Chen, Peiyuan

    evaluation can be achieved through a probabilistic analysis that takes into account the stochastic behavior of wind power generation (WPG) and load demand. Such a probabilistic analysis may help network operators to cut down the cost associated with system planning. Thus, the objective of this thesis is to...... control and energy curtailment of WTs, subject to voltage and current constraints. These developed models and proposed algorithms serve as effective tools to assist network operators in decision-making during the operation and planning of power systems.......Unlike traditional fossil-fuel based power generation, renewable generation such as wind power relies on uncontrollable prime sources such as wind speed. Wind speed varies stochastically, which to a large extent determines the stochastic behavior of power generation from wind farms. With the...

  4. Optimizing the U.S. Electric System with a High Penetration of Renewables

    Science.gov (United States)

    Corcoran, B. A.; Jacobson, M. Z.

    2013-12-01

    As renewable energy generators are increasingly being installed throughout the U.S., there is growing interest in interconnecting diverse renewable generators (primarily wind and solar) across large geographic areas through an enhanced transmission system. This reduces variability in the aggregate power output, increases system reliability, and allows for the development of the best overall group of renewable technologies and sites to meet the load. Studies are therefore needed to determine the most efficient and economical plan to achieve large area interconnections in a future electric system with a high penetration of renewables. This research quantifies the effects of aggregating electric load together with diverse renewable generation throughout the ten Federal Energy Regulatory Commission (FERC) regions in the contiguous U.S. A deterministic linear program has been built in AMPL (A Mathematical Programming Language) to solve for the least-cost organizational structure and system (generators, transmission, and storage) for a highly renewable electric grid. The analysis will 1) examine a highly renewable 2006 electric system, including various sensitivity cases and additional system components such as additional load from electric vehicles, and 2) create a 'roadmap' from the existing 2006 system to a highly renewable system in 2030, accounting for projected price and demand changes and generator retirements based on age and environmental regulations. Ideally, results from this study will offer insight for a federal renewable energy policy (such as a renewable portfolio standard) and how to best organize U.S. regions for transmission planning.

  5. Power Electronics and Control of Renewable Energy Systems

    DEFF Research Database (Denmark)

    Iov, Florin; Ciobotaru, Mihai; Sera, Dezso;

    2007-01-01

    The global electrical energy consumption is still rising and there is a demand to double the power capacity within 20 years. The production, distribution and use of energy should be as technological efficient as possible and incentives to save energy at the end-user should also be set up. Deregul......, wind energy and photovoltaics, which by means of power electronics are changing from being minor energy sources to be acting as important power sources in the energy system........ Deregulation of energy has in the past lowered the investment in larger power plants, which means the need for new electrical power sources may be very high in the near future. Two major technologies will play important roles to solve the future problems. One is to change the electrical power production...... sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources...

  6. Markov Renewal Methods in Restart Problems in Complex Systems

    DEFF Research Database (Denmark)

    Asmussen, Søren; Lipsky, Lester; Thompson, Stephen

    general alternating Markov renewal model is proposed and an asymptotic exponential form P(X > x) ∼ Ce−γx identified for the case of a deterministic task time L ≡ `. The rate γ is given by equating the spectral radius of a certain matrix to 1, and the asymptotic form of γ = γ(`) as ` → ∞ is derived......A task with ideal execution time L such as the execution of a computer program or the transmission of a file on a data link may fail, and the task then needs to be restarted. The task is handled by a complex system with features similar to the ones in classical reliability: failures may be......, leading to the asymptotics of P(X > x) for random task times L. A main finding is that X is always heavy-tailed if L has unbounded support. The case where the Markov renewal model is derived by lumping in a continuous-time finite Markov process with exponential holding times is given special attention...

  7. Lead-acid battery use in the development of renewable energy systems in China

    International Nuclear Information System (INIS)

    Policies and laws encouraging the development of renewable energy systems in China have led to rapid progress in the past 2 years, particularly in the solar cell (photovoltaic) industry. The development of the photovoltaic (PV) and wind power markets in China is outlined in this paper, with emphasis on the utilization of lead-acid batteries. The storage battery is a key component of PV/wind power systems, yet many deficiencies remain to be resolved. Some experimental results are presented, along with examples of potential applications of valve regulated lead-acid (VRLA) batteries, both the absorbed glass mat (AGM) and gelled types. (author)

  8. Lead-acid battery use in the development of renewable energy systems in China

    Science.gov (United States)

    Chang, Yu; Mao, Xianxian; Zhao, Yanfang; Feng, Shaoli; Chen, Hongyu; Finlow, David

    Policies and laws encouraging the development of renewable energy systems in China have led to rapid progress in the past 2 years, particularly in the solar cell (photovoltaic) industry. The development of the photovoltaic (PV) and wind power markets in China is outlined in this paper, with emphasis on the utilization of lead-acid batteries. The storage battery is a key component of PV/wind power systems, yet many deficiencies remain to be resolved. Some experimental results are presented, along with examples of potential applications of valve regulated lead-acid (VRLA) batteries, both the absorbed glass mat (AGM) and gelled types.

  9. Design of a mediated enzymatic fuel cell to generate power from renewable fuel sources.

    Science.gov (United States)

    Korkut, Seyda; Kilic, Muhammet Samet

    2016-01-01

    The present work reported a compartment-less enzymatic fuel cell (EFC) based on newly synthesized Poly(pyrrole-2-carboxylic acid-co-3-thiophene acetic acid) film containing glucose oxidase and laccase effectively wired by p-benzoquinone incorporated into the copolymer structure. The resulting system generated a power density of 18.8 µW/cm(2) with 30 mM of glucose addition at +0.94 V at room temperature. Improvements to maximize the power output were ensured with step-by-step optimization of electrode fabrication design and operational parameters for operating the system with renewable fuel sources. We demonstrated that the improved fuel cell could easily harvest glucose produced during photosynthesis to produce electrical energy in a simple, renewable and sustainable way by generating a power density of 10 nW/cm(2) in the plant leaf within 2 min. An EFC for the first time was successfully operated in municipal wastewater which contained glycolytic substances to generate electrical energy with a power output of 3.3 µW/cm(2). PMID:26102352

  10. Solar-Hydrogen-Fuel Cell Prototype as a Source of Renewable Energy Generation

    OpenAIRE

    Andrés Rodríguez-Castellanos; Ernesto López-Torres; Omar Solorza-Feria

    2007-01-01

    A small renewable energy prototype is presented, integrated by a solar photovoltaic module used for electrolysis of water where the resulting hydrogen was fed to a regenerative fuel cell for a clean electricity generation. A photovoltaic module provided DC power to an electrolyzer, to produce 56 cm3/min of hydrogen which is fed to a fuel cell and generate electricity. This prototype was designed and manufactured to show the future energy scenario of renewable energy. For water electrolysis, p...

  11. The role of hydrogen and fuel cells to store renewable energy in the future energy network – potentials and challenges

    International Nuclear Information System (INIS)

    The penetration of renewable energy sources is expected to rapidly increase from 15% to 50% in 2050 due to their vital contribution to the global energy requirements, sustainability and quality of life in economical, environmental and health aspects. This huge rise highlights the necessity of development of energy storage systems, especially for intermittency renewable energies such as solar photovoltaic and wind turbine, in order to balance the energy network. In this study, renewable energy options including pumped hydro, pressurized air, flywheels, Li ion batteries, hydrogen and super-capacitors are compared based on a specific set of criteria. The criteria considered are energy/power density, ease of integration with the existing energy network, cost effectiveness, durability, efficiency and safety. Our study showed that storing renewable energy sources in the form of hydrogen through the electrolysis process is ranked as the most promising option considering the mentioned criteria. It brings about several benefits suggesting that hydrogen and fuel cells are promising contributors towards a more sustainable future, both in energy demand and environmental sustainability. - Highlights: • Energy storage technologies provide the balance in modern energy networks. • Storing renewable energy in the form of hydrogen via the electrolysis process is concluded to be the most promising option. • Hydrogen energy provides high energy density, low capital cost and easy integration with the existing energy network. • Hydrogen and fuel cell contribute to a more sustainable future

  12. Renewable Energy, Photovoltaic Systems Near Airfields. Electromagnetic Interference

    Energy Technology Data Exchange (ETDEWEB)

    Deline, Chris [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dann, Geoff [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-04-01

    Recent increases in photovoltaic (PV) systems on Department of the Navy (DON) land and potential siting near airfields prompted Commander, Naval Installations Command to fund the Naval Facilities Engineering Command to evaluate the impact of electromagnetic interference (EMI) from PV systems on airfield electronic equipment. Naval Facilities Engineering and Expeditionary Warfare Center tasked Department of Energy National Renewable Energy laboratory (NREL) to conduct the assessment. PV systems often include high-speed switching semiconductor circuits to convert the voltage produced by the PV arrays to the voltage needed by the end user. Switching circuits inherently produce electromagnetic radiation at harmonics of the switching frequency. In this report, existing literature is summarized and tests to measure emissions and mitigation methods are discussed. The literature shows that the emissions from typical PV systems are low strength and unlikely to cause interference to most airfield electronic systems. With diligent procurement and siting of PV systems, including specifications for FCC Part 15 Class A compliant equipment and a 250-foot setback from communication equipment, NREL anticipates little to no EMI impact on nearby communications or telemetry equipment.

  13. Controlling Self-Renewal and Differentiation of Stem Cells via Mechanical Cues

    OpenAIRE

    Nava, Michele M.; Raimondi, Manuela T.; Riccardo Pietrabissa

    2012-01-01

    The control of stem cell response in vitro, including self-renewal and lineage commitment, has been proved to be directed by mechanical cues, even in the absence of biochemical stimuli. Through integrin-mediated focal adhesions, cells are able to anchor onto the underlying substrate, sense the surrounding microenvironment, and react to its properties. Substrate-cell and cell-cell interactions activate specific mechanotransduction pathways that regulate stem cell fate. Mechanical factors, incl...

  14. A Process for the Implementation of New Renewable Energy Systems in a Building by Considering Environmental and Economic Effect

    OpenAIRE

    Chan-Joong Kim; Taehoon Hong; Jimin Kim; Daeho Kim; Dong-yeon Seo

    2015-01-01

    The excessive use of fossil fuels has led to global warming and air pollution. To solve these problems, interest in new renewable energy system (NRE system) has increased in recent years. In particular, photovoltaic, solar thermal heating, fuel cell and ground source heating system are actively implemented for achieving the zero energy building. Since the initial investment cost of the NRE system is quite expensive, it is necessary to conduct a feasibility study from the life cycle perspectiv...

  15. Optimization Techniques of Hybrid Renewable Energy System: A Review

    OpenAIRE

    Siddiqi, Dilruba; Prabuwono, Anton Satria; A, Hasniaty; Tahir, Zulkifli; A, Taufik

    2010-01-01

    The term renewable energy is energy derived from a broad spectrum of resources, all of which are based on self-renewing energy sources such as sunlight, wind, flowing water, the earth's internal heat, and biomass such as energy crops, agricultural and industrial waste, and municipal waste. These resources can be used to produce electricity for all economic sectors, fuels for transportation, and heat for buildings and industrial processes [1]. Germany has new targets for renewable energy b...

  16. Modeling sustainability in renewable energy supply chain systems

    Science.gov (United States)

    Xie, Fei

    This dissertation aims at modeling sustainability of renewable fuel supply chain systems against emerging challenges. In particular, the dissertation focuses on the biofuel supply chain system design, and manages to develop advanced modeling framework and corresponding solution methods in tackling challenges in sustaining biofuel supply chain systems. These challenges include: (1) to integrate "environmental thinking" into the long-term biofuel supply chain planning; (2) to adopt multimodal transportation to mitigate seasonality in biofuel supply chain operations; (3) to provide strategies in hedging against uncertainty from conversion technology; and (4) to develop methodologies in long-term sequential planning of the biofuel supply chain under uncertainties. All models are mixed integer programs, which also involves multi-objective programming method and two-stage/multistage stochastic programming methods. In particular for the long-term sequential planning under uncertainties, to reduce the computational challenges due to the exponential expansion of the scenario tree, I also developed efficient ND-Max method which is more efficient than CPLEX and Nested Decomposition method. Through result analysis of four independent studies, it is found that the proposed modeling frameworks can effectively improve the economic performance, enhance environmental benefits and reduce risks due to systems uncertainties for the biofuel supply chain systems.

  17. Argonaute-2-null embryonic stem cells are retarded in self-renewal and differentiation

    Indian Academy of Sciences (India)

    P Chandra Shekar; Adnan Naim; D Partha Sarathi; Satish Kumar

    2011-09-01

    RNA interference (RNAi) pathways regulate self-renewal and differentiation of embryonic stem (ES) cells. Argonaute 2 (Ago2) is a vital component of RNA-induced silencing complex (RISC) and the only Ago protein with slicer activity. We generated Ago2-deficient ES cells by conditional gene targeting. Ago2-deficient ES cells are defective in the small-RNA-mediated gene silencing and are significantly compromised in biogenesis of mature microRNA. The self-renewal rate of Ago2-deficient ES cells is affected due to failure of silencing of Cdkn1a by ES-cell-specific microRNAs (miRNA) in the absence of Ago2. Interestingly, unlike Dicer- and Dgcr8-deficient ES cells, they differentiate to all three germ layers both in vivo and in vitro. However, early differentiation of Ago2-deficient ES cells is delayed by 2–4 days as indicated by persistence of higher levels of self-renewal/ pluripotency markers during differentiation. Further, appearance of morphological and differentiation markers is also delayed during the differentiation. In this study we show that Ago2 is essential for normal self-renewal and differentiation. Also, our data suggest that self-renewal and differentiation of ES cells are regulated by both siRNA and miRNA pathways.

  18. Advanced superconducting power conditioning system with SMES for effective use of renewable energy

    Science.gov (United States)

    Hamajima, T.; Tsuda, M.; Miyagi, D.; Amata, H.; Iwasaki, T.; Son, K.; Atomura, N.; Shintomi, T.; Makida, Y.; Takao, T.; Munakata, K.; Kajiwara, M.

    Since it is an urgent issue to reduce the global Carbon-dioxide in the world, renewable energy should be supplied as a large amount of the electric power. However, if a large amount of fluctuating renewable energy becomes more than adjustable amount of a utility grid capacity, instabilities such as frequency deviation might occur. We propose a system that is composed of SMES and FC-H2-Electrolyzer and also installed adjacent to Liquid Hydrogen station to cool down the SMES. Since the SMES has potentials of quick response and large I/O power, and Fuel Cell has potentials of slow response and steady power supplied from a large amount of hydrogen, we combine both storage devices and apply them to suppress the fluctuating power. We convert the fluctuating power to the constant power by using a developed prediction technology of Kalman filter to predict a trend of the fluctuating power. While the trend power should be supplied by FC or absorbed by the electrolyzer to produce hydrogen, the power difference between the renewable power and the trend power should be stored by the SMES. We simulate the power balance and analyze the required SMES capacity, design the concept of the SMES, and propose an operation algorithm for the SMES to estimate the electric efficiency of the system. It is found that the electric efficiency of the ASPCS can become greater than that of a pumped hydro-machine.

  19. Methamphetamine decreases dentate gyrus stem cell self-renewal and shifts the differentiation towards neuronal fate

    OpenAIRE

    Sofia Baptista; Charlène Lasgi; Caroline Benstaali; Nuno Milhazes; Fernanda Borges; Carlos Fontes-Ribeiro; Fabienne Agasse; Ana Paula Silva

    2014-01-01

    Methamphetamine (METH) is a highly addictive psychostimulant drug of abuse that negatively interferes with neurogenesis. In fact, we have previously shown that METH triggers stem/progenitor cell death and decreases neuronal differentiation in the dentate gyrus (DG). Still, little is known regarding its effect on DG stem cell properties. Herein, we investigate the impact of METH on mice DG stem/progenitor cell self-renewal functions. METH (10 nM) decreased DG stem cell self-renewal, while 1 nM...

  20. Renewable energy in energy efficient, low-pollution systems

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Bengt

    1997-03-01

    Energy use accounts for the dominating fraction of total sulphur dioxide (SO{sub 2}), nitrogen oxide (NO{sub x}), volatile organic compounds (VOCs) and carbon dioxide (CO{sub 2}) emissions. In this thesis, different strategies for reducing these emissions are evaluated, using a bottom-up approach. CO{sub 2} emissions from electricity and heat production in western Scania, Sweden, can be reduced by 25% and the emissions of acidifying gases (SO{sub 2} and NO{sub x}) by 50% by the year 2010, compared with 1988 levels, using energy systems based on efficient end-use technologies, cogeneration of heat and electricity, renewable energy sources and low-pollution energy conversion technologies. Exhaust-pipe NO{sub x} emissions from the Swedish transportation sector can be reduced by 50 percent by the year 2015, compared with 1991, by implementing the best available vehicle technologies. Exhaust-pipe emissions of CO{sub 2} can be stabilized at the 1991 level. With further technical development and the use of fuels from renewable sources of energy, NO{sub x} emissions can be reduced by 75 percent and CO{sub 2} emissions by 80 percent compared with 1991 levels. Swedish biomass resources are large, and, assuming production conditions around 2015, about 200 TWh/year could be utilised for energy. Major reductions in CO{sub 2} emissions could be achieved by substituting biomass for fossil fuels in heat, electricity and transportation fuel production. Transportation fuels produced from cellulosic biomass are likely to be less expensive than transportation fuels from conventional biomass feedstocks such as oil plants, sugar-beet and cereals. 90 refs, 3 figs, 5 tabs

  1. Benefits from a renewable energy village electrification system

    Energy Technology Data Exchange (ETDEWEB)

    Zahnd, Alex [Kathmandu University, School of Mechanical Engineering, and RIDS-Nepal - ISIS Humla Project Director (Nepal); Kimber, Haddix McKay [University of Montana and The ISIS Foundation, Missoula, Montana (United States)

    2009-02-15

    More than 100 years after Edison's life changing discovery, 1.6-2 billion people around the globe still live without light, in dark and smoke filled homes. The remote and impoverished Himalayan villages of upper Humla, in north-west Nepal, belong to some of the 2.4 billion people who still depend on the use of traditional biomass for their daily energy services such as cooking, heating and light. These activities on open fireplaces have a direct chronic impact on the health and extremely low life expectancy of the women and children along with devastating deforestation. There is a strong relationship between prosperity and access to electricity. The more remote and isolated communities in Nepal generally live in great poverty. Eighty percent of Nepal's 28.5 million people live in rural areas, with around half of these so remote, that neither a road, nor the national grid is ever likely to reach them. While Nepal has no fossil fuel resources, it is a country that is rich in renewable energy resources such as hydropower and solar energy. These abundant and locally available renewable energy resources can be tapped into with appropriate locally developed technologies. Generating and storing electrical energy derived from these rich local energy resources can provide for appropriate and sustainable lighting, which brings potential health, education, social and economic benefits to the people who have previously lived in homes with excessive indoor air pollution. This paper describes the living conditions of some villages in upper Humla, and the possible benefits of a simple village electrification system that provides basic lighting for the homes and the consequent improvements in the living conditions of the villagers. (author)

  2. Wireless embedded system with applications to renewable energy and energy efficiency

    OpenAIRE

    Rashidi, Younes

    2012-01-01

    Renewable sources of energy are considered as viable alternatives to cope with environmental issues related to non-renewable energies and the energy crisis of the current century. However, there are certain challenges in the production and consumption of renewable sources of energy. In this thesis, we study the problem of monitoring power production in photovoltaic (PV) solar energy systems and energy-efficient lighting control through wireless embedded microcontroller systems. In particular,...

  3. Hybrid renewable energy system application for electricity and heat supply of a residential building

    OpenAIRE

    Nakomčić-Smaragdakis Branka B.; Dragutinović Nataša G.

    2016-01-01

    Renewable and distributed energy systems could provide a solution to the burning issue of reliable and clean supply of energy, having in mind current state and future predictions for population growth and fossil fuel scarcity. Hybrid renewable energy systems are novelty in Serbia and warrant further detailed research. The aim of this paper is to analyze the application of renewable energy sources(RES) for electricity and heat supply of a typical household i...

  4. ERK1 phosphorylates Nanog to regulate protein stability and stem cell self-renewal

    Directory of Open Access Journals (Sweden)

    Sung-Hyun Kim

    2014-07-01

    Full Text Available Nanog regulates human and mouse embryonic stem (ES cell self-renewal activity. Activation of ERKs signaling negatively regulates ES cell self-renewal and induces differentiation, but the mechanisms are not understood. We found that ERK1 binds and phosphorylates Nanog. Activation of MEK/ERKs signaling and phosphorylation of Nanog inhibit Nanog transactivation, inducing ES cell differentiation. Conversely, suppression of MEK/ERKs signaling enhances Nanog transactivation to inhibit ES cell differentiation. We observed that phosphorylation of Nanog by ERK1 decreases Nanog stability through ubiquitination-mediated protein degradation. Further, we found that this phosphorylation induces binding of FBXW8 with Nanog to reduce Nanog protein stability. Overall, our results demonstrated that ERKs-mediated Nanog phosphorylation plays an important role in self-renewal of ES cells through FBXW8-mediated Nanog protein stability.

  5. Heating technologies for limiting biomass consumption in 100% renewable energy systems

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Connolly, David

    The utilisation of biomass poses large challenges in renewable energy systems and buildings account for a substantial part of the energy supply also in 100% renewable energy systems. The analyses of heating technologies show that district heating systems are especially important in limiting the...... dependence on biomass resources and to create cost effective systems. District heating systems are especially important in renewable energy systems with large amounts of fluctuating renewable energy sources as it enables fuel efficient and lower cost energy systems with thermal heat storages. And also...... district heating enables the use of combined heat and power production (CPH) and other renewable resources than biomass such as large-scale solar thermal, large-heat pumps, geothermal heat, industrial surplus heat etc. which is important for reducing the biomass consumption. Where the energy density in the...

  6. Roles of TGF-β family signaling in stem cell renewal and differentiation

    Institute of Scientific and Technical Information of China (English)

    Tetsuro Watabe; Kohei Miyazono

    2009-01-01

    Transforming growth factor(TGF)-βs and their family members,including bone morphogenetic proteins(BMPs),Nodal and acfivins.have been implicated in the development and maintenance of various organs,in which stem cells play important roles.Stem cells are characterized by their ability to seif-renew and to generate differentiated cells of a particular tissue.and are classifed into embryonic and somatic stem cells.Embryonic stem(ES)cells self-renew indefinitely and contribute to derivafives of all three primary germ layers.in contrast,somatic stem cells,which can be identified in various adult organs.exhibit Iimited abilities for self-renewal and differentiation in most cases.The multi-lineage differentiation capacity of ES cells and somatic stem cells has opened possibilities for cell replacement therapies for genetic.malignant and degenerative diseases.In order to utilize stem cells for therapeutic applications,it is essential to understand the extrinsic and intrinsic factors regulating self-renewal and differentiation of stem cells.More recently,induced pluripotent stem(iPS)cells have been generated from mouse and human fibroblasts that re-semble ES cells via ectopic expression of four transcription factors.iPS cells may have an advantage in regenerative medicine,since they overcome the immunogenicity and ethical controversy of ES cells.Moreover,recent studies have highlighted the involvement of cancer stem cells during the formation and progression of various types of cancers,including leukemia,glioma,and breast cancer.Here,we illustrate the roles of TGF-β family members in the mainte-nance and differentiation of ES cells,somatic stem cells,and cancer stem cells.

  7. Characterization of Hybrid Systems for Rural Electrification with Renewable Energies Using Geographic Information Systems (GIS)

    Energy Technology Data Exchange (ETDEWEB)

    Borda Angel, J. P.; Dominguez, J.; Amador, J.; Arribas, L.; Pinedo Pascua, I.

    2011-07-01

    The objective of this project is to redefine the algorithm of wind-diesel hybrid system implemented in IntiGIS. This methodology was developed by CIEMAT for the evaluation of rural electrification projects, comparing different renewable and conventional technologies based on their LEC or equivalent electrification cost. The analysis considers the social and geographical particularities of the study area. The core of the new model is the definition of renewable fraction in the wind-diesel hybrid system. To this end, it was assumed that the fraction of renewable will depend, first of all, of the wind speed. In this case, the objectives were to find a relationship between the renewable fraction and wind speed, expressed as a function, and also trying to demonstrate the influence of other parameters such as fuel price and consumption. The methodology used to achieve these objectives was to use HOMER to simulate technology and size of system components in order to obtain the optimal fraction renewable scenarios. Next, we examined how it varied with wind speed; we assessed the influence of other parameters and, finally, it is represented as a function of wind speed. After the redefinition of the algorithm, the changes were planned for inclusion in IntiGIS and tests were performed to validate the new model. (Author)

  8. A Review of Hybrid Renewable Energy Systems for Electric Power Generation

    Directory of Open Access Journals (Sweden)

    Md. Ibrahim

    2015-08-01

    Full Text Available Integration and combined utilization of renewable energy sources are becoming increasingly attractive. This paper is a review of hybrid renewable energy systems technologies for power generation, important issues and challenges in their design stage. Generation technology selection and unit sizing, System configurations and Energy management and control are discussed. Applications of hybrid energy systems, advantages of hybrid energy systems, issues and problems related to hybrid energy systems and an overview of energy storage technologies for renewable energy systems are presented. This paper also highlights the future trends of Hybrid energy systems, which represent a promising sustainable solution for power generation.

  9. Renewal of HOR Nuclear Instrumentation. From Analog to Digital System

    International Nuclear Information System (INIS)

    This paper describes the renewal of the nuclear instrumentation of the research reactor named HOR in Delft. This research reactor was built around 1960. Because of ageing effects, the nuclear instrumentation was completely replaced in 1980, together with the construction of a new control room outside the containment. In 2010, after 30 years of successful operation, it became a real challenge to repair the nuclear channels because of obsolete components. Of course, this problem was identified earlier, and a project was started in 2008 to select and replace the electronics of the nuclear channels. For this purpose a European tender was started to select a manufacturer for the new electronics in accordance with the requirements. The boundary conditions to be fulfilled by the manufacturer were: a) The functionality of the instrumentation and the interface to the plant should remain the same, and b) The proposed type of equipment should have been installed and commissioned successfully at other research reactors of comparable type earlier. Only the electronics should be replaced, detectors and cabling are reused. We selected a digital system based on two microcontrollers, each one checking the other one. It turned out to be a flexible system. It was easily adapted to our needs, showing adequate provisions for guaranteeing data integrity. In the summer maintenance period of 2010 the instrumentation was successfully installed and commissioned. This paper will describe the steps taken and the tests performed. (author)

  10. The first step towards a 100% renewable energy-system for Ireland

    DEFF Research Database (Denmark)

    Connolly, D.; Lund, Henrik; Mathiesen, Brian Vad;

    2011-01-01

    In 2007 Ireland supplied 96% of the total energy demand with fossil fuels (7% domestic and 89% imported) and 3% with renewable energy, even though there are enough renewable resources to supply all the energy required. As energy prices increase and the effects of global warming worsen, it is...... essential that Ireland begins to utilise its renewable resources more effectively. Therefore, this study presents the first step towards a 100% renewable energy-system for Ireland. The energy-system analysis tool used was EnergyPLAN, as it accounts for all sectors of the energy-system that need to be...... resource: biomass, hydrogen, and electricity. These energy-systems were compared so that the benefits from each could be used to create an ‘optimum’ scenario called combination. Although the results illustrate a potential 100% renewable energy-system for Ireland, they have been obtained based on numerous...

  11. A 100% renewable energy system in the year 2050: The case of Macedonia

    International Nuclear Information System (INIS)

    The most important problems the energy sector faces in Macedonia are an unfavourable energy mix with a high prevalence of lignite, a strong dependence on energy import, poor condition of the energy system and inefficiency in energy production and use. This paper investigates the prospects for realization of the 100% renewable energy system in Macedonia by making use of the EnergyPLAN model. Analysis was conducted for two renewable scenarios designed for the years 2030 and 2050. First scenario, the 50% renewable energy system, has been created for the year 2030 and represents the first step towards the 100% renewable energy future of Macedonia. The second scenario has been designed for the 100% renewable energy system based only on the renewable energy sources (RES) in the year 2050. Special attention in the design of these systems has been given to intermittent RES and to storage technologies. The analysis reveals that at the moment the 50% renewable energy system seems much more likely than the 100% renewable energy system, but with additional energy efficiency measures, which will lead to a decrease of consumption and with installation of new generation capacities this goal can be easily achieved.

  12. The molecular mechanism of embryonic stem cell pluripotency and self-renewal

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The self-renewal and pluripotency of embryonic stem cells (ESCs) is regulated by a network, which consists of a series of cell factors in microenviroments, a chain of transcription factors and certain signal conduction pathways. This article reviews recent progress in this field to elucidate the mechanism involved.

  13. Power electronics - The key technology for Renewable Energy Systems

    OpenAIRE

    Blaabjerg, Frede; Ma, Ke; Yang, Yongheng

    2014-01-01

    The energy paradigms in many countries (e.g. Germany and Denmark) have experienced a significant change from fossil-based resources to clean renewables (e.g. wind turbines and photovoltaics) in the past few decades. The scenario of highly penetrated renewables is going to be further enhanced - Denmark expects to be 100 % fossil-free by 2050. Consequently, it is required that the production, distribution and use of the energy should be as technologically efficient as possible and incentives to...

  14. Renewal processes

    CERN Document Server

    Mitov, Kosto V

    2014-01-01

    This monograph serves as an introductory text to classical renewal theory and some of its applications for graduate students and researchers in mathematics and probability theory. Renewal processes play an important part in modeling many phenomena in insurance, finance, queuing systems, inventory control and other areas. In this book, an overview of univariate renewal theory is given and renewal processes in the non-lattice and lattice case are discussed. A pre-requisite is a basic knowledge of probability theory.

  15. Nrf2 is required to maintain the self-renewal of glioma stem cells

    International Nuclear Information System (INIS)

    Glioblastomas are deadly cancers that display a functional cellular hierarchy maintained by self-renewing glioma stem cells (GSCs). Self-renewal is a complex biological process necessary for maintaining the glioma stem cells. Nuclear factor rythroid 2-related factor 2(Nrf2) plays a significant role in protecting cells from endogenous and exogenous stresses. Nrf2 is a key nuclear transcription factor that regulates antioxidant response element (ARE)-containing genes. Previous studies have demonstrated the significant role of Nrf2 in the proliferation of glioblastoma, and in their resistance to radioactive therapies. We examined the effect of knocking down Nrf2 in GSCs. Nrf2 expression was down-regulated by shRNA transinfected with lentivirus. Expression levels of Nestin, Nrf2, BMI-1, Sox2 and Cyclin E were assessed by western blotting, quantitative polymerase chain reaction (qPCR) and immunohistochemistry analysis. The capacity for self-renewal in vitro was assessed by genesis of colonies. The capacity for self-renewal in vivo was analyzed by tumor genesis of xenografts in nude mice. Knockdown of Nrf2 inhibited the proliferation of GSCs, and significantly reduced the expression of BMI-1, Sox2 and CyclinE. Knocking down of Nrf2 changed the cell cycle distribution of GSCs by causing an uncharacteristic increase in the proportion of cells in the G2 phase and a decrease in the proportion of cells in the S phase of the cell cycle. Nrf2 is required to maintain the self-renewal of GSCs, and its down-regulation can attenuate the self-renewal of GSCs significantly

  16. DNA methylation in stem cell renewal and multipotency

    OpenAIRE

    Berdasco, María; Esteller, Manel

    2011-01-01

    Owing to their potential for differentiation into multiple cell types, multipotent stem cells extracted from many adult tissues are an attractive stem cell resource for the replacement of damaged tissues in regenerative medicine. The requirements for cellular differentiation of an adult stem cell are a loss of proliferation potential and a gain of cell-type identity. These processes could be restricted by epigenetic modifications that prevent the risks of lineage-unrelated gene expression or ...

  17. Nuclear Energy and Renewables. System Effects in Low-carbon Electricity Systems - Executive Summary

    International Nuclear Information System (INIS)

    This report addresses the increasingly important interactions of variable renewables and dispatchable energy technologies, such as nuclear power, in terms of their effects on electricity systems. These effects add costs to the production of electricity, which are not usually transparent. The report recommends that decision-makers should take into account such system costs and internalise them according to a 'generator pays' principle, which is currently not the case. Analysing data from six OECD/NEA countries, the study finds that including the system costs of variable renewables at the level of the electricity grid increases the total costs of electricity supply by up to one-third, depending on technology, country and penetration levels. In addition, it concludes that, unless the current market subsidies for renewables are altered, dispatchable technologies will increasingly not be replaced as they reach their end of life and consequently security of supply will suffer. This implies that significant changes in management and cost allocation will be needed to generate the flexibility required for an economically viable coexistence of nuclear energy and renewables in increasingly de-carbonised electricity systems. (authors)

  18. Metering systems and demand-side management models applied to hybrid renewable energy systems in micro-grid configuration

    International Nuclear Information System (INIS)

    This paper proposes a demand-side management model integrated to a metering system for hybrid renewable energy systems in micro-grid configuration. The proposal is based on the management problems verified in most of this kind of renewable hybrid systems installed in Brazil. The main idea is the implementation of a pre-paid metering system with some control functions that directly act on the consumer demand, restricting the consumption proportionally to the monthly availability of renewable energy. The result is a better distribution of the electricity consumption by month and by consumer, preventing that only one user, with larger purchasing power, consumes all the renewable energy available at some time period. The proportionality between the consumption and the renewable energy's availability has the objective to prevent a lack of energy stored and a high use of the diesel generator-set on months of low renewable potential. This paper also aims to contribute to the Brazilian regulation of renewable energy systems supplying micro-grids. - Highlights: ► Review of the Brazilian electricity regulation for small-scale isolated systems. ► Renewable systems are the most feasible option in several isolated communities. ► One proposal is to guarantee government subsidies for renewable energy systems. ► Smart electronic meters to create electricity restrictions for the consumers.

  19. Design, Engineering, and Construction of Photosynthetic Microbial Cell Factories for Renewable Solar Fuel Production

    Energy Technology Data Exchange (ETDEWEB)

    Lindblad, Peter; Lindberg, Pia; Stensjoe, Karin (Photochemistry and Molecular Science, Dept. of Chemistry-Aangstroem Laboratory, Uppsala Univ., Uppsala (Sweden)), E-mail: Peter.Lindblad@kemi.uu.se; Oliveira, Paulo (Instituto de Biologia Molecular e Celular, Porto (Portugal)); Heidorn, Thorsten (Bioforsk-Norwegian Inst. for Agricultural and Environmental Research, Aas Oslo, (Norway))

    2012-03-15

    There is an urgent need to develop sustainable solutions to convert solar energy into energy carriers used in the society. In addition to solar cells generating electricity, there are several options to generate solar fuels. This paper outlines and discusses the design and engineering of photosynthetic microbial systems for the generation of renewable solar fuels, with a focus on cyanobacteria. Cyanobacteria are prokaryotic microorganisms with the same type of photosynthesis as higher plants. Native and engineered cyanobacteria have been used by us and others as model systems to examine, demonstrate, and develop photobiological H{sub 2} production. More recently, the production of carbon-containing solar fuels like ethanol, butanol, and isoprene have been demonstrated. We are using a synthetic biology approach to develop efficient photosynthetic microbial cell factories for direct generation of biofuels from solar energy. Present progress and advances in the design, engineering, and construction of such cyanobacterial cells for the generation of a portfolio of solar fuels, e.g., hydrogen, alcohols, and isoprene, are presented and discussed. Possibilities and challenges when introducing and using synthetic biology are highlighted

  20. Heating technologies for limiting biomass consumption in 100% renewable energy systems

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Connolly, David

    2011-01-01

    building stock is not high enough for districts heating geothermal heat pumps can be recommended for individual heating systems, although the costs and biomass consumption is higher than the district heating solutions.......The utilisation of biomass poses large challenges in renewable energy systems and buildings account for a substantial part of the energy supply also in 100% renewable energy systems. The analyses of heating technologies show that district heating systems are especially important in limiting the...... dependence on biomass resources and to create cost effective systems. District heating systems are especially important in renewable energy systems with large amounts of fluctuating renewable energy sources as it enables fuel efficient and lower cost energy systems with thermal heat storages. And also...

  1. A High-Efficiency Voltage Equalization Scheme for Supercapacitor Energy Storage System in Renewable Generation Applications

    Directory of Open Access Journals (Sweden)

    Liran Li

    2016-06-01

    Full Text Available Due to its fast charge and discharge rate, a supercapacitor-based energy storage system is especially suitable for power smoothing in renewable energy generation applications. Voltage equalization is essential for series-connected supercapacitors in an energy storage system, because it supports the system’s sustainability and maximizes the available cell energy. In this paper, we present a high-efficiency voltage equalization scheme for supercapacitor energy storage systems in renewable generation applications. We propose an improved isolated converter topology that uses a multi-winding transformer. An improved push-pull forward circuit is applied on the primary side of the transformer. A coupling inductor is added on the primary side to allow the switches to operate under the zero-voltage switching (ZVS condition, which reduces switching losses. The diodes in the rectifier are replaced with metal-oxide-semiconductor field-effect transistors (MOSFETs to reduce the power dissipation of the secondary side. In order to simplify the control, we designed a controllable rectifying circuit to achieve synchronous rectifying on the secondary side of the transformer. The experimental results verified the effectiveness of the proposed design.

  2. Fip1 regulates mRNA alternative polyadenylation to promote stem cell self-renewal

    OpenAIRE

    Lackford, Brad; Yao, Chengguo; Charles, Georgette M.; Weng, Lingjie; Zheng, Xiaofeng; Choi, Eun-A; Xie, Xiaohui; Wan, Ji; Xing, Yi; Freudenberg, Johannes M.; Yang, Pengyi; Jothi, Raja; Hu, Guang; Shi, Yongsheng

    2014-01-01

    mRNA alternative polyadenylation (APA) plays a critical role in post-transcriptional gene control and is highly regulated during development and disease. However, the regulatory mechanisms and functional consequences of APA remain poorly understood. Here, we show that an mRNA 3′ processing factor, Fip1, is essential for embryonic stem cell (ESC) self-renewal and somatic cell reprogramming. Fip1 promotes stem cell maintenance, in part, by activating the ESC-specific APA profiles to ensure the ...

  3. System effects of nuclear energy and renewables in low-carbon electricity Systems

    International Nuclear Information System (INIS)

    Electricity produced by variable renewable energies significantly affects the economics of dispatchable power generators, in particular those of nuclear power, both in the short run and the long run; the outcome of these competing factors will depend on the amount of variable renewables being introduced, local conditions and the level of carbon prices. An assessment of grid-level system costs (including the costs for grid connection, extension and reinforcement, as well as the added costs for balancing and back-up, but excluding the financial costs of intermittency and the impacts on security of supply, the environment, siting and safety), reveals a considerable difference between those of dispatchable technologies and those of variable renewables. Using a common methodology and a broad array of country-specific data, the grid-level system costs for Finland, France, Germany, the Republic of Korea, the United Kingdom and the United States were calculated for nuclear, coal, gas, onshore wind, offshore wind and solar PV both at 10 pc and 30 pc penetration levels. Variable renewables are creating a market environment in which dispatchable technologies can no longer finance themselves through revenues in 'energy only' wholesale markets; this has serious implications for the security of electricity supplies. Four main policy recommendations are proposed

  4. REST controls self-renewal and tumorigenic competence of human glioblastoma cells.

    Directory of Open Access Journals (Sweden)

    Luciano Conti

    Full Text Available The Repressor Element 1 Silencing Transcription factor (REST/NRSF is a master repressor of neuronal programs in non-neuronal lineages shown to function as a central regulator of developmental programs and stem cell physiology. Aberrant REST function has been associated with a number of pathological conditions. In cancer biology, REST has been shown to play a tumor suppressor activity in epithelial cancers but an oncogenic role in brain childhood malignancies such as neuroblastoma and medulloblastoma. Here we examined REST expression in human glioblastoma multiforme (GBM specimens and its role in GBM cells carrying self-renewal and tumorigenic competence. We found REST to be expressed in GBM specimens, its presence being particularly enriched in tumor cells in the perivascular compartment. Significantly, REST is highly expressed in self-renewing tumorigenic-competent GBM cells and its knock down strongly reduces their self-renewal in vitro and tumor-initiating capacity in vivo and affects levels of miR-124 and its downstream targets. These results indicate that REST contributes to GBM maintenance by affecting its self-renewing and tumorigenic cellular component and that, hence, a better understanding of these circuitries in these cells might lead to new exploitable therapeutic targets.

  5. Impacts of Renewable Energy Quota System on China's Future Power Sector

    DEFF Research Database (Denmark)

    Xiong, Weiming; Zhang, Da; Mischke, Peggy; Zhang, Xiliang

    2014-01-01

    for the power sector, which requires certain fraction of renewable energy in total power generation for each province and grid zone. The quantitative studies on renewable energy quota for China are still very limited. Based on a least-cost and technology-rich power generation and transmission...... expansion model for China, this study examines the impacts of renewable energy quota system and carbon cap policy instruments on the future Chinese power sector. Various scenarios are examined toward 2030 and their future power generation mix, capacity installations and carbon emission are discussed. This...... study concludes that while the renewable quota alone would be drive significant increase of renewable generation in the long term, with slightly increase of system cost compared with carbon cap policy....

  6. GATA-3 REGULATES THE SELF-RENEWAL OF LONG-TERM HEMATOPOIETIC STEM CELLS

    Science.gov (United States)

    Frelin, Catherine; Herrington, Robert; Janmohamed, Salima; Barbara, Mary; Tran, Gary; Paige, Christopher J.; Benveniste, Patricia; Zuñiga-Pflücker, Juan-Carlos; Souabni, Abdallah; Busslinger, Meinrad; Iscove, Norman N

    2016-01-01

    Gata3 is expressed and required for differentiation and function throughout the T lymphocyte lineage. Despite evidence it may also be expressed in multipotent hematopoietic stem cells (HSC), any role in these cells has remained unclear. Here we show GATA3 was cytoplasmic in quiescent long-term stem cells from steady state bone marrow, but relocated to the nucleus when HSC cycle. Relocation depended on p38-MAPK signaling and was associated with diminished capacity for long-term reconstitution upon transfer to irradiated mice. Deletion of Gata3 enhanced repopulating capacity and augmented self-renewal of long term HSC in cell-autonomous fashion, without affecting cell cycle. These observations position Gata3 as a regulator of the balance between self-renewal and differentiation in HSC acting downstream of the p38 signaling pathway. PMID:23974957

  7. Hybrid systems to address seasonal mismatches between electricity production and demand in nuclear renewable electrical grids

    International Nuclear Information System (INIS)

    A strategy to enable zero-carbon variable electricity production with full utilization of renewable and nuclear energy sources has been developed. Wind and solar systems send electricity to the grid. Nuclear plants operate at full capacity with variable steam to turbines to match electricity demand with production (renewables and nuclear). Excess steam at times of low electricity prices and electricity demand go to hybrid fuel production and storage systems. The characteristic of these hybrid technologies is that the economic penalties for variable nuclear steam inputs are small. Three hybrid systems were identified that could be deployed at the required scale. The first option is the gigawatt-year hourly-to-seasonal heat storage system where excess steam from the nuclear plant is used to heat rock a kilometer underground to create an artificial geothermal heat source. The heat source produces electricity on demand using geothermal technology. The second option uses steam from the nuclear plant and electricity from the grid with high-temperature electrolysis (HTR) cells to produce hydrogen and oxygen. Hydrogen is primarily for industrial applications; however, the HTE can be operated in reverse using hydrogen for peak electricity production. The third option uses variable steam and electricity for shale oil production. -- Highlights: •A system is proposed to meet variable hourly to seasonal electricity demand. •Variable solar and wind electricity sent to the grid. •Base-load nuclear plants send variable steam for electricity and hybrid systems. •Hybrid energy systems can economically absorb gigawatts of variable steam. •Hybrid systems include geothermal heat storage, hydrogen, and shale-oil production

  8. Fuel Cell Electric Vehicle Evaluation; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, Jennifer; Sprik, Sam; Ainscough, Chris; Saur, Genevieve

    2015-06-10

    This presentation provides a summary of NREL's FY15 fuel cell electric vehicle evaluation project activities and accomplishments. It was presented at the U.S. Department of Energy Hydrogen and Fuel Cells Program 2015 Annual Merit Review and Peer Evaluation Meeting on June 10, 2015, in Arlington, Virginia.

  9. Review of the Optimal Design on a Hybrid Renewable Energy System

    OpenAIRE

    Wu Yuan-Kang; Chang Shih-Ming

    2016-01-01

    Hybrid renewable energy systems, combining various kinds of technologies, have shown relatively high capabilities to solve reliability problems and have reduced cost challenges. The use of hybrid electricity generation/storage technologies is reasonable to overcome related shortcomings. While the hybrid renewable energy system is attractive, its design, specifically the determination of the size of PV, wind, and diesel power generators and the size of energy storage system in each power stati...

  10. The p53 inhibitor, pifithrin-{alpha}, suppresses self-renewal of embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdelalim, Essam Mohamed, E-mail: essam_abdelalim@yahoo.com [Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Department of Cytology and Histology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522 (Egypt); Tooyama, Ikuo [Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan)

    2012-04-13

    Highlights: Black-Right-Pointing-Pointer We determine the role of p53 in ES cells under unstressful conditions. Black-Right-Pointing-Pointer PFT-{alpha} suppresses ES cell proliferation. Black-Right-Pointing-Pointer PFT-{alpha} induces ES cell cycle arrest. Black-Right-Pointing-Pointer PFT-{alpha} downregulates Nanog and cyclin D1. -- Abstract: Recent studies have reported the role of p53 in suppressing the pluripotency of embryonic stem (ES) cells after DNA damage and blocking the reprogramming of somatic cells into induced pluripotent stem (iPS) cells. However, to date no evidence has been presented to support the function of p53 in unstressed ES cells. In this study, we investigated the effect of pifithrin (PFT)-{alpha}, an inhibitor of p53-dependent transcriptional activation, on self-renewal of ES cells. Our results revealed that treatment of ES cells with PFT-{alpha} resulted in the inhibition of ES cell propagation in a dose-dependent manner, as indicated by a marked reduction in the cell number and colony size. Also, PFT-{alpha} caused a cell cycle arrest and significant reduction in DNA synthesis. In addition, inhibition of p53 activity reduced the expression levels of cyclin D1 and Nanog. These findings indicate that p53 pathway in ES cells rather than acting as an inactive gene, is required for ES cell proliferation and self-renewal under unstressful conditions.

  11. Energy efficiency and renewable energy systems in Portugal and Brazil

    DEFF Research Database (Denmark)

    Østergaard, Poul Alberg; Soares, Isabel; Ferreira, Paula

    2014-01-01

    This article presents a review of the energy situation in Brazil and Portugal; two countries which are both characterised by high utilisation of renewable energy sources though with differences between them. The article also introduces contemporary energy research conducted on the two countries and...

  12. Methamphetamine decreases dentate gyrus stem cell self-renewal and shifts the differentiation towards neuronal fate

    Directory of Open Access Journals (Sweden)

    Sofia Baptista

    2014-09-01

    Full Text Available Methamphetamine (METH is a highly addictive psychostimulant drug of abuse that negatively interferes with neurogenesis. In fact, we have previously shown that METH triggers stem/progenitor cell death and decreases neuronal differentiation in the dentate gyrus (DG. Still, little is known regarding its effect on DG stem cell properties. Herein, we investigate the impact of METH on mice DG stem/progenitor cell self-renewal functions. METH (10 nM decreased DG stem cell self-renewal, while 1 nM delayed cell cycle in the G0/G1-to-S phase transition and increased the number of quiescent cells (G0 phase, which correlated with a decrease in cyclin E, pEGFR and pERK1/2 protein levels. Importantly, both drug concentrations (1 or 10 nM did not induce cell death. In accordance with the impairment of self-renewal capacity, METH (10 nM decreased Sox2+/Sox2+ while increased Sox2−/Sox2− pairs of daughter cells. This effect relied on N-methyl-d-aspartate (NMDA signaling, which was prevented by the NMDA receptor antagonist, MK-801 (10 μM. Moreover, METH (10 nM increased doublecortin (DCX protein levels consistent with neuronal differentiation. In conclusion, METH alters DG stem cell properties by delaying cell cycle and decreasing self-renewal capacities, mechanisms that may contribute to DG neurogenesis impairment followed by cognitive deficits verified in METH consumers.

  13. Assessing renewables-to-electricity systems: a fuzzy expert system model

    International Nuclear Information System (INIS)

    The assessment of Renewables-to-Electricity Systems is a complex, time-consuming task and requires skilled, experienced engineers. This paper describes the on-going research effort that takes place in the development of a new Intelligent Approach, an efficient decision making tool in this problem based on the employment of the Expert Systems and Fuzzy Logic techniques. As far as expert knowledge representation is concerned, the proposed approach is based on Expert System techniques (rule-based methodology). Moreover, trying to assess a Renewables-to-Electricity project or several alternative ones, the analysis has to face, in general, a series of uncertainties. To handle effectively these uncertainties, a new methodology is proposed (by use of Fuzzy Sets Theory and Fuzzy Logic Techniques). The proposed Fuzzy Project Priority Index for each Renewables-to-Electricity System is very useful especially in decision-makers. In order to demonstrate the proposed intelligent fuzzy analysis-based approach a simple case study is provided, supposing that a legal entity is to assess and finally select/propose an electricity production system, which uses RES (wind energy OR solar energy to photovoltaic OR small hydro). As fuzzy variables are concerned the Life Cycle Analysis (versus equipment production, plant preparation, operation and decommissioning) and the Development Cost (versus firm capabilities, spillover effects and potential downside damage)

  14. Erk signaling suppresses embryonic stem cell self-renewal to specify endoderm

    DEFF Research Database (Denmark)

    Hamilton, William B; Brickman, Joshua M

    2014-01-01

    Fgf signaling via Erk activation has been associated with both neural induction and the generation of a primed state for the differentiation of embryonic stem cells (ESCs) to all somatic lineages. To dissect the role of Erk in both ESC self-renewal and lineage specification, we explored the...

  15. Regulation of embryonic stem cell self-renewal and differentiation by TGF-β family signaling

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Embryonic stem (ES) cells are characterized by their ability to indefinitely self-renew and potential to differentiate into all the cell lineages of the body. ES cells are considered to have potential applications in regenerative medicine. In particular, the emergence of an ES cell analogue-induced pluripotent stem (iPS) cells via somatic cell reprogramming by co-expressing a limited number of critical stemness-related transcriptional factors has solved the problem of obtaining patient-specific pluripotent cells, encouraging researchers to develop more specific and functional cell lineages from ES or iPS cells for broad therapeutic applications. ES cell fate choice is delicately controlled by a core transcriptional network, epigenetic modification profiles and complex signaling cascades both intrinsically and extrinsically. Of these signals, transforming growth factor β (TGF-β) family members, including TGF-β, bone morphogenetic protein (BMP), Activin and Nodal, have been reported to influence cell self-renewal and a broad spectrum of lineage differentiation in ES cells, in accordance with the key roles of TGF-β family signaling in early embryo development. In this review, the roles of TGF-β family signals in coordinating ES cell fate determination are summarized.

  16. Stem cells, senescence, neosis and self-renewal in cancer

    Directory of Open Access Journals (Sweden)

    Rajaraman Murali M

    2006-11-01

    Full Text Available Abstract We describe the basic tenets of the current concepts of cancer biology, and review the recent advances on the suppressor role of senescence in tumor growth and the breakdown of this barrier during the origin of tumor growth. Senescence phenotype can be induced by (1 telomere attrition-induced senescence at the end of the cellular mitotic life span (MLS* and (2 also by replication history-independent, accelerated senescence due to inadvertent activation of oncogenes or by exposure of cells to genotoxins. Tumor suppressor genes p53/pRB/p16INK4A and related senescence checkpoints are involved in effecting the onset of senescence. However, senescence as a tumor suppressor mechanism is a leaky process and senescent cells with mutations or epimutations in these genes escape mitotic catastrophe-induced cell death by becoming polyploid cells. These polyploid giant cells, before they die, give rise to several cells with viable genomes via nuclear budding and asymmetric cytokinesis. This mode of cell division has been termed neosis and the immediate neotic offspring the Raju cells. The latter inherit genomic instability and transiently display stem cell properties in that they differentiate into tumor cells and display extended, but, limited MLS, at the end of which they enter senescent phase and can undergo secondary/tertiary neosis to produce the next generation of Raju cells. Neosis is repeated several times during tumor growth in a non-synchronized fashion, is the mode of origin of resistant tumor growth and contributes to tumor cell heterogeneity and continuity. The main event during neosis appears to be the production of mitotically viable daughter genome after epigenetic modulation from the non-viable polyploid genome of neosis mother cell (NMC. This leads to the growth of resistant tumor cells. Since during neosis, spindle checkpoint is not activated, this may give rise to aneuploidy. Thus, tumor cells also are destined to die due to

  17. The integration of renewable energy sources into electric power transmission systems

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; Dykas, W.P.; Kirby, B.J.; Purucker, S.L. [Oak Ridge National Lab., TN (United States); Lawler, J.S. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-07-01

    Renewable energy technologies such as photovoltaics, solar thermal power plants, and wind turbines are nonconventional, environmentally attractive sources of energy that can be considered for electric power generation. Many of the areas with abundant renewable energy resources (very sunny or windy areas) are far removed from major load centers. Although electrical power can be transmitted over long distances of many hundreds of miles through high-voltage transmission lines, power transmission systems often operate near their limits with little excess capacity for new generation sources. This study assesses the available capacity of transmission systems in designated abundant renewable energy resource regions and identifies the requirements for high-capacity plant integration in selected cases. In general, about 50 MW of power from renewable sources can be integrated into existing transmission systems to supply local loads without transmission upgrades beyond the construction of a substation to connect to the grid. Except in the Southwest, significant investment to strengthen transmission systems will be required to support the development of high-capacity renewable sources of 1000 MW or greater in areas remote from major load centers. Cost estimates for new transmission facilities to integrate and dispatch some of these high-capacity renewable sources ranged from several million dollars to approximately one billion dollars, with the latter figure an increase in total investment of 35%, assuming that the renewable source is the only user of the transmission facility.

  18. The signal transduction pathways and molecules for ES cells self-renewal

    Institute of Scientific and Technical Information of China (English)

    LIU Na; LU Min

    2005-01-01

    Embryonic stem cells (ES cells) are derived from the inner cell mass (ICM) of blastocysts. ES cells can divide and produce identical copies of them over and over again (self-renewal) in vitro for a long time, and retain the capability of differentiating into all cell types when induced by appropriate signals. Their capability of multilineage differentiation might be exploited for cell-based therapies. Therefore, ES cells have a broad prospect in many clinical applications. To achieve success in the clinical applications, we have to understand how ES cells propagate and differentiate into specific cell types. The cytokine LIF can sustain the self-renewal of certain mouse ES cells (mES cells) through activation of the signal transduction pathway LIF/gp130/ STAT3. In this pathway the transcription factor STAT3 is a crucial factor. Furthermore, Oct-3/4 plays a very important role in maintaining the ES cell pluripotency. Oct-3/4 regulates embryo development through its co-factor Sox2 and Rox-1. Recently nanog, a new homeodomain gene, was found and it has been shown to be crucial for the renewal and pluripotency of ES cells. Three other signals BMP, Wnt and ERK also can influence differentiation and propagation of ES cells. This review article summarizes recent progress in this area, mainly focusing on the LIF signaling pathway and the transcription factors Oct-3/4 and Nanog. Although it is still unclear how these components cooperate, a model is presented here to provide a design for solving this problem.

  19. Human Capacity Building in Energy Efficiency and Renewable Energy System Maintenance for the Yurok Tribe

    Energy Technology Data Exchange (ETDEWEB)

    Engel, R. A.' Zoellick, J J.

    2007-07-31

    From July 2005 to July 2007, the Schatz Energy Research Center (SERC) assisted the Yurok Tribe in the implementation of a program designed to build the Tribe’s own capacity to improve energy efficiency and maintain and repair renewable energy systems in Tribal homes on the Yurok Reservation. Funding for this effort was provided by the U.S. Department of Energy’s Tribal Program under First Steps grant award #DE-FG36-05GO15166. The program’s centerpiece was a house-by-house needs assessment, in which Tribal staff visited and conducted energy audits at over fifty homes. The visits included assessment of household energy efficiency and condition of existing renewable energy systems. Staff also provided energy education to residents, evaluated potential sites for new household renewable energy systems, and performed minor repairs as needed on renewable energy systems.

  20. ABCG2 regulates self-renewal and stem cell marker expression but not tumorigenicity or radiation resistance of glioma cells

    Science.gov (United States)

    Wee, Boyoung; Pietras, Alexander; Ozawa, Tatsuya; Bazzoli, Elena; Podlaha, Ondrej; Antczak, Christophe; Westermark, Bengt; Nelander, Sven; Uhrbom, Lene; Forsberg-Nilsson, Karin; Djaballah, Hakim; Michor, Franziska; Holland, Eric C.

    2016-01-01

    Glioma cells with stem cell traits are thought to be responsible for tumor maintenance and therapeutic failure. Such cells can be enriched based on their inherent drug efflux capability mediated by the ABC transporter ABCG2 using the side population assay, and their characteristics include increased self-renewal, high stem cell marker expression and high tumorigenic capacity in vivo. Here, we show that ABCG2 can actively drive expression of stem cell markers and self-renewal in glioma cells. Stem cell markers and self-renewal was enriched in cells with high ABCG2 activity, and could be specifically inhibited by pharmacological and genetic ABCG2 inhibition. Importantly, despite regulating these key characteristics of stem-like tumor cells, ABCG2 activity did not affect radiation resistance or tumorigenicity in vivo. ABCG2 effects were Notch-independent and mediated by diverse mechanisms including the transcription factor Mef. Our data demonstrate that characteristics of tumor stem cells are separable, and highlight ABCG2 as a potential driver of glioma stemness. PMID:27456282

  1. Transmission needs across a fully renewable European power system

    CERN Document Server

    Rodriguez, Rolando A; Andresen, Gorm B; Heide, Dominik; Greiner, Martin

    2013-01-01

    The residual load and excess power generation of 27 European countries with a 100% penetration of variable renewable energy sources are explored in order to quantify the benefit of power transmission between countries. Estimates are based on extensive weather data, which allows for modelling of hourly mismatches between the demand and renewable generation from wind and solar photovoltaics. For separated countries, balancing is required to cover around 24% of the total annual energy consumption. This number can be reduced down to 15% once all countries are networked together with uncon- strained interconnectors. The reduction represents the maximum possible benefit of transmission for the countries. The total Net Transfer Capacity of the unconstrained interconnectors is roughly twelve times larger than current values. However, constrained interconnector capacities six times larger than the current values are found to provide 97% of the maximum possible benefit of cooperation. This motivates a detailed investig...

  2. Geographic Information Systems for the Regional Integration of Renewable Energies

    International Nuclear Information System (INIS)

    This report is based on the project: The GIS in the regional integration of Renewable Energies for decentralised electricity production; developed by CIEMAT (Spanish Energy Research Centre) and UPM (Polytechnic University of Madrid, Spain) since 1997. The objective of this project is to analyse, evaluate and improve the GIS methodologies for application in RE and how GIS can aid in the evaluation and simulation of influence of technical, socio economical and geographical parameters. This project begin with the review of SOLARGIS methodology. SOLARGIS was developed by an european research team (included CIEMAT) in the frame of JOULE II Programme. In the first place this report described the state of the art in the application of GIS to Renewable Energies. In second place, the SOLARGIS review tasks and the application of this new product to Lorca (Murcia Region in Spain). Finally, the report describes the methodology for the spatial sensibility analysis. (Author) 24 refs

  3. Aging and renewal events in sporadically modulated systems

    International Nuclear Information System (INIS)

    We describe a form of modulation, namely a dishomogeneous Poisson process whose event rate changes sporadically and randomly in time with a chosen prescription, so as to share many statistical properties with a corresponding non-Poisson renewal process. Using our prescription the correlation function and the waiting time distribution between events are the same. If we study a continuous-time random walk, where the walker has only two possible velocities, randomly established at the times of the events, we show that the two processes also share the same second moment. However, the modulated diffusion process undergoes a dynamical transition between superstatistics and a Levy walk process, sharing the scaling properties of the renewal process only asymptotically. The aging experiment - based on the evaluation of the waiting time for the next event, given a certain time distance between another previous event and the beginning of the observation - seems to be the key experiment to discriminate between the two processes

  4. Empowering self-renewal and differentiation: the role of mitochondria in stem cells

    OpenAIRE

    Rehman, Jalees

    2010-01-01

    Stem cells are characterized by their multi-lineage differentiation potential (pluripotency) and their ability for self-renewal, which permits them to proliferate while avoiding lineage commitment and senescence. Recent studies demonstrate that undifferentiated, pluripotent stem cells display lower levels of mitochondrial mass and oxidative phosphorylation, and instead preferentially use non-oxidative glycolysis as a major source of energy. Hypoxia is a potent suppressor of mitochondrial oxid...

  5. How to Establish Local Renewable Energy Scenarios in the Context of National Energy Systems

    OpenAIRE

    Thellufsen, Jakob Zinck

    2014-01-01

    In the transition to 100% renewable energy systems, the local and regional implementation of renewable energy becomes essential. To implement energy systems that fulfill national targets, local investments have to be made creating a need for local energy planning. However, challenges emerge when local energy plans must be related to each other and to national targets. For instance, in terms of the division of resources between the countryside and cities, the amount of biomass to be used, and ...

  6. Definition of a remuneration system for heat from renewable resources; Ausgestaltung einer Einspeiseverguetung fuer erneuerbare Waerme

    Energy Technology Data Exchange (ETDEWEB)

    Dettli, R.; Ott, W.; Philippen, D.; Umbricht, A.

    2009-06-15

    This report for the Swiss Federal Office of Energy (SFOE) deals with proposals for a remuneration system for heat obtained from renewable resources. Local and regional district heating systems cover around three percent of Swiss heating needs. The authors estimate that, if these systems were to be operated completely using renewable resources such as biomass, ambient heat and the renewable portion of heat from waste incineration, around seven per cent of needs could be met. Further, around 10,000 heating systems with a power of more than 350 kW could be operated with renewables. A further potential for the use of renewable heating resources can be found in wastewater treatment plants and industrial waste heat. Various obstacles and restraints on the use of renewable resources in the heating area are discussed. The idea of providing a cost-covering remuneration system for heat is discussed and compared with that for renewable electricity. The proposed system is discussed, which would provide investment subsidies, risk-coverage and project development subsidies. The report discusses the results of a market analysis and the differences to be found between the markets for electricity and heat. Existing promotional programs are noted and the aims of a possible remuneration system are discussed. A concept for a promotion program for renewable heat generation and the use of waste heat is introduced. The installations to be promoted and the amount of remuneration to be paid out are discussed. Finally, the costs and the effects of the proposed promotion scheme are discussed. A comprehensive appendix provides details on the proposed system and provides information on market volume, energy resources, networks and infrastructure, providers of heat energy, heat consumers and general conditions as far as factors such as pricing and legislation are concerned. Finally, the 'Climate Cent' foundation is commented on.

  7. Renewable energy powered membrane technology. 1. Development and characterization of a photovoltaic hybrid membrane system

    OpenAIRE

    Schaefer, Andrea; Broeckmann, A.; Richards, B.S.

    2007-01-01

    In isolated communities where potable water sources as well as energy grids are limited or nonexistent, treating brackish groundwater aquifers with small-scale desalination systems can be a viable alternative to existing water infrastructures. Given the unavailability of power in many such situations, renewable energy is an obvious solution to power such systems. However, renewable energy is an intermittent power supply and with regards to the performance of intermittently operated desalinati...

  8. Stability Enhancement of a Power System Containing High-Penetration Intermittent Renewable Generation

    OpenAIRE

    Jorge Morel; Shin'ya Obara; Yuta Morizane

    2015-01-01

    This paper considers the transient stability enhancement of a power system containing large amounts of solar and wind generation in Japan. Following the Fukushima Daiichi nuclear disaster there has been an increasing awareness on the importance of a distributed architecture, based mainly on renewable generation, for the Japanese power system. Also, the targets of CO2 emissions can now be approached without heavily depending on nuclear generation. Large amounts of renewable generation leads to...

  9. The Potential of Renewable Energy Systems in China

    OpenAIRE

    Liu, Wen; Lund, Henrik; Mathiesen, Brian Vad

    2009-01-01

    This paper discusses the prospective of renewable energy in the process of sustainable development in China. Along with the high-speed economic development and increasing energy consumption, the Chinese Government faces a growing pressure to maintain the balance between energy supply and demand as well as reduce environmental pollution. To ensure energy security and mitigate climate changes the inappropriate energy consumption structure should be changed. As an alternative, a suitable infrast...

  10. Financing off-grid systems for renewable energies

    International Nuclear Information System (INIS)

    There are around 2 billion people without access to grid electricity. Photovoltaic (PV) electricity generation for individual households and micro-hydro for villages are identified as two renewable energy technologies with enormous market potential. The major non-technical barrier to PV is lack of infrastructure and appropriate finance. A new project, the Photovoltaic Market Transformation Inititative (PV-MTI) is described as a serious attempt to address this barrier. (orig.)

  11. Matching renewable energy systems to village-level energy needs

    Energy Technology Data Exchange (ETDEWEB)

    Ashworth, J.H.; Neuendorffer, J.W.

    1980-06-01

    This report provides a five step process for matching alternative renewable energy technologies with energy needs in rural villages of developing countries. Analytic tools are given for each of the five steps as well as information that can be expected. Twelve characterization criteria are developed to assist in the matching process. Three of these criteria, called discrimination criteria, are used for preliminary screening of technology possibilities for each need. The other criteria address site-specific temporal, climatic, social, cultural, and environmental characteristics of the energy need, technology, and cost considerations. To illustrate the matching process, seven basic human needs for energy are matched with seven potential renewable energy technologies. The final portion of the paper discusses the advantages of such a matching process and the resources required to initiate such an effort within a development project. Specific recommendations are given for field-testing this process and actions that could be taken immediately in basic research and development, applied research and technology modification, demonstrations, and commercialization to assist in the future diffusion of renewable energy technologies to rural areas of developing countries.

  12. SCL, LMO1 and Notch1 Reprogram Thymocytes into Self-Renewing Cells

    Science.gov (United States)

    Rojas-Sutterlin, Shanti; Herblot, Sabine; Hébert, Josée; Sauvageau, Guy; Lemieux, Sébastien; Lécuyer, Eric; Veiga, Diogo F. T.; Hoang, Trang

    2014-01-01

    The molecular determinants that render specific populations of normal cells susceptible to oncogenic reprogramming into self-renewing cancer stem cells are poorly understood. Here, we exploit T-cell acute lymphoblastic leukemia (T-ALL) as a model to define the critical initiating events in this disease. First, thymocytes that are reprogrammed by the SCL and LMO1 oncogenic transcription factors into self-renewing pre-leukemic stem cells (pre-LSCs) remain non-malignant, as evidenced by their capacities to generate functional T cells. Second, we provide strong genetic evidence that SCL directly interacts with LMO1 to activate the transcription of a self-renewal program coordinated by LYL1. Moreover, LYL1 can substitute for SCL to reprogram thymocytes in concert with LMO1. In contrast, inhibition of E2A was not sufficient to substitute for SCL, indicating that thymocyte reprogramming requires transcription activation by SCL-LMO1. Third, only a specific subset of normal thymic cells, known as DN3 thymocytes, is susceptible to reprogramming. This is because physiological NOTCH1 signals are highest in DN3 cells compared to other thymocyte subsets. Consistent with this, overexpression of a ligand-independent hyperactive NOTCH1 allele in all immature thymocytes is sufficient to sensitize them to SCL-LMO1, thereby increasing the pool of self-renewing cells. Surprisingly, hyperactive NOTCH1 cannot reprogram thymocytes on its own, despite the fact that NOTCH1 is activated by gain of function mutations in more than 55% of T-ALL cases. Rather, elevating NOTCH1 triggers a parallel pathway involving Hes1 and Myc that dramatically enhances the activity of SCL-LMO1 We conclude that the acquisition of self-renewal and the genesis of pre-LSCs from thymocytes with a finite lifespan represent a critical first event in T-ALL. Finally, LYL1 and LMO1 or LMO2 are co-expressed in most human T-ALL samples, except the cortical T subtype. We therefore anticipate that the self-renewal network

  13. Fuel Consumption Analysis and Optimization of a Sustainable Energy System for a 100% Renewables Smart House

    DEFF Research Database (Denmark)

    Craciun, Vasile Simion; Blarke, Morten; Trifa, Viorel

    2012-01-01

    Continuous increasing of fuel prices due to the limited stock, together with their negative impact on the environment open the gates for new technologies, more environmental friendly resource and free to use resources like the ones used by renewable energies. In this paper an economic analysis and......) enabling options. In case of renewable energies, one main challenge is the discontinuity of generation which can be solved with planning and control optimization methods. The results of the economic analysis and the feasibility of the sustainable energy system for a 100% renewables SH show that this could...... a feasibility study of a sustainable energy system for a 100% renewables smart house (SH) in Denmark is presented. Due to the continuous increasing penetration levels of wind and solar power in today’s energy system call for the development of high efficiency optimizations and Smart Grid (SG...

  14. Design for micro-combined cooling, heating and power systems stirling engines and renewable power systems

    CERN Document Server

    2015-01-01

    ‘Design for Micro-Combined Cooling, Heating & Power Systems’ provides a manual for the technical and structural design of systems for supplying decentralised energy in residential buildings. It presents the micro-combined cooling, heating & power systems Stirling engines & renewable energy sources (mCCHP-SE-RES) systems in an accessible manner both for the public at large, and for professionals who conceive, design or commercialise such systems or their components.  The high performance levels of these systems are demonstrated within the final chapter by the results of an experiment in which a house is equipped with a mCCHP-SE-RES system. The reader is also familiarized with the conceptual, technical and legal aspects of modern domestic energy systems; the components that constitute these systems; and advanced algorithms for achieving the structural and technical design of such systems. In residential buildings, satisfying demands of durable development has gradually evolved from necessity to...

  15. Nuclear power: a promising back-up option to promote renewable penetration in the French power system? Topic: Renewable system integration

    OpenAIRE

    Cany, Camille; Mansilla, Christine; Da Costa, Pascal; Mathonnière, Gilles; Thomas, Jean Baptiste

    2014-01-01

    The general 3X20 European directive proposes renewable penetration goals. In France, 27% of the electricity is to be produced by renewable resources by 2020 and this share will be continuously growing up to 2050. Among these resources, some-like wind and solar-are not dispatchable, which triggers challenges to maintain the reliability target level of the power system, both in the short and long term. Wind and solar are expected to contribute to about 12% of the French electricity production i...

  16. Alveolar progenitor and stem cells in lung development, renewal and cancer

    OpenAIRE

    Desai, Tushar J.; Brownfield, Douglas G.; Krasnow, Mark A.

    2014-01-01

    Alveoli are gas-exchange sacs lined by squamous alveolar type (AT) 1 cells and cuboidal, surfactant-secreting AT2 cells. Classical studies suggested AT1 arise from AT2 cells, but recent studies propose other sources. Here we use molecular markers, lineage tracing, and clonal analysis to map alveolar progenitors throughout the mouse lifespan. We show that during development AT1 and AT2 cells arise directly from a bipotent progenitor, whereas after birth new AT1 derive from rare, self-renewing,...

  17. CD133+ gallbladder carcinoma cells exhibit self-renewal ability and tumorigenicity

    Science.gov (United States)

    Shi, Cheng-Jian; Gao, Jun; Wang, Min; Wang, Xin; Tian, Rui; Zhu, Feng; Shen, Ming; Qin, Ren-Yi

    2011-01-01

    AIM: To identify cancer stem cells (CSCs) in human gallbladder carcinomas (GBCs). METHODS: Primary GBC cells were cultured under serum-free conditions to produce floating spheres. The stem-cell properties of the sphere-forming cells, including self-renewal, differentiation potential, chemoresistance and tumorigenicity, were determined in vitro or in vivo. Cell surface expression of CD133 was investigated in primary tumors and in spheroid cells using flow cytometry. The sphere-colony-formation ability and tumorigenicity of CD133+ cells were assayed. RESULTS: In vitro culture experiments revealed that floating spheroids were generated from primary GBC cells, and these sphere-forming cells could generate new progeny spheroids in serum-free media. Spheroid cells were differentiated under serum-containing conditions with downregulation of the stem cell markers Oct-4, Nanog, and nestin (P < 0.05). The differentiated cells showed lower spheroid-colony-formation ability than the original spheroid cells (P < 0.05). Spheroid cells were more resistant to chemotherapeutic reagents than the congenetic adherent cells (P < 0.05). Flow cytometry showed enriched CD133+ population in sphere-forming cells (P < 0.05). CD133+ cells possessed high colony-formation ability than the CD133- population (P < 0.01). CD133+ cells injected into nude mice revealed higher tumorigenicity than their antigen-negative counterparts (P < 0.05). CONCLUSION: CD133 may be a cell surface marker for CSCs in GBC. PMID:21734809

  18. Optimizing the U.S. Electric System with a High Penetration of Renewables

    Science.gov (United States)

    Corcoran, B. A.; Jacobson, M. Z.

    2012-12-01

    As renewable energy generators are increasingly being installed throughout the U.S., there is growing interest in interconnecting diverse renewable generators (primarily wind and solar) across large geographic areas through an enhanced transmission system. This reduces variability in the aggregate power output, increases system reliability, and allows for the development of the best overall group of renewable technologies and sites to meet the load. Studies are therefore needed to determine the most efficient and economical plan to achieve large area interconnections in a future electric system with a high penetration of renewables. This research quantifies the effects of aggregating electric load and, separately, electric load together with diverse renewable generation throughout the ten Federal Energy Regulatory Commission (FERC) regions in the contiguous U.S. The effects of aggregating electric load alone -- including generator capacity capital cost savings, load energy shift operating cost savings, reserve requirement cost savings, and transmission costs -- were calculated for various groupings of FERC regions using 2006 data. Transmission costs outweighed cost savings due to aggregation in nearly all cases. East-west transmission layouts had the highest overall cost, and interconnecting ERCOT to adjacent FERC regions resulted in increased costs, both due to limited existing transmission capacity. Scenarios consisting of smaller aggregation groupings had the lowest overall cost. This analysis found no economic case for further aggregation of load alone within the U.S., except possibly in the West and Northwest. If aggregation of electric load is desired, then small, regional consolidations yield the lowest overall system cost. Next, the effects of aggregating electric load together with renewable electricity generation are being quantified through the development and use of an optimization tool in AMPL (A Mathematical Programming Language). This deterministic

  19. The histone demethylase Jarid1b is required for hematopoietic stem cell self-renewal

    DEFF Research Database (Denmark)

    Stewart, Morag H; Albert, Mareike; Sroczynska, Patrycja;

    2015-01-01

    Jarid1b/KDM5b is a histone demethylase that regulates self-renewal and differentiation in stem cells and cancer, however its function in hematopoiesis is unclear. Here, we find that Jarid1b is highly expressed in primitive hematopoietic compartments and is overexpressed in acute myeloid leukemias...... compromises hematopoietic stem cell (HSC) self-renewal capacity and suggest that Jarid1b is a positive regulator of HSC potential........ Constitutive genetic deletion of Jarid1b did not impact steady-state hematopoiesis. In contrast, acute deletion of Jarid1b from bone marrow increased peripheral blood T cells and, following secondary transplantation, resulted in loss of bone marrow reconstitution. Our results reveal that deletion of Jarid1b...

  20. Adipocytes promote prostate cancer stem cell self-renewal through amplification of the cholecystokinin autocrine loop

    Science.gov (United States)

    Tang, Kai-Dun; Liu, Ji; Jovanovic, Lidija; An, Jiyuan; Hill, Michelle M.; Vela, Ian; Lee, Terence Kin-Wah; Ma, Stephanie; Nelson, Colleen; Russell, Pamela J.; Clements, Judith A.; Ling, Ming-Tat

    2016-01-01

    Obesity has long been linked with prostate cancer progression, although the underlying mechanism is still largely unknown. Here, we report that adipocytes promote the enrichment of prostate cancer stem cells (CSCs) through a vicious cycle of autocrine amplification. In the presence of adipocytes, prostate cancer cells actively secrete the peptide hormone cholecystokinin (CCK), which not only stimulates prostate CSC self-renewal, but also induces cathepsin B (CTSB) production of the adipocytes. In return, CTSB facilitates further CCK secretion by the cancer cells. More importantly, inactivation of CCK receptor not only suppresses CTSB secretion by the adipocytes, but also synergizes the inhibitory effect of CTSB inhibitor on adipocyte-promoted prostate CSC self-renewal. In summary, we have uncovered a novel mechanism underlying the mutual interplay between adipocytes and prostate CSCs, which may help explaining the role of adipocytes in prostate cancer progression and provide opportunities for effective intervention. PMID:26700819

  1. Female germ cell renewal during the annual reproductive cycle in Ostariophysians fish.

    Science.gov (United States)

    Wildner, Daniel Dantas; Grier, Harry; Quagio-Grassiotto, Irani

    2013-03-01

    The objective was to characterize female germ cell renewal during the annual reproductive cycle in two species of ostariophysian fish with distinct reproductive strategies: a siluriform, Pimelodus maculatus, in which oocyte development is group synchronous and the annual reproductive period is short; and a characiform, Serrasalmus maculatus, with asynchronous oocyte development and a prolonged reproductive period. These reproductive strategies result in fish determinate and indeterminate fecundity, respectively. Annual reproductive phases were determined by biometric and histologic analysis of gonads and interpreted according to new proposals for phase classification and stages of oocyte development (with special attention to germinal epithelium activity). Histologically, there were two types of oogonia in the germinal epithelium: single oogonia and those in mitotic proliferation. Oogonial proliferation and their entry into meiosis resulted in formation of cell nests (clusters of cells in the ovarian lamellae). Morphometric analysis was used to estimate germ cell renewal. Based on numbers of single oogonia in the lamellar epithelium, and nests with proliferating oogonia or early prophase oocytes throughout the annual reproductive cycle, oogonial proliferation and entrance into meiosis were more intense during the regenerating phase and developing phase, but decreased sharply (P < 0.05) during the spawning-capable phase. Oogonial proliferation gradually recovered during the regressing phase. We concluded that, independent of species or features of the reproductive cycle, germ cell renewal occurred during the regenerating phase, ensuring availability of eggs for the spawning event. PMID:23317762

  2. Planning of community-scale renewable energy management systems in a mixed stochastic and fuzzy environment

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Y.P.; Tan, Q. [Environmental Systems Engineering Program, Faculty of Engineering, Unversity of Regina, Regina, Saskatchewan (Canada); Huang, G.H. [Environmental Systems Engineering Program, Faculty of Engineering, Unversity of Regina, Regina, Saskatchewan (Canada)]|[Chinese Research Academy of Environmental Science, Beijing Normal University, Beijing 100012-100875 (China); Yang, Z.F. [State Key Laboratory of Water Environment Simulation, School of Enviroment, Beijing Normal University, Beijing 100875 (China)

    2009-07-15

    In this study, an interval-parameter superiority-inferiority-based two-stage programming model has been developed for supporting community-scale renewable energy management (ISITSP-CREM). This method is based on an integration of the existing interval linear programming (ILP), two-stage programming (TSP) and superiority-inferiority-based fuzzy-stochastic programming (SI-FSP). It allows uncertainties presented as both probability/possibilistic distributions and interval values to be incorporated within a general optimization framework, facilitating the reflection of multiple uncertainties and complexities during the process of renewable energy management systems planning. ISITSP-CREM can also be used for effectively addressing dynamic interrelationships between renewable energy availabilities, economic penalties and electricity-generation deficiencies within a community scale. Thus, complexities in renewable energy management systems can be systematically reflected, highly enhancing applicability of the modeling process. The developed method has then been applied to a case of long-term renewable energy management planning for three communities. Useful solutions for the planning of renewable energy management systems have been generated. Interval solutions associated with different energy availabilities and economic penalties have been obtained. They can be used for generating decision alternatives and thus help decision makers identify desired policies under various economic and system-reliability constraints. The generated solutions can also provide desired energy resource/service allocation plans with a minimized system cost (or economic penalties), a maximized system reliability level and a maximized energy security. Tradeoffs between system costs and energy security can also be tackled. Higher costs will increase potential energy generation amount, while a desire for lower system costs will run into a risk of energy deficiency. They are helpful for supporting

  3. Renewable energy resources for distributed generation systems in South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Szewczuk, Stefan

    2010-09-15

    The South African Government has objective to provide universal access of electricity for its citizens and its electrification programme has been successful but focus has moved from numbers of connections to one of achieving sustainable socio-economic benefits. First-hand understanding was obtained of the complexity of socio-economic development where CSIR undertook a project in the rural areas of South Africa to identify electrification opportunities using renewable energy linked to economic activities. Lessons formed basis of a government funding implementation of pilot hybrid mini-grids to inform a future rollout. Results informed the development of distributed generation concepts and an integrated methodology.

  4. Integrating renewable energy in power systems: Challenges and solutions

    OpenAIRE

    Krakowski, Vincent; Assoumou, Edi; Maïzi, Nadia; Mazauric, Vincent

    2014-01-01

    Energy issues, such as greenhouses gas (GHG) emissions, resource scarcity and energy independency, are challenging the way we currently produce, transport and consume energy. For the long term, the EU has proposed a “Roadmap for moving to a competitive low-carbon economy in 2050”, which aims at an 80% to 95% reduction in GHG emissions compared to 1990. To achieve this goal, the main focus will be on renewable energy sources and the electrification of energy consumption. In the EU, the electri...

  5. Smart Energy Systems for coherent 100% renewable energy and transport solutions

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Connolly, David;

    2015-01-01

    The hypothesis of this paper is that in order to identify least cost solutions of the integration of fluctuating renewable energy sources into current or future 100% renewable energy supplies one has to take a Smart Energy Systems approach. This paper outline why and how to do so. Traditionally......, significant focus is put on the electricity sector alone to solve the renewable energy integration puzzle. Smart grid research traditionally focuses on ICT, smart meters, electricity storage technologies, and local (electric) smart grids. In contrast, the Smart Energy System focuses on merging the electricity......, heating and transport sectors, in combination with various intra-hour, hourly, daily, seasonal and biannual storage options, to create the flexibility necessary to integrate large penetrations of fluctuating renewable energy. However, in this paper we present the development and design of coherent Smart...

  6. Financial incentives to promote renewable energy systems in European electricity markets: a survey

    International Nuclear Information System (INIS)

    Renewable energy systems may contribute to sustainable development. Therefore, one of the challenges for energy policy is to ensure that renewable energy options have a fair opportunity to compete with other supply resources. This paper presents a survey on promotion mechanisms to enhance the market penetration of renewable energies in European electricity markets. Strategies include rebates and tax incentives, regulated rates, system benefit charges, bidding-oriented mechanisms and various types of green pricing programs. The paper concludes that efficient promotion mechanisms should focus on incentives per kWh generated rather than on rebates on the investment in generating capacity (kW), and that there is no one single program type which has the best application to the promotion of all renewable technologies. For example, enhanced buy-back rates work as a dissemination strategy for wind energy but they do not work for photovoltaics. (author)

  7. Second life battery energy storage system for enhancing renewable energy grid integration

    OpenAIRE

    Koch-Ciobotaru, Cosmin; Saez-de Ibarra, Andoni; Martinez-Laserna, Egoitz; Stroe, Daniel-Ioan; Swierczynski, Maciej; Rodríguez Cortés, Pedro

    2015-01-01

    Connecting renewable power plants to the grid must comply with certain codes and requirements. One requirement is the ramp rate constraint, which must be fulfilled in order to avoid penalties. As this service becomes compulsory with an increased grid penetration of renewable, all possible solutions must be explored especially that large battery energy storage systems are still expensive solutions. Thus, in order to make battery investment economic viable, the use of second life batteries is i...

  8. Understanding the Attitude-Behavior Gap for Renewable Energy Systems Using Behavioral Reasoning Theory

    OpenAIRE

    O'Driscoll, Aidan; Claudy, Marius; Peterson, Mark

    2013-01-01

    Consumer adoption of renewable energies is an important step towards less carbon-intensive and more sustainable energy systems. But despite growing ecological awareness and articulated preferences for green products, renewable energies face slow rates of diffusion in consumer markets. This has been hard to explain given consumers’ favorability to the concept of products that lower one’s impact on the natural environment. This study uses data from 254 homeowners in Ireland to investigate the p...

  9. Organizational precedents for ownership and management of decentralized renewable-energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Meunier, R.; Silversmith, J.A.

    1981-03-01

    Three existing organizational types that meet the decentralization criteria of local consumer ownership and control - cooperatives, Rural Electric Cooperatives, and municipal utilities - are examined. These three organizational precedents are analyzed in terms of their histories, structures, legal powers, sources of capital, and social and political aspects. Examples of related experiments with renewable energy technologies are given, and inferences are drawn regarding the organizations' suitability as vehicles for future implementation of decentralized renewable energy systems.

  10. Design for reliability in power electronics in renewable energy systems – status and future

    OpenAIRE

    Wang, Huai; Blaabjerg, Frede; Ma, Ke; Wu, Rui

    2013-01-01

    Advances in power electronics enable efficient and flexible interconnection of renewable sources, loads and electric grids. While targets concerning efficiency of power converters are within reach, recent research endeavors to predict and improve their reliability to ensure high availability, low maintenance costs, and therefore, low Levelized-Cost-of-Energy (LCOE) of renewable energy systems. This paper presents the prior-art Design for Reliability (DFR) process for power converters and addr...

  11. Stability Enhancement of a Power System Containing High-Penetration Intermittent Renewable Generation

    Directory of Open Access Journals (Sweden)

    Jorge Morel

    2015-06-01

    Full Text Available This paper considers the transient stability enhancement of a power system containing large amounts of solar and wind generation in Japan. Following the Fukushima Daiichi nuclear disaster there has been an increasing awareness on the importance of a distributed architecture, based mainly on renewable generation, for the Japanese power system. Also, the targets of CO2 emissions can now be approached without heavily depending on nuclear generation. Large amounts of renewable generation leads to a reduction in the total inertia of the system because renewable generators are connected to the grid by power converters, and transient stability becomes a significant issue. Simulation results show that sodium-sulfur batteries can keep the system in operation and stable after strong transient disturbances, especially for an isolated system. The results also show how the reduction of the inertia in the system can be mitigated by exploiting the kinetic energy of wind turbines.

  12. Porphyrin homeostasis maintained by ABCG2 regulates self-renewal of embryonic stem cells.

    Directory of Open Access Journals (Sweden)

    Jimmy Susanto

    Full Text Available BACKGROUND: Under appropriate culture conditions, undifferentiated embryonic stem (ES cells can undergo multiple self-renewal cycles without loss of pluripotency suggesting they must be equipped with specific defense mechanisms to ensure sufficient genetic stability during self-renewal expansion. The ATP binding cassette transporter ABCG2 is expressed in a wide variety of somatic and embryonic stem cells. However, whether it plays an important role in stem cell maintenance remains to be defined. METHODOLOGY/PRINCIPAL FINDINGS: Here we provide evidence to show that an increase in the level of ABCG2 was observed accompanied by ES colony expansion and then were followed by decreases in the level of protoporphyrin IX (PPIX indicating that ABCG2 plays a role in maintaining porphyrin homoeostasis. RNA-interference mediated inhibition of ABCG2 as well as functional blockage of ABCG2 transporter with fumitremorgin C (FTC, a specific and potent inhibitor of ABCG2, not only elevated the cellular level of PPIX, but also arrest the cell cycle and reduced expression of the pluripotent gene Nanog. Overexpression of ABCG2 in ES cells was able to counteract the increase of endogenous PPIX induced by treatment with 5-Aminolevulinic acid suggesting ABCG2 played a direct role in removal of PPIX from ES cells. We also found that excess PPIX in ES cells led to elevated levels of reactive oxygen species which in turn triggered DNA damage signals as indicated by increased levels of gammaH2AX and phosphorylated p53. The increased level of p53 reduced Nanog expression because RNA- interference mediated inhibition of p53 was able to prevent the downregulation of Nanog induced by FTC treatment. CONCLUSIONS/SIGNIFICANCE: The present work demonstrated that ABCG2 protects ES cells from PPIX accumulation during colony expansion, and that p53 and gammaH2AX acts as a downstream checkpoint of ABCG2-dependent defense machinery in order to maintain the self-renewal of ES cells.

  13. Compilation and review of methodologies for estimating the comparative electric power system costs for renewable energy systems. Working material

    International Nuclear Information System (INIS)

    This Working Material provides a review of methodologies for estimating the costs of renewable energy systems and the state of art knowledge on stochastic features and economic evaluation methodologies of renewable energy systems for electricity generation in a grid integrated system. It is expected that this material facilitates the wider access by interested persons to sources for relevant comparative assessment activities which are progressing in the IAEA. Refs, figs, tabs

  14. Unified System-Level Modeling of Intermittent Renewable Energy Sources and Energy Storage for Power System Operation

    OpenAIRE

    Heussen, Kai; Koch, Stephan; Ulbig, Andreas; Andersson, Goran

    2011-01-01

    The system-level consideration of inter- mittent renewable energy sources and small-scale en- ergy storage in power systems remains a challenge as either type is incompatible with traditional operation concepts. Non-controllability and energy-constraints are still considered contingent cases in market-based operation. The design of operation strategies for up to 100 % renewable energy systems requires an explicit consideration of non-dispatchable generation and stor- age capacities, as well a...

  15. Nuclear Energy and Renewables: System Effects in Low-carbon Electricity Systems : Method comments to a NEA report

    OpenAIRE

    Söder, Lennart

    2012-01-01

    OECD Nuclear Energy Agency (NEA) released a new report on 29 November 2012. The study recommends that decision-makers should take full electricity system costs into account in energy choices and that such costs should be internalised according to a “generator pays” principle. The study, entitled Nuclear Energy and Renewables: System Effects in Low-carbon Electricity Systems, addresses the increasingly important interactions of variable renewables and dispatchable energy technologies, such as ...

  16. Heterochromatin protein 1 promotes self-renewal and triggers regenerative proliferation in adult stem cells.

    Science.gov (United States)

    Zeng, An; Li, Yong-Qin; Wang, Chen; Han, Xiao-Shuai; Li, Ge; Wang, Jian-Yong; Li, Dang-Sheng; Qin, Yong-Wen; Shi, Yufang; Brewer, Gary; Jing, Qing

    2013-04-29

    Adult stem cells (ASCs) capable of self-renewal and differentiation confer the potential of tissues to regenerate damaged parts. Epigenetic regulation is essential for driving cell fate decisions by rapidly and reversibly modulating gene expression programs. However, it remains unclear how epigenetic factors elicit ASC-driven regeneration. In this paper, we report that an RNA interference screen against 205 chromatin regulators identified 12 proteins essential for ASC function and regeneration in planarians. Surprisingly, the HP1-like protein SMED-HP1-1 (HP1-1) specifically marked self-renewing, pluripotent ASCs, and HP1-1 depletion abrogated self-renewal and promoted differentiation. Upon injury, HP1-1 expression increased and elicited increased ASC expression of Mcm5 through functional association with the FACT (facilitates chromatin transcription) complex, which consequently triggered proliferation of ASCs and initiated blastema formation. Our observations uncover an epigenetic network underlying ASC regulation in planarians and reveal that an HP1 protein is a key chromatin factor controlling stem cell function. These results provide important insights into how epigenetic mechanisms orchestrate stem cell responses during tissue regeneration. PMID:23629965

  17. FGF, Insulin, and SMAD Signaling Cooperate for Avian Primordial Germ Cell Self-Renewal

    Directory of Open Access Journals (Sweden)

    Jemima Whyte

    2015-12-01

    Full Text Available Precise self-renewal of the germ cell lineage is fundamental to fertility and reproductive success. The early precursors for the germ lineage, primordial germ cells (PGCs, survive and proliferate in several embryonic locations during their migration to the embryonic gonad. By elucidating the active signaling pathways in migratory PGCs in vivo, we were able to create culture conditions that recapitulate this embryonic germ cell environment. In defined medium conditions without feeder cells, the growth factors FGF2, insulin, and Activin A, signaling through their cognate-signaling pathways, were sufficient for self-renewal of germline-competent PGCs. Forced expression of constitutively active MEK1, AKT, and SMAD3 proteins could replace their respective upstream growth factors. Unexpectedly, we found that BMP4 could replace Activin A in non-clonal growth conditions. These defined medium conditions identify the key molecular pathways required for PGC self-renewal and will facilitate efforts in biobanking of chicken genetic resources and genome editing.

  18. On-Site Renewable Energy and Green Buildings: A System-Level Analysis.

    Science.gov (United States)

    Al-Ghamdi, Sami G; Bilec, Melissa M

    2016-05-01

    Adopting a green building rating system (GBRSs) that strongly considers use of renewable energy can have important environmental consequences, particularly in developing countries. In this paper, we studied on-site renewable energy and GBRSs at the system level to explore potential benefits and challenges. While we have focused on GBRSs, the findings can offer additional insight for renewable incentives across sectors. An energy model was built for 25 sites to compute the potential solar and wind power production on-site and available within the building footprint and regional climate. A life-cycle approach and cost analysis were then completed to analyze the environmental and economic impacts. Environmental impacts of renewable energy varied dramatically between sites, in some cases, the environmental benefits were limited despite the significant economic burden of those renewable systems on-site and vice versa. Our recommendation for GBRSs, and broader policies and regulations, is to require buildings with higher environmental impacts to achieve higher levels of energy performance and on-site renewable energy utilization, instead of fixed percentages. PMID:27031788

  19. Load-following mode control of a standalone renewable/fuel cell hybrid power source

    International Nuclear Information System (INIS)

    Highlights: • A FC hybrid power source (HPS) fed by renewable energy sources (RESs) is proposed. • The fuel cell (FC) operates as a backup to RESs based on the load-following strategy. • The energy storage device (ESS) will operate in charge-sustaining mode during a load cycle. • The ESS optimal design considers the peaks of RESs power and the imposed SOC window. • The FC/RES/ESS HPS is ideal to be used for standalone plug-in charge station. - Abstract: A hybrid power source (HPS), fed by renewable energy sources (RESs) and fuel cell (FC) sources, with an energy storage device (ESS) to be suitable for distributed generation (DG) applications, is proposed herein. The RESs could be a combination of photovoltaic (PV) panels and wind turbines (WT) based on common DC-bus, which are used as the primary DC source. The FC operates as a backup, feeding only the insufficiency power from the RESs based on the load-following strategy. The battery/ultracapacitor hybrid ESS operates as an auxiliary source for supplying the power deficit based on dynamic power balance strategy (the transient power – mainly via the ultracapacitors stack, and the steady-state power – mainly via the FC and batteries stack). If the FC stack is designed and operates based on average load-following strategy, then the ESS will operate in charge-sustaining mode during a load cycle. This feature permits to optimize the batteries stack capacity and extend its life time as well. The ultracapacitors stack can be designed considering the peaks of RESs power on DC-bus and the imposed window for its state-of-charge (SOC). This FC/RES/ESS HPS is ideal to be used for standalone plug-in charge station (PCS) or as DG system grid connected. In the last case, which is not analyzed here, the energy management unit (EMU) that communicates with smart grid will establish the moments to match the HPS power demand with grid supply availability, stabilizing the grid. Using load and RES power profiles that have

  20. SIMULATION OF THE SYSTEMS WITH RENEWABLE ENERGY SOURCES USING HOMER SOFTWARE

    Directory of Open Access Journals (Sweden)

    FIRINCĂ S.D.

    2015-12-01

    Full Text Available This paper simulates by using the Homer software, distributed energy systems with capacity below 1 MW. Among the renewable energy sources are used wind and solar energy. For photovoltaic panels, we are considering two situations: fixed panels, oriented at 45 ° and panels with tracking system with two axis. Simulation results contain information regarding operation hours of the system throughout the year, energy produced from the renewable energy sources, energy consumption for the load, and excess of electrical energy. The Homer software also allows an economic analysis of these systems.

  1. Power fluctuation reduction methodology for the grid-connected renewable power systems

    Science.gov (United States)

    Aula, Fadhil T.; Lee, Samuel C.

    2013-04-01

    This paper presents a new methodology for eliminating the influence of the power fluctuations of the renewable power systems. The renewable energy, which is to be considered an uncertain and uncontrollable resource, can only provide irregular electrical power to the power grid. This irregularity creates fluctuations of the generated power from the renewable power systems. These fluctuations cause instability to the power system and influence the operation of conventional power plants. Overall, the power system is vulnerable to collapse if necessary actions are not taken to reduce the impact of these fluctuations. This methodology aims at reducing these fluctuations and makes the generated power capability for covering the power consumption. This requires a prediction tool for estimating the generated power in advance to provide the range and the time of occurrence of the fluctuations. Since most of the renewable energies are weather based, as a result a weather forecast technique will be used for predicting the generated power. The reduction of the fluctuation also requires stabilizing facilities to maintain the output power at a desired level. In this study, a wind farm and a photovoltaic array as renewable power systems and a pumped-storage and batteries as stabilizing facilities are used, since they are best suitable for compensating the fluctuations of these types of power suppliers. As an illustrative example, a model of wind and photovoltaic power systems with battery energy and pumped hydro storage facilities for power fluctuation reduction is included, and its power fluctuation reduction is verified through simulation.

  2. Growth factor treatment enhances vestibular hair cell renewal and results in improved vestibular function

    OpenAIRE

    Kopke, Richard D; Jackson, Ronald L; Li, Geming; Rasmussen, Mark D.; Hoffer, Michael E.; Frenz, Dorothy A.; Costello, Michael; Schultheiss, Peter; Van De Water, Thomas R.

    2001-01-01

    The vestibules of adult guinea pigs were lesioned with gentamicin and then treated with perilymphatic infusion of either of two growth factor mixtures (i.e., GF I or GF II). GF I contained transforming growth factor α (TGFα), insulin-like growth factor type one (IGF-1), and retinoic acid (RA), whereas GF II contained those three factors and brain-derived neurotrophic factor. Treatment with GF I significantly enhanced vestibular hair cell renewal in ototoxin-damaged ...

  3. Discovery of Power-Law Growth in the Self-Renewal of Heterogeneous Glioma Stem Cell Populations.

    Directory of Open Access Journals (Sweden)

    Michiya Sugimori

    Full Text Available Accumulating evidence indicates that cancer stem cells (CSCs drive tumorigenesis. This suggests that CSCs should make ideal therapeutic targets. However, because CSC populations in tumors appear heterogeneous, it remains unclear how CSCs might be effectively targeted. To investigate the mechanisms by which CSC populations maintain heterogeneity during self-renewal, we established a glioma sphere (GS forming model, to generate a population in which glioma stem cells (GSCs become enriched. We hypothesized, based on the clonal evolution concept, that with each passage in culture, heterogeneous clonal sublines of GSs are generated that progressively show increased proliferative ability.To test this hypothesis, we determined whether, with each passage, glioma neurosphere culture generated from four different glioma cell lines become progressively proliferative (i.e., enriched in large spheres. Rather than monitoring self-renewal, we measured heterogeneity based on neurosphere clone sizes (#cells/clone. Log-log plots of distributions of clone sizes yielded a good fit (r>0.90 to a straight line (log(% total clones = k*log(#cells/clone indicating that the system follows a power-law (y = xk with a specific degree exponent (k = -1.42. Repeated passaging of the total GS population showed that the same power-law was maintained over six passages (CV = -1.01 to -1.17. Surprisingly, passage of either isolated small or large subclones generated fully heterogeneous populations that retained the original power-law-dependent heterogeneity. The anti-GSC agent Temozolomide, which is well known as a standard therapy for glioblastoma multiforme (GBM, suppressed the self-renewal of clones, but it never disrupted the power-law behavior of a GS population.Although the data above did not support the stated hypothesis, they did strongly suggest a novel mechanism that underlies CSC heterogeneity. They indicate that power-law growth governs the self-renewal of heterogeneous

  4. Cerebral cell renewal in adult mice controls the onset of obesity.

    Directory of Open Access Journals (Sweden)

    Alexandra Gouazé

    Full Text Available The hypothalamus plays a crucial role in the control of the energy balance and also retains neurogenic potential into adulthood. Recent studies have reported the severe alteration of the cell turn-over in the hypothalamus of obese animals and it has been proposed that a neurogenic deficiency in the hypothalamus could be involved in the development of obesity. To explore this possibility, we examined hypothalamic cell renewal during the homeostatic response to dietary fat in mice, i.e., at the onset of diet-induced obesity. We found that switching to high-fat diet (HFD accelerated cell renewal in the hypothalamus through a local, rapid and transient increase in cell proliferation, peaking three days after introducing the HFD. Blocking HFD-induced cell proliferation by central delivery of an antimitotic drug prevented the food intake normalization observed after HFD introduction and accelerated the onset of obesity. This result showed that HFD-induced dividing brain cells supported an adaptive anorectic function. In addition, we found that the percentage of newly generated neurons adopting a POMC-phenotype in the arcuate nucleus was increased by HFD. This observation suggested that the maturation of neurons in feeding circuits was nutritionally regulated to adjust future energy intake. Taken together, these results showed that adult cerebral cell renewal was remarkably responsive to nutritional conditions. This constituted a physiological trait required to prevent severe weight gain under HFD. Hence this report highlighted the amazing plasticity of feeding circuits and brought new insights into our understanding of the nutritional regulation of the energy balance.

  5. Role of renewable energy policies in energy dependency in Finland: System dynamics approach

    International Nuclear Information System (INIS)

    Highlights: • A system dynamics model for evaluating renewable energy policies on dependency is proposed. • The model considers the role of diversification on dependency and security of energy supply in Finland. • Dependency on imported sources will decrease depends on the defined scenarios in Finland. - Abstract: Objective: We discuss the role of diversification on dependency and security of energy supply. A system dynamics model with especial focus on the role of renewable energy resources (as a portfolio) on Finland’s energy dependency is developed. The purpose is also to cover a part of research gap exists in the system dynamics modeling of energy security investigations. Methods: A causal loops diagram and a system dynamics model evaluate Finnish scenarios of renewable energy policies. The analysis describes the relationship between dynamic factors such as RE encouragement packages, dependency, and energy demand. Results: A causal loops diagram and a system dynamics model evaluate three different Finnish scenarios of renewable energy policies by 2020. Conclusion: Analysis shows that despite 7% electricity/heat consumption growth by 2020 in Finland, dependency on imported sources will decrease between 1% and 7% depend on the defined scenarios. Practice Implications: The proposed model not only helps decision makers to test their scenarios related to renewable energy polices, it can be implemented by other countries

  6. Power control based on particle swarm optimization of grid-connected inverter for hybrid renewable energy system

    International Nuclear Information System (INIS)

    Highlights: • Three PSO-based PI controllers for a grid-connected inverter were presented. • Two online PSO-based PI controllers were compared with an offline PSO-tuned PI. • The HRES and the inverter were evaluated under power changes and grid voltage sags. • Online ITAE-based PSO reduced ITAE (current THD) by 15.24% (5.32%) versus offline one. - Abstract: This paper is focused on the study of particle swarm optimization (PSO)-based PI controllers for the power control of a grid-connected inverter supplied from a hybrid renewable energy system. It is composed of two renewable energy sources (wind turbine and photovoltaic – PV – solar panels) and two energy storage systems (battery and hydrogen system, integrated by fuel cell and electrolyzer). Three PSO-based PI controllers are implemented: (1) conventional PI controller with offline tuning by PSO algorithm based on the integral time absolute error (ITAE) index; (2) PI controllers with online self-tuning by PSO algorithm based on the error; and (3) PI controllers with online self-tuning by PSO algorithm based on the ITAE index. To evaluate and compare the three controllers, the hybrid renewable energy system and the grid-connected inverter are simulated under changes in the active and reactive power values, as well as under a grid voltage sag. The results show that the online PSO-based PI controllers that optimize the ITAE index achieves the best response

  7. Pleiotrophin Regulates the Retention and Self-Renewal of Hematopoietic Stem Cells in the Bone Marrow Vascular Niche

    Directory of Open Access Journals (Sweden)

    Heather A. Himburg

    2012-10-01

    Full Text Available The mechanisms through which the bone marrow (BM microenvironment regulates hematopoietic stem cell (HSC fate remain incompletely understood. We examined the role of the heparin-binding growth factor pleiotrophin (PTN in regulating HSC function in the niche. PTN−/− mice displayed significantly decreased BM HSC content and impaired hematopoietic regeneration following myelosuppression. Conversely, mice lacking protein tyrosine phosphatase receptor zeta, which is inactivated by PTN, displayed significantly increased BM HSC content. Transplant studies revealed that PTN action was not HSC autonomous, but rather was mediated by the BM microenvironment. Interestingly, PTN was differentially expressed and secreted by BM sinusoidal endothelial cells within the vascular niche. Furthermore, systemic administration of anti-PTN antibody in mice substantially impaired both the homing of hematopoietic progenitor cells to the niche and the retention of BM HSCs in the niche. PTN is a secreted component of the BM vascular niche that regulates HSC self-renewal and retention in vivo.

  8. Momentum is increasing towards a flexible electricity system based on renewables

    Science.gov (United States)

    Mitchell, Catherine

    2016-02-01

    Total global energy use is rising, and remains based on fossil fuels. Yet, the challenge of climate change requires a deep decarbonization of our energy system. Here I argue that the global energy policy discourse is moving rapidly towards one of renewable, energy-efficient and flexible electricity systems. This is primarily because of a rapid take-up within a few countries of variable renewable electricity sources over the past decade, resulting from falling renewable electricity prices, new and more economic means of flexible system operation, and changing social preferences. This in turn has led to widespread and supportive public policy announcements. I also argue that a ‘no-regrets’ energy policy is one that increases the energy system flexibility. Although the changing discourse is welcome, it is not to say that the challenge of climate change has been met. Policy statements must be backed up by more effective governance support and pressure to speed up change.

  9. Generic Energy Matching Model and Figure of Matching Algorithm for Combined Renewable Energy Systems

    Directory of Open Access Journals (Sweden)

    J.C. Brezet

    2009-08-01

    Full Text Available In this paper the Energy Matching Model and Figure of Matching Algorithm which originally was dedicated only to photovoltaic (PV systems [1] are extended towards a Model and Algorithm suitable for combined systems which are a result of integration of two or more renewable energy sources into one. The systems under investigation will range from mobile portable devices up to the large renewable energy system conceivably to be applied at the Afsluitdijk (Closure- dike in the north of the Netherlands. This Afsluitdijk is the major dam in the Netherlands, damming off the Zuiderzee, a salt water inlet of the North Sea and turning it into the fresh water lake of the IJsselmeer. The energy chain of power supplies based on a combination of renewable energy sources can be modeled by using one generic Energy Matching Model as starting point.

  10. Transition from non-renewable to renewable energy sources: fuel cells in Antarctica as an economically attractive niche

    International Nuclear Information System (INIS)

    There is a growing amount of evidence that indicates that fuel cells might be commercially attractive in several market niches in Latin America; however, political approval of demonstration projects has been elusive. In this paper, the results of an economic study carried out on the assumption of introducing an environmentally friendly fuel, such as methanol, for feeding fuel cell systems for electricity generation and heat production in the six bases that Argentina has in Antarctica are reported. It is seen that, in this particular case, there is a net cost benefit, even if the assets resulting from diminishing pollution in Antarctica are not taken into account. (Author)

  11. Sizing of Energy Storage Systems for Output Smoothing of Renewable Energy Systems

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Renewable energy sources (RESs), such as photovoltaic (PV) and wind power generation, have the characteristics of random fluctuation and intermittence. The output of RESs should be smoothed to inhibit the adverse effects of RESs fluctuations on the power grid. The energy storage system (ESS) is playing a more and more important role in the application of RESs due to its discharge/charge characteristic. Therefore, the optimal planning and design of ESS is of vital importance because of the expensive cost of ESS.

  12. Power quality enhancement of renewable energy source power network using SMES system

    Energy Technology Data Exchange (ETDEWEB)

    Seo, H.R.; Kim, A.R.; Park, M. [Changwon National University, 9 Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of); Yu, I.K., E-mail: yuik@changwon.ac.kr [Changwon National University, 9 Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of)

    2011-11-15

    Power quality enhancement of a renewable energy source power network is performed by a real-toroidal-type SMES coil. SMES unit charges and discharges the HTS coil to mitigate the fluctuation of PV system output power. The grid connected PV and SMES system has been modeled and simulated using power-hard-in-the-loop simulation. The PHILS results demonstrated the effectiveness of the SMES system for enhancing power quality. This paper deals with power quality enhancement of renewable energy source power network using SMES system and describes the operation characteristics of HTS SMES system using real-toroidal-type SMES coil for smoothening the fluctuation of large-scale renewable energy source such as photovoltaic (PV) power generation system. It generates maximum power of PV array under various weather conditions. SMES unit charges and discharges the HTS coil to mitigate the fluctuation of PV system output power. The SMES unit is controlled according to the PV array output and the utility power quality conditions. The grid connected PV and SMES system has been modeled and simulated using power-hard-in-the-loop simulation (PHILS). The PHILS results demonstrated the effectiveness of the SMES system for enhancing power quality in power network including large-scale renewable energy source, especially PV power generation system.

  13. How to Establish Local Renewable Energy Scenarios in the Context of National Energy Systems

    DEFF Research Database (Denmark)

    Thellufsen, Jakob Zinck

    2014-01-01

    In the transition to 100% renewable energy systems, the local and regional implementation of renewable energy becomes essential. To implement energy systems that fulfill national targets, local investments have to be made creating a need for local energy planning. However, challenges emerge when...... unnecessary national development. This paper presents methodologies and tools that can assist the design of local energy strategies to include the interaction with national energy systems. The paper applies these methodologies and tools to the case of a local energy strategy in Denmark and shows the results...

  14. Stem cell self-renewal versus differentiation: Tumor suppressor Mei-P26 and miRNAs control the balance

    Institute of Scientific and Technical Information of China (English)

    Run Shen; Ting Xie

    2008-01-01

    @@ Stem cells, which can self-renew and produce different cell types, have been shown to be regulated by extrinsic signals and intrinsic factors. Drosophila ovarian germline stem cells (GSCs), representing one of the well-studied stem cells, continuously proliferate and generate differentiated cystoblasts, which further develop into oocytes.

  15. SIRT1 suppresses self-renewal of adult hippocampal neural stem cells.

    Science.gov (United States)

    Ma, Chen-Yan; Yao, Mao-jin; Zhai, Qi-wei; Jiao, Jian-wei; Yuan, Xiao-bing; Poo, Mu-ming

    2014-12-01

    The balance between self-renewal and differentiation of adult neural stem cells (aNSCs) is essential for the maintenance of the aNSC reservoir and the continuous supply of new neurons, but how this balance is fine-tuned in the adult brain is not fully understood. Here, we investigate the role of SIRT1, an important metabolic sensor and epigenetic repressor, in regulating adult hippocampal neurogenesis in mice. We found that there was an increase in SIRT1 expression during aNSC differentiation. In Sirt1 knockout (KO) mice, as well as in brain-specific and inducible stem cell-specific conditional KO mice, the proliferation and self-renewal rates of aNSCs in vivo were elevated. Proliferation and self-renewal rates of aNSCs and adult neural progenitor cells (aNPCs) were also elevated in neurospheres derived from Sirt1 KO mice and were suppressed by the SIRT1 agonist resveratrol in neurospheres from wild-type mice. In cultured neurospheres, 2-deoxy-D-glucose-induced metabolic stress suppressed aNSC/aNPC proliferation, and this effect was mediated in part by elevating SIRT1 activity. Microarray and biochemical analysis of neurospheres suggested an inhibitory effect of SIRT1 on Notch signaling in aNSCs/aNPCs. Inhibition of Notch signaling by a γ-secretase inhibitor also largely abolished the increased aNSC/aNPC proliferation caused by Sirt1 deletion. Together, these findings indicate that SIRT1 is an important regulator of aNSC/aNPC self-renewal and a potential mediator of the effect of metabolic changes. PMID:25468938

  16. The integration of renewable energies into the electricity systems of North Africa

    Energy Technology Data Exchange (ETDEWEB)

    Brand, Bernhard

    2015-11-01

    How can renewable energy sources be efficiently integrated into the North African electricity systems? By using techno-economic modeling methods, this book explores optimized electricity system expansion pathways until the year 2030 for the five North African countries - Morocco, Algeria, Tunisia, Libya and Egypt. The results indicate that renewable energy integration is actually a viable business case for the entire region, if wind and solar capacities are properly planned in conjunction with the conventional generation system and under consideration of the country-specific electricity supply-/demand patterns. Further aspects featured in this publication are the impact of renewable power on the transnational electricity transmission system and the question how decision making processes about renewable energy strategies can be improved in the North African context. The book is a contribution to the scientific literature about energy issues in the Middle East and North Africa (MENA), but also seeks to address political and industrial practitioners concerned with the development of the region's renewable energy future.

  17. The integration of renewable energies into the electricity systems of North Africa

    International Nuclear Information System (INIS)

    How can renewable energy sources be efficiently integrated into the North African electricity systems? By using techno-economic modeling methods, this book explores optimized electricity system expansion pathways until the year 2030 for the five North African countries - Morocco, Algeria, Tunisia, Libya and Egypt. The results indicate that renewable energy integration is actually a viable business case for the entire region, if wind and solar capacities are properly planned in conjunction with the conventional generation system and under consideration of the country-specific electricity supply-/demand patterns. Further aspects featured in this publication are the impact of renewable power on the transnational electricity transmission system and the question how decision making processes about renewable energy strategies can be improved in the North African context. The book is a contribution to the scientific literature about energy issues in the Middle East and North Africa (MENA), but also seeks to address political and industrial practitioners concerned with the development of the region's renewable energy future.

  18. Curtailment in a Highly Renewable Power System and Its Effect on Capacity Factors

    Directory of Open Access Journals (Sweden)

    Alexander Kies

    2016-06-01

    Full Text Available The capacity factor of a power plant is the ratio of generation over its potential generation. It is an important measure to describe wind and solar resources. However, the fluctuating nature of renewable power generation makes it difficult to integrate all generation at times. Whenever generation exceeds the load, curtailment or storage of energy is required. With increasing renewable shares in the power system, the level of curtailment will further increase. In this work, the influence of the curtailment on the capacity factors for a highly renewable German power system is studied. An effective capacity factor is introduced, and the implications for the distribution of renewable power plants are discussed. Three years of highly-resolved weather data were used to model wind and solar power generation. Together with historical load data and a transmission model, a possible future German power system was simulated. It is shown that effective capacity factors for unlimited transmission are strongly reduced by up to 60% (wind and 70% (photovoltaics and therefore of limited value in a highly renewable power system. Furthermore, the results demonstrate that wind power benefits more strongly from a reinforced transmission grid than photovoltaics (PV does.

  19. Inhibition of CXCL12/CXCR4 autocrine/paracrine loop reduces viability of human glioblastoma stem-like cells affecting self-renewal activity

    International Nuclear Information System (INIS)

    Cancer stem cells (CSCs) or tumor initiating cells (TICs) drive glioblastoma (GBM) development, invasiveness and drug resistance. Distinct molecular pathways might regulate CSC biology as compared to cells in the bulk tumor mass, representing potential therapeutic targets. Chemokine CXCL12 and its receptor CXCR4 control proliferation, invasion and angiogenesis in GBM cell lines and primary cultures, but little is known about their activity in GBM CSCs. We demonstrate that CSCs, isolated from five human GBMs, express CXCR4 and release CXCL12 in vitro, although different levels of expression and secretion were observed in individual cultures, as expected for the heterogeneity of GBMs. CXCL12 treatment induced Akt-mediated significant pro-survival and self-renewal activities, while proliferation was induced at low extent. The role of CXCR4 signaling in CSC survival and self-renewal was further demonstrated using the CXCR4 antagonist AMD3100 that reduced self-renewal and survival with greater efficacy in the cultures that released higher CXCL12 amounts. The specificity of CXCL12 in sustaining CSC survival was demonstrated by the lack of AMD3100-dependent inhibition of viability in differentiated cells derived from the same GBMs. These findings, although performed on a limited number of tumor samples, suggest that the CXCL12/CXCR4 interaction mediates survival and self-renewal in GBM CSCs with high selectivity, thus emerging as a candidate system responsible for maintenance of cancer progenitors, and providing survival benefits to the tumor

  20. Niche-independent symmetrical self-renewal of a mammalian tissue stem cell.

    Directory of Open Access Journals (Sweden)

    Luciano Conti

    2005-09-01

    Full Text Available Pluripotent mouse embryonic stem (ES cells multiply in simple monoculture by symmetrical divisions. In vivo, however, stem cells are generally thought to depend on specialised cellular microenvironments and to undergo predominantly asymmetric divisions. Ex vivo expansion of pure populations of tissue stem cells has proven elusive. Neural progenitor cells are propagated in combination with differentiating progeny in floating clusters called neurospheres. The proportion of stem cells in neurospheres is low, however, and they cannot be directly observed or interrogated. Here we demonstrate that the complex neurosphere environment is dispensable for stem cell maintenance, and that the combination of fibroblast growth factor 2 (FGF-2 and epidermal growth factor (EGF is sufficient for derivation and continuous expansion by symmetrical division of pure cultures of neural stem (NS cells. NS cells were derived first from mouse ES cells. Neural lineage induction was followed by growth factor addition in basal culture media. In the presence of only EGF and FGF-2, resulting NS cells proliferate continuously, are diploid, and clonogenic. After prolonged expansion, they remain able to differentiate efficiently into neurons and astrocytes in vitro and upon transplantation into the adult brain. Colonies generated from single NS cells all produce neurons upon growth factor withdrawal. NS cells uniformly express morphological, cell biological, and molecular features of radial glia, developmental precursors of neurons and glia. Consistent with this profile, adherent NS cell lines can readily be established from foetal mouse brain. Similar NS cells can be generated from human ES cells and human foetal brain. The extrinsic factors EGF plus FGF-2 are sufficient to sustain pure symmetrical self-renewing divisions of NS cells. The resultant cultures constitute the first known example of tissue-specific stem cells that can be propagated without accompanying

  1. Quantitation and renewal of alveolar and bronchiolar cell populations of rat lungs. Changes during some pathological processes

    International Nuclear Information System (INIS)

    The various cells of alveolar and bronchiolar tissues of rat lungs were studied qualitatively and quantitatively. In physiological conditions, the renewal rate of the cell populations is low and the frequency of the various cell types is constant. This stability, especially at the level of the alveolar tissue, was also found during the latency period and the development of radiation-induced lung cancers. A particular cellular population was demonstrated: marginated leukocyte pool at the level of the pulmonary circulation. This pool was different both qualitatively and quantitatively from the leukocytes of the systemic circulation and, in physiological conditions, behaved as a cellular reservoir of monocytes chiefly re-distributed according to the body needs. In pathological conditions, its fast migration contributed to the defence of the alveolar medium. A quantitative study of the renewal of alveolar macrophages showed that under 1 p. cent of the marginated leukocyte pool is used daily to keep up this population. This fraction undergoes a maturation stage by cellular division within the endoalveolar medium. In some pathological conditions, this division can be completely inhibited

  2. Global renewable energy-based electricity generation and smart grid system for energy security.

    Science.gov (United States)

    Islam, M A; Hasanuzzaman, M; Rahim, N A; Nahar, A; Hosenuzzaman, M

    2014-01-01

    Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for future energy security is presented. Results show that renewable energy resources are becoming more prevalent as more electricity generation becomes necessary and could provide half of the total energy demands by 2050. To satisfy the future energy demand, the smart grid system can be used as an efficient system for energy security. The smart grid also delivers significant environmental benefits by conservation and renewable generation integration. PMID:25243201

  3. Global Renewable Energy-Based Electricity Generation and Smart Grid System for Energy Security

    Directory of Open Access Journals (Sweden)

    M. A. Islam

    2014-01-01

    Full Text Available Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for future energy security is presented. Results show that renewable energy resources are becoming more prevalent as more electricity generation becomes necessary and could provide half of the total energy demands by 2050. To satisfy the future energy demand, the smart grid system can be used as an efficient system for energy security. The smart grid also delivers significant environmental benefits by conservation and renewable generation integration.

  4. Development and commercialization of renewable energy technologies in Canada: An innovation system perspective

    International Nuclear Information System (INIS)

    The increased environmental awareness coupled with the recent changes in the oil prices triggered the necessity of focusing on effective management of energy systems. Global climate change has caused many people to consider ways of reducing greenhouse gases Renewable energy has become an essential feature in curtailing emission of Green House Gases, while meeting the demand for energy. This paper presents an innovation system framework for development and diffusion of renewable energy technologies. The framework is used to identify opportunities for small and medium enterprises in the renewable energy sector. A case study on a successful development, installation and implementation of solar thermal systems households in Calgary, Alberta, by an entrepreneurial firm, is also presented. (author)

  5. Integrating Renewable Energy into the Transmission and Distribution System of the U. S. Virgin Islands

    Energy Technology Data Exchange (ETDEWEB)

    Burman, K.; Olis, D.; Gevorgian, V.; Warren, A.; Butt, R.; Lilienthal, P.; Glassmire, J.

    2011-09-01

    This report focuses on the economic and technical feasibility of integrating renewable energy technologies into the U.S. Virgin Islands transmission and distribution systems. The report includes three main areas of analysis: 1) the economics of deploying utility-scale renewable energy technologies on St. Thomas/St. John and St. Croix; 2) potential sites for installing roof- and ground-mount PV systems and wind turbines and the impact renewable generation will have on the electrical subtransmission and distribution infrastructure, and 3) the feasibility of a 100- to 200-megawatt power interconnection of the Puerto Rico Electric Power Authority (PREPA), Virgin Islands Water and Power Authority (WAPA), and British Virgin Islands (BVI) grids via a submarine cable system.

  6. A review of computer tools for analysing the integration of renewable energy into various energy systems

    DEFF Research Database (Denmark)

    Connolly, D.; Lund, Henrik; Mathiesen, Brian Vad;

    2010-01-01

    This paper includes a review of the different computer tools that can be used to analyse the integration of renewable energy. Initially 68 tools were considered, but 37 were included in the final analysis which was carried out in collaboration with the tool developers or recommended points...... of contact. The results in this paper provide the information necessary to identify a suitable energy tool for analysing the integration of renewable energy into various energy-systems under different objectives. It is evident from this paper that there is no energy tool that addresses all issues related...... to integrating renewable energy, but instead the ‘ideal’ energy tool is highly dependent on the specific objectives that must be fulfilled. The typical applications for the 37 tools reviewed (from analysing single-building systems to national energy-systems), combined with numerous other factors...

  7. Power electronic converter systems for direct drive renewable energy applications

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    This chapter presents power electronic conversion systems for wind and marine energy generation applications, in particular, direct drive generator energy conversion systems. Various topologies are presented and system design optimization and reliability are briefly discussed....

  8. A new hybrid PLL for Interconnecting Renewable Energy Systems to the Grid

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

    2012-01-01

    There is a need to develop new control strategies for interconnecting Renewable Energy Sources (RES) to the power system due to the ever increasing penetration of RES and in particular for wind power systems (WPS). The control strategies are typically based on a fast and accurate detection of the...

  9. MODELLING OF HEAT SUPPLY SYSTEM ON THE BASIS OF RENEWABLE ENERGY

    OpenAIRE

    Сацик, Віктор Олександрович; Дідай, Борис Миколайович

    2010-01-01

    There are presented the heat supply system on the basis of renewable energy with possible connection of a reserve (traditional) energy source that gives the chance to provide requirement for the heat supply, and also reliability and stability work of systems.

  10. ADAR1 Activation Drives Leukemia Stem Cell Self-Renewal by Impairing Let-7 Biogenesis.

    Science.gov (United States)

    Zipeto, Maria Anna; Court, Angela C; Sadarangani, Anil; Delos Santos, Nathaniel P; Balaian, Larisa; Chun, Hye-Jung; Pineda, Gabriel; Morris, Sheldon R; Mason, Cayla N; Geron, Ifat; Barrett, Christian; Goff, Daniel J; Wall, Russell; Pellecchia, Maurizio; Minden, Mark; Frazer, Kelly A; Marra, Marco A; Crews, Leslie A; Jiang, Qingfei; Jamieson, Catriona H M

    2016-08-01

    Post-transcriptional adenosine-to-inosine RNA editing mediated by adenosine deaminase acting on RNA1 (ADAR1) promotes cancer progression and therapeutic resistance. However, ADAR1 editase-dependent mechanisms governing leukemia stem cell (LSC) generation have not been elucidated. In blast crisis chronic myeloid leukemia (BC CML), we show that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1. In a humanized BC CML mouse model, combined JAK2 and BCR-ABL1 inhibition prevents LSC self-renewal commensurate with ADAR1 downregulation. Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1(E912A) mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs. Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing and LIN28B upregulation. A small-molecule tool compound antagonizes ADAR1's effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis. Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSCs with active JAK2 signaling. PMID:27292188

  11. ady State Analysis of Grid Connected Hybrid Renewable Energy Conversion Systems

    OpenAIRE

    DR.D. PADMA SUBRAMANIAN

    2014-01-01

    This paper presents an analysis on steady state behavior of grid connected hybrid renewable energy conversion systems (RECS). Modeling of Doubly Fed Induction Generator (DFIG) for Wind Energy Conversion system (WECS) and marine current energy system ,and modeling of PV module is presented. A procedure for incorporating WECS, marine current energy conversion system and solar energy conversion system into a power flow program is discussed. A gird interfaced power flow program is...

  12. Nuclear-Renewable Hybrid System Economic Basis for Electricity, Fuel, and Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Charles Forsberg; Steven Aumeier

    2014-04-01

    Concerns about climate change and altering the ocean chemistry are likely to limit the use of fossil fuels. That implies a transition to a low-carbon nuclear-renewable electricity grid. Historically variable electricity demand was met using fossil plants with low capital costs, high operating costs, and substantial greenhouse gas emissions. However, the most easily scalable very-low-emissions generating options, nuclear and non-dispatchable renewables (solar and wind), are capital-intensive technologies with low operating costs that should operate at full capacities to minimize costs. No combination of fully-utilized nuclear and renewables can meet the variable electricity demand. This implies large quantities of expensive excess generating capacity much of the time. In a free market this results in near-zero electricity prices at times of high nuclear renewables output and low electricity demand with electricity revenue collapse. Capital deployment efficiency—the economic benefit derived from energy systems capital investment at a societal level—strongly favors high utilization of these capital-intensive systems, especially if low-carbon nuclear renewables are to replace fossil fuels. Hybrid energy systems are one option for better utilization of these systems that consumes excess energy at times of low prices to make some useful product.The economic basis for development of hybrid energy systems is described for a low-carbon nuclear renewable world where much of the time there are massivequantities of excess energy available from the electric sector.Examples include (1) high-temperature electrolysis to generate hydrogen for non-fossil liquid fuels, direct use as a transport fuel, metal reduction, etc. and (2) biorefineries.Nuclear energy with its concentrated constant heat output may become the enabling technology for economically-viable low-carbon electricity grids because hybrid nuclear systems may provide an economic way to produce dispatachable variable

  13. Distribution system reconfiguration for energy loss reduction considering the variability of load and local renewable generation

    International Nuclear Information System (INIS)

    The interconnection of renewable energy sources with distribution systems is attracting increasing interest because these renewable sources are inexhaustible and nonpolluting. Wind and photovoltaic are among the most mature of these energy sources, and their penetration continues to increase. In this paper a method based on GA (genetic algorithm) is presented to investigate the distribution system reconfiguration problem taking into consideration the effect of load variation and the stochastic power generation of renewable DG (distributed generators units). The presented method determines the annual distribution network reconfiguration scheme considering switching operation costs in order to minimize annual energy losses by determining the optimal configuration for each season of the year. The uncertainties related to DG power and varying load are considered by the creation of a probabilistic generation-load model that combines all possible operating conditions of the renewable DG units with the probability of their occurrence, followed by the incorporation of this model into the reconfiguration problem. The constraints include the voltage limits, the line current limits, the radial topology, and feeding of all loads. In order to evaluate the effectiveness of the proposed method, both balanced and unbalanced distribution systems are used as case studies. - Highlights: • This paper determines seasonal configurations to minimize annual energy losses. • Effect of hourly, daily, weekly and monthly load variations is considered. • Impact of uncertainty of renewable DG units is considered. • Switching operation cost has been considered

  14. Renewable Energy Use in Smallholder Farming Systems: A Case Study in Tafresh Township of Iran

    Directory of Open Access Journals (Sweden)

    Hossein Shabanali Fami

    2010-03-01

    Full Text Available This study was conducted to investigate use of renewable energy and materials in smallholder farming system of the Tafresh township of Iran. The population of the study consisted of 2,400 small farmers working in the smallholder farming systems of the area, in which 133 people were selected as sample using Cochran formula and simple random sampling technique. In order to gather the information, a questionnaire was developed for the study and validated by the judgment of the experts in agricultural development and extension. The reliability of the main scales of the questionnaire was examined by Cronbach Alpha coefficients, which ranged from 0.7 to 0.93, indicating the tool of study is reliable. The findings revealed that the majority of the respondents use renewable energy and materials directly in its traditional forms without enabling technologies, and they lack the access to renewable technologies to improve the efficiency of energy use. They preferred fossil energy for many activities due to its lower cost and ease of access. The overall conclusion is that there are potentials and capacities for using renewable energies and materials in the farming systems of the Tafresh township. The government has to support and encourage the adoption of renewable technologies and abandon fossil fuels wherever possible.

  15. Isoflurane inhibits embryonic stem cell self-renewal through retinoic acid receptor.

    Science.gov (United States)

    Liu, Sheng; Zhang, Lei; Liu, Yi; Shen, Xia; Yang, Longqiu

    2015-08-01

    The commonly used inhalation anesthetic isoflurane could permeate rapidly through the placental barrier and induce toxicity to the central nervous system of the developing fetus. However, the effects of isoflurane in utero during early gestation are unknown. We therefore treated pregnant mice with 1.4% isoflurane for 2h per day for three days at day3.5 (E3.5) to day6.5 (E6.5) to investigated the toxicity of isoflurane. Pregnant mice were executed and the fetal mice were weighed and observed. Mouse ESCs (E14) was exposed to 2% isoflurane for 6h. Twenty-four hours later, self-renewal was examined with AP staining. Effects of isoflurane on the expression of RAR-γ were examined using Western blot. As a result, anesthesia with 1.4% isoflurane for 2 hour per day for 3 days reduced fetal growth and development. Isoflurane decreased self-renewal and the expression stemness genes (Nanog, Oct4, Sox2, and Lin28) in mESCs. Vitamin A attenuated the effects of isoflurane inducing self-renewal inhibition. In summary, Anesthesia with 1.4% isoflurane for 2h per day for 3 days reduced fetal growth and development. Moreover, isoflurane inhibits mESCs self-renewal through retinoic acid receptor. PMID:26349971

  16. Efficient energy control strategies for a Standalone Renewable/Fuel Cell Hybrid Power Source

    International Nuclear Information System (INIS)

    Highlights: • A load – following control that operates the battery in charge – sustained mode. • A real-time Maximum Efficiency Point Tracking control that saves hydrogen fuel. • A comparative study of four strategies to control the fueling rates of the fuel cell stack. • Four control strategy for the HPS under unknown RES and load power profile are analyzed. • An increase of 3–5% of fuel efficiency was observed for the best strategy proposed. - Abstract: In this paper, four energy control strategies are proposed and analyzed for the standalone Renewable/Fuel Cell Hybrid Power Source (RES/FC HPS). The concept of the load following (LF) and Maximum Efficiency Point Tracking (MEPT) is used to control the fueling rates. A standalone RES/FC HPS uses at least one Renewable Energy Sources (RES) and a Polymer Electrolyte Membrane (PEM) Fuel Cell (FC) as backup source. Photovoltaic (PV) array and wind turbines (WT) farm are used as RES and the surplus of energy during light load stages is stored in hydrogen tank via water electrolysis to fuel the PEMFC. Small-scale RESs and commercially available PEMFCs are interfaced to the common DC bus via power converters and then to the single-phase distribution grid through a voltage source inverter. RES/FC HPS seem to be an efficient alternative for supplying smart houses and isolated sites. This paper proposes a new supervision strategy of the Energy Management Unit (EMU) based on the LF control approach that assures a charge-sustaining (CS) mode for the Energy Storage System (ESS). So, the capacity of the batteries stack can be reduced at minimum if it is directly connected to the DC bus. The ultracapacitors stack compensates dynamically the power flow balance on the DC bus, regulating the DC voltage via a bidirectional buck-boost power converter. Thus, a semi-active hybrid topology is adopted for the ESS having the batteries stack. The MEPT loops ensure an optimized energy management of the RES/FC HPS. The LF

  17. Net-Zero Energy Buildings: A Classification System Based on Renewable Energy Supply Options

    Energy Technology Data Exchange (ETDEWEB)

    Pless, S.; Torcellini, P.

    2010-06-01

    A net-zero energy building (NZEB) is a residential or commercial building with greatly reduced energy needs. In such a building, efficiency gains have been made such that the balance of energy needs can be supplied with renewable energy technologies. Past work has developed a common NZEB definition system, consisting of four well-documented definitions, to improve the understanding of what net-zero energy means. For this paper, we created a classification system for NZEBs based on the renewable sources a building uses.

  18. Renewables in future power systems implications of technological learning and uncertainty

    CERN Document Server

    Wagner, Fabian

    2014-01-01

    The book examines the future deployment of renewable power from a normative point of view. It identifies properties characterizing the cost-optimal transition towards a renewable power system and analyzes the key drivers behind this transition. Among those drivers, particular attention is paid to technological cost reductions and the implications of uncertainty. From a methodological perspective, the main contributions of this book relate to the field of endogenous learning and uncertainty in optimizing energy system models. The primary objective here is closing the gap between the strand of l

  19. Economic effects of a high share of renewable energies on power systems

    OpenAIRE

    Bueno Lorenzo, Miriam

    2014-01-01

    The aim of this thesis is to study the participation of renewable energies in the Spanish power system. For this purpose, two kind of studies have been developed in the present work. On the one hand, the first part of the work aims to assess the participation of wind energy producers in the Spanish electricity market. On the other hand, the overall effects of an increased installed capacity of renewable energies on the power system are evaluated. Due to the intermittent nature and the low pre...

  20. Regional Energy Planning Tool for Renewable Integrated Low-Energy District Heating Systems

    DEFF Research Database (Denmark)

    Tol, Hakan; Dincer, Ibrahim; Svendsen, Svend

    2013-01-01

    Low-energy district heating systems, operating at low temperature of 55 °C as supply and 25°C as return, can be the energy solution as being the prevailing heating infrastructure in urban areas, considering future energy schemesaiming at increased exploitation of renewable energy sources together...... energy planning tool is described considered with various energy conversion systems based on renewable energy sources to be supplied to an integrated energy infrastructure involving a low-energy district heating, a district cooling, and an electricity grid. The developed tool is performed for two case...

  1. A 100% renewable power system for Europe - Let the weather and physics decide!

    DEFF Research Database (Denmark)

    Greiner, Martin; Heide, Dominik; Rasmussen, Morten Grud;

    The design of sustainable energy systems is no longer only the domain of politics, economics and engineering. Mathematical physics is able to contribute with its generic understanding of everything. A new modeling approach is presented and applied to design a fully renewable European power system....... This approach is based on weather data with good spatio-temporal resolution, which is first converted into wind and solar power generation and then used to derive estimates on the optimal mix between the renewable resources and the storage needs....

  2. Post-disaster resilience of a 100% renewable energy system in Japan

    International Nuclear Information System (INIS)

    Following the 2011 Fukushima nuclear disaster, Japan is having to re-design its energy policy. With the danger of nuclear power in an earthquake-prone country exposed, renewable energies are being seen as a potential alternative. An assessment of the feasibility of a 100% renewable energy electricity system in Japan by the year 2030 was shown to be able to achieve a higher level of electricity resilience. The assessment is based on a simulation of the hourly future electricity production based on wind and solar meteorological data, that can cope with the estimated future hourly electricity demand in Japan for the year 2030. Such as system would use pump-up storage and electric batteries to balance the daily fluctuations in supply and demand, though the most important challenge of the system would be providing sufficient electricity to meet the summer demand peak. These findings have import implications at the policy making level, as it shows that the Japanese electricity generation system is technically able to increase the share of renewables up to 100%, guaranteeing a stable and reliable supply. - Highlights: • Hourly simulation of a 100% renewable energy system in Japan. • Feasibility analysis of system reliability and risk of failure. • Use of car electric batteries to store electricity during night. • Analysis of policy implications to implement decentralized smart grid system

  3. Two major gate-keepers in the self-renewal of neural stem cells: Erk1/2 and PLCγ1 in FGFR signaling

    OpenAIRE

    Lee Jin-A; Jang Deok-Jin; Kaang Bong-Kiun

    2009-01-01

    Abstract Neural stem cells are undifferentiated precursor cells that proliferate, self-renew, and give rise to neuronal and glial lineages. Understanding the molecular mechanisms underlying their self-renewal is an important aspect in neural stem cell biology. The regulation mechanisms governing self-renewal of neural stem cells and the signaling pathways responsible for the proliferation and maintenance of adult stem cells remain largely unknown. In this issue of Molecular Brain [Ma DK et al...

  4. IEA-R1 renewed primary coolant piping system stress analysis

    International Nuclear Information System (INIS)

    A partial replacement of the IEA-R1 piping system was conducted in 2014. The aim of this work is to perform the stress analysis of the renewed primary piping system of the IEA-R1, taking into account the as built conditions and the pipe modifications. The nuclear research reactor IEA-R1 is a pool type reactor designed by Babcox-Willcox, which is operated by IPEN since 1957. The primary coolant system is responsible for removing the residual heat of the Reactor core. As a part of the life management, a regular inspection detected some degradation in the primary piping system. In consequence, part of the piping system was replaced. The partial renewing of the primary piping system did not imply in major piping layout modifications. However, the stress condition of the piping systems had to be reanalyzed. The structural stress analysis of the primary piping systems is now presented and the final results are discussed. (author)

  5. Evidence for self-renewing lung cancer stem cells and their implications in tumor initiation, progression, and targeted therapy

    OpenAIRE

    Sullivan, James P.; Minna, John D.; Shay, Jerry W.

    2010-01-01

    The discovery of rare tumor cells with stem cell features first in leukemia and later in solid tumors has emerged as an important area in cancer research. It has been determined that these stem-like tumor cells, termed cancer stem cells, are the primary cellular component within a tumor that drives disease progression and metastasis. In addition to their stem-like ability to self-renew and differentiate, cancer stem cells are also enriched in cells resistant to conventional radiation therapy ...

  6. Integrated operation of electric vehicles and renewable generation in a smart distribution system

    International Nuclear Information System (INIS)

    Highlights: • The contribution of electric vehicles to provide the reserve capacity is analyzed. • Decentralized energy and reserve scheduling in a distribution system is presented. • The integrated operation of renewable generation and electric vehicles is proposed. - Abstract: Distribution system complexity is increasing mainly due to technological innovation, renewable Distributed Generation (DG) and responsive loads. This complexity makes difficult the monitoring, control and operation of distribution networks for Distribution System Operators (DSOs). In order to cope with this complexity, a novel method for the integrated operational planning of a distribution system is presented in this paper. The method introduces the figure of the aggregator, conceived as an intermediate agent between end-users and DSOs. In the proposed method, energy and reserve scheduling is carried out by both aggregators and DSO. Moreover, Electric Vehicles (EVs) are considered as responsive loads that can participate in ancillary service programs by providing reserve to the system. The efficiency of the proposed method is evaluated on an 84-bus distribution test system. Simulation results show that the integrated scheduling of EVs and renewable generators can mitigate the negative effects related to the uncertainty of renewable generation

  7. A technical and economic analysis of one potential pathway to a 100% renewable energy system

    OpenAIRE

    David Connolly; Brian Vad Mathiesen

    2014-01-01

    This paper outlines how an existing energy system can be transformed into a 100% renewable energy system. The transition is divided into a number of key stages which reflect key radical technological changes on the supply side of the energy system. Ireland is used as a case study, but in reality this reflects many typical energy systems today which use power plants for electricity, individual boilers for heat, and oil for transport. The seven stages analysed are 1) reference, 2) introduction ...

  8. Pretreated Landfill Gas Conversion Process via a Catalytic Membrane Reactor for Renewable Combined Fuel Cell-Power Generation

    Directory of Open Access Journals (Sweden)

    Zoe Ziaka

    2013-01-01

    Full Text Available A new landfill gas-based reforming catalytic processing system for the conversion of gaseous hydrocarbons, such as incoming methane to hydrogen and carbon oxide mixtures, is described and analyzed. The exit synthesis gas (syn-gas is fed to power effectively high-temperature fuel cells such as SOFC types for combined efficient electricity generation. The current research work is also referred on the description and design aspects of permreactors (permeable reformers carrying the same type of landfill gas-reforming reactions. Membrane reactors is a new technology that can be applied efficiently in such systems. Membrane reactors seem to perform better than the nonmembrane traditional reactors. The aim of this research includes turnkey system and process development for the landfill-based power generation and fuel cell industries. Also, a discussion of the efficient utilization of landfill and waste type resources for combined green-type/renewable power generation with increased processing capacity and efficiency via fuel cell systems is taking place. Moreover, pollution reduction is an additional design consideration in the current catalytic processors fuel cell cycles.

  9. Review of the Optimal Design on a Hybrid Renewable Energy System

    Directory of Open Access Journals (Sweden)

    Wu Yuan-Kang

    2016-01-01

    Full Text Available Hybrid renewable energy systems, combining various kinds of technologies, have shown relatively high capabilities to solve reliability problems and have reduced cost challenges. The use of hybrid electricity generation/storage technologies is reasonable to overcome related shortcomings. While the hybrid renewable energy system is attractive, its design, specifically the determination of the size of PV, wind, and diesel power generators and the size of energy storage system in each power station, is very challenging. Therefore, this paper will focus on the system planning and operation of hybrid generation systems, and several corresponding topics and papers by using intelligent computing methods will be reviewed. They include typical case studies, modeling and system simulation, control and management, reliability and economic studies, and optimal design on a reliable hybrid generation system.

  10. Electricity generation from renewable energy sources in Italy: the costs of the System Inefficiencies

    International Nuclear Information System (INIS)

    The promotion of electricity from renewable energy sources (RES) is a high European Union (E U) priority for several reasons, including the security and diversification of energy supply, environmental protection and social and economic cohesion. The Eu Council's decision of 9 March 2007 points towards increasing renewable penetration to 20% of total primary energy supply by 2020 (binding target). There are both costs and benefits associated with the achievement of such an ambitious target. For renewable technologies, the industrial cost is often higher compared to other energy sources. however, due to learning curve effects and market diffusion, technology related costs are coming down considerably. In some cases, when the external costs are taken into account by the price system, renewable can now be close to competitive with fossil fuels. With particular reference to renewable electricity in Italy, its development is often hampered by burdensome and time consuming authorisation procedures with the consequence of a high mortality rate for the investments in the sector, leading to increased costs for the project management. Therefore, in these projects an important cost factor is the high cost of capital due to risk. The analysis of the various renewables' support mechanisms currently in place in the E U shows that some types of incentive have proven to be more efficient than others in reducing the risk perception of investors and financing institutions, therefore making projects less expensive by reducing the cost of capital (both debt and equity). Therefore the focus here is on the electricity generation costs of some renewable technologies and on the costs related to the additional risk perceived by investors/lenders in the sector. The authors estimate the additional cost of capital which investors pay when operating in a risky environment. Some policy indications are finally given to reduce the non-technology related costs for a faster and more efficient growth

  11. Effect of wind energy system performance on optimal renewable energy model - an analysis

    International Nuclear Information System (INIS)

    The Optimal Renewable Energy Model (OREM) has been developed to determine the optimum level of renewable energy sources utilisation in India for the year 2020-21. The model aims at minimising cost/efficiency ratio and determines the optimum allocation of different renewable energy sources for various end-uses. The extent of social acceptance level, potential limit, demand and reliability will decide the renewable energy distribution pattern and are hence used as constraints in the model. In this paper, the performance and reliability of wind energy system and its effects on OREM model has been analysed. The demonstration windfarm (4 MW) which is situated in Muppandal, a village in the southern part of India, has been selected for the study. The windfarm has 20 wind turbine machines of 200 KW capacity . The average technical availability, real availability and capacity factor have been analysed from 1991 to 1995 and they are found to be 94.1%, 76.4% and 25.5% respectively. The reliability factor of wind energy systems is found to be 0.5 at 10,000 hours. The OREM model is analysed considering the above said factors for wind energy system, solar energy system and biomass energy systems. The model selects wind energy for pumping end-use to an extent of 0.3153 x1015 KJ. (Author)

  12. Unified System-Level Modeling of Intermittent Renewable Energy Sources and Energy Storage for Power System Operation

    DEFF Research Database (Denmark)

    Heussen, Kai; Koch, Stephan; Ulbig, Andreas;

    2011-01-01

    The system-level consideration of inter- mittent renewable energy sources and small-scale en- ergy storage in power systems remains a challenge as either type is incompatible with traditional operation concepts. Non-controllability and energy-constraints are still considered contingent cases in...... market-based operation. The design of operation strategies for up to 100 % renewable energy systems requires an explicit consideration of non-dispatchable generation and stor- age capacities, as well as the evaluation of operational performance in terms of energy eciency, reliability, environmental...... in power system operation. After introducing the modeling ap- proach, a case study is presented for illustration....

  13. Integrating Variable Renewable Energy into Power System Operations

    OpenAIRE

    Nikolakakis, Thomas; Chatopadhyay, Debabrata

    2015-01-01

    Wind and solar energy is a fast-growing share of the global energy mix. But integrating them into power-system operations requires significant adaptations to compensate for their variability. Solutions include increasing the amount of flexible generation within the system, combining, and dispersing variable resources to smooth aggregate output, expanding the transmission network, using sma...

  14. Qualitative modeling identifies IL-11 as a novel regulator in maintaining self-renewal in human pluripotent stem cells

    Directory of Open Access Journals (Sweden)

    Hedi ePeterson

    2013-10-01

    Full Text Available Pluripotency in human embryonic stem cells (hESCs and induced pluripotent stem cells (iPSCs is regulated by three transcription factors - OCT3/4, SOX2 and NANOG. To fully exploit the therapeutic potential of these cells it is essential to have a good mechanistic understanding of the maintenance of self-renewal and pluripotency. In this study, we demonstrate a powerful systems biology approach in which we first expand literature-based network encompassing the core regulators of pluripotency by assessing the behaviour of genes targeted by perturbation experiments. We focused our attention on highly regulated genes encoding cell surface and secreted proteins as these can be more easily manipulated by the use of inhibitors or recombinant proteins. Qualitative modeling based on combining boolean networks and in silico perturbation experiments were employed to identify novel pluripotency-regulating genes. We validated Interleukin-11 (IL-11 and demonstrate that this cytokine is a novel pluripotency-associated factor capable of supporting self-renewal in the absence of exogenously added bFGF in culture. To date, the various protocols for hESCs maintenance require supplementation with bFGF to activate the Activin/Nodal branch of the TGFβ signaling pathway. Additional evidence supporting our findings is that IL-11 belongs to the same protein family as LIF, which is known to be necessary for maintaining pluripotency in mouse but not in human ESCs. These cytokines operate through the same gp130 receptor which interacts with Janus kinases. Our finding might explain why mESCs are in a more naïve cell state compared to hESCs and how to convert primed hESCs back to the naïve state. Taken together, our integrative modeling approach has identified novel genes as putative candidates to be incorporated into the expansion of the current gene regulatory network responsible for inducing and maintaining pluripotency.

  15. The feasibility of synthetic fuels in renewable energy systems

    DEFF Research Database (Denmark)

    Ridjan, Iva; Mathiesen, Brian Vad; Connolly, David;

    2012-01-01

    . Nowadays, biofuels along with electricity are proposed as one of the main options for replacing fossil fuels in the transport sector. The main reasons for avoiding the direct usage of biomass, i.e. producing biomass derived fuels, are land use shortage, limited biomass availability, interference with food...... fuels, with a specific focus on solid oxide electrolyser cells combined with the recycling of CO2....

  16. The feasibility of synthetic fuels in renewable energy systems

    DEFF Research Database (Denmark)

    Ridjan, Iva; Mathiesen, Brian Vad; Connolly, D.;

    2013-01-01

    , biofuels along with electricity are proposed as one of the main options for replacing fossil fuels in the transport sector. The main reasons for avoiding the direct usage of biomass, i.e. producing biomass derived fuels, are land use shortages, limited biomass availability, interference with food supplies...... fuels, with a specific focus on solid oxide electrolyser cells (SOEC) combined with the recycling of CO2....

  17. The feasibility of synthetic fuels in renewable energy systems

    DEFF Research Database (Denmark)

    Ridjan, Iva; Mathiesen, Brian Vad; Connolly, David;

    . Nowadays, biofuels along with electricity are proposed as one of the main options for replacing fossil fuels in the transport sector. The main reasons for avoiding the direct usage of biomass, i.e. producing biomass derived fuels, are land use shortage, limited biomass availability, interference with food...... fuels, with a specific focus on solid oxide electrolyser cells combined with the recycling of CO2....

  18. Supercapacitor energy storage technology and its application in renewable energy power generation system

    Energy Technology Data Exchange (ETDEWEB)

    Wang Sibo [Inst. of Electrical Engineering, CAS, BJ (China); Graduate School of Chinese Academy Science, BJ (China); Wei Tongzhen; Qi Zhiping [Inst. of Electrical Engineering, CAS, BJ (China)

    2008-07-01

    Supercapacitor is an emerging technology in the field of energy storage systems that can offer higher power density than batteries and higher energy density over traditional capacitors. Supercapacitor will become an attractive power solution to an increasing number of applications, such as renewable energy power generation, transportation, power system and many others, because of its advantages which include high charge/discharge current capability, very high efficiency, wide temperature range, etc. In this paper, the advantages and disadvantages of supercapacitor are discussed and some critical technologies for designing supercapacitor energy storage system are presented in detail. Finally, the role of the supercapacitor in renewable energy power system is discussed and a supercapacitor based uninterrupted power system (UPS) for the wind turbine pitch systems is presented as a design example. (orig.)

  19. The design of Smart Energy Systems for 100% renewable energy and transport solutions

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Lund, Henrik; Connolly, David;

    2013-01-01

    In this paper we launch the design of Smart Energy Systems through the 100% renewable energy system analyses and research behind the CEESA research project. The transition from fossil fuels towards the integration of more and more renewable energy requires rethinking and redesign of the energy...... system. Traditionally a lot of focus internationally is put on the electricity sector to solve the integration puzzle focusing on electricity storage technologies e.g. batteries, hydrogen storage and on (electricity) smart grids. In Smart Energy Systems the focus is integration of the electricity......, heating and transport sectors, and on using the flexibility in demands and various short term and longer term storage in the different sectors. Such a redesign also entails that the Smart Energy System is comprised of a number of smart grid infrastructures for different sectors in the energy system, i...

  20. Control system renewal for efficient operation in RIKEN 18 GHz electron cyclotron resonance ion source

    Science.gov (United States)

    Uchiyama, A.; Ozeki, K.; Higurashi, Y.; Kidera, M.; Komiyama, M.; Nakagawa, T.

    2016-02-01

    A RIKEN 18 GHz electron cyclotron resonance ion source (18 GHz ECRIS) is used as an external ion source at the Radioactive Ion Beam Factory (RIBF) accelerator complex to produce an intense beam of medium-mass heavy ions (e.g., Ca and Ar). In most components that comprise the RIBF, the control systems (CSs) are integrated by the Experimental Physics and Industrial Control System (EPICS). On the other hand, a non-EPICS-based system has hardwired controllers, and it is used in the 18 GHz ECRIS CS as an independent system. In terms of efficient and effective operation, the 18 GHz ECRIS CS as well as the RIBF CS should be renewed using EPICS. Therefore, we constructed an 18 GHz ECRIS CS by using programmable logic controllers with embedded EPICS technology. In the renewed system, an operational log system was developed as a new feature, for supporting of the 18 GHz ECRIS operation.

  1. Control system renewal for efficient operation in RIKEN 18 GHz electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Uchiyama, A., E-mail: a-uchi@riken.jp; Ozeki, K.; Higurashi, Y.; Kidera, M.; Komiyama, M.; Nakagawa, T. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2016-02-15

    A RIKEN 18 GHz electron cyclotron resonance ion source (18 GHz ECRIS) is used as an external ion source at the Radioactive Ion Beam Factory (RIBF) accelerator complex to produce an intense beam of medium-mass heavy ions (e.g., Ca and Ar). In most components that comprise the RIBF, the control systems (CSs) are integrated by the Experimental Physics and Industrial Control System (EPICS). On the other hand, a non-EPICS-based system has hardwired controllers, and it is used in the 18 GHz ECRIS CS as an independent system. In terms of efficient and effective operation, the 18 GHz ECRIS CS as well as the RIBF CS should be renewed using EPICS. Therefore, we constructed an 18 GHz ECRIS CS by using programmable logic controllers with embedded EPICS technology. In the renewed system, an operational log system was developed as a new feature, for supporting of the 18 GHz ECRIS operation.

  2. Control system renewal for efficient operation in RIKEN 18 GHz electron cyclotron resonance ion source

    International Nuclear Information System (INIS)

    A RIKEN 18 GHz electron cyclotron resonance ion source (18 GHz ECRIS) is used as an external ion source at the Radioactive Ion Beam Factory (RIBF) accelerator complex to produce an intense beam of medium-mass heavy ions (e.g., Ca and Ar). In most components that comprise the RIBF, the control systems (CSs) are integrated by the Experimental Physics and Industrial Control System (EPICS). On the other hand, a non-EPICS-based system has hardwired controllers, and it is used in the 18 GHz ECRIS CS as an independent system. In terms of efficient and effective operation, the 18 GHz ECRIS CS as well as the RIBF CS should be renewed using EPICS. Therefore, we constructed an 18 GHz ECRIS CS by using programmable logic controllers with embedded EPICS technology. In the renewed system, an operational log system was developed as a new feature, for supporting of the 18 GHz ECRIS operation

  3. A Robust Synchronization to Enhance the Power Quality of Renewable Energy Systems

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

    2015-01-01

    The increasing penetration of renewable energy sources (RESs) in the power grid requires high-quality power injection under various grid conditions. The synchronization method, usually a phase-locked loop (PLL) algorithm, is directly affecting the response of the grid-side converter of the RES...... response of the proposed PLL is validated, and the effect of the proposed synchronization on the performance of the grid-connected renewable energy system is investigated. This investigation proves that the robust, accurate, and dynamic response of the new PLL can enhance the quality of the injected power...

  4. Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using Geographic Information Systems

    Energy Technology Data Exchange (ETDEWEB)

    Heimiller, D.; Haase, S.; Melius, J.

    2013-05-01

    This report summarizes results of geographic information system screening for solar and wind potential at select Bureau of Reclamation lands in the western United States. The study included both utility-scale and facility-scale potential. This study supplements information in the report titled Renewable Energy Assessment for the Bureau of Reclamation: Final Report.

  5. Redesign Electricity Market for the Next Generation Power System of Renewable Energy and Distributed Storage Technologies

    DEFF Research Database (Denmark)

    Feng, Donghan; Xu, Zhao; Østergaard, Jacob

    2010-01-01

    This paper proposes a stochastic time-series based method to simulate the volatility of intermittent renewable generation and distributed storage devices along timeline. The proposed method can calculate the optimal timeline for different electricity markets and power systems. In practice, the...

  6. Transmission Needs In A Fully Renewable Pan-European Electricity System

    DEFF Research Database (Denmark)

    Rodriguez, Rolando A.; Bruun Andresen, Gorm; Becker, Sarah;

    2012-01-01

    Based on high-resolution weather and electrical load data, the transmission needs for a fully renewable pan-European electricity system are determined. The ideal cross-border transmission capacities turn out to be a factor 10 larger than those of today. A reduction of cross-border transmission...

  7. Overview of Power Generation Sector of Bangladesh and Proposed Grid Connected Hybrid Renewable Energy System

    Directory of Open Access Journals (Sweden)

    Md. Raju Ahmed

    2014-11-01

    Full Text Available Electricity is the most usable form of energy, and one of the most crucial strategic issues for the sustainable development of a country. The projection of demand of electricity is an integral part of the planning process. Severe power crisis compelled the government to enter into contractual agreements for high-cost temporary solution such as rental power and small IPPS, on an emergency basis, most of these are diesel or liquid-fuel based. Load shading is an acute problem for the country. The country is confronting a simultaneous shortage of electricity. However, the country has substantial amount of renewable energy resources. The overview of power generation section of Bangladesh is presented; the potentiality of renewable energy sources in Bangladesh is discussed. Finally, a grid connected hybrid renewable energy system is proposed to overcome the problem of power crisis using sustainable clean energy at rural area.

  8. Renewability and emergy footprint at different spatial scales for innovative food systems in Europe

    DEFF Research Database (Denmark)

    Wright, Christina; Østergård, Hanne

    2016-01-01

    ,reduced use of resources, nutrient cycling and local sales. The question is whether this type of food systemmay be considered sustainable from a resource use point of view measured as resource use efficiencyby means of unit emergy value (UEV), renewability (Ron-siteand Rglobal), direct and indirect......Food production is increasingly being challenged by limited resources of energy and land as well as bygrowing demand for food. In a future with less availability of fossil fuels, land area will become veryimportant for capturing the flow-limited renewable resources. Emergy assessment has been...... applied tocalculate scale dependent indicators, which account for the land area needed, if agricultural systems wereto be supported solely on renewable sources. These indicators are designated emergy footprints (EmFs)and expand the concept of support area defined previously in emergy accounting. The Em...

  9. Strategic Renewal of Activity Systems : An Interdependency Perspective

    OpenAIRE

    Albert, Daniel

    2013-01-01

    A growing literature stream conceptualizes organizations, their strategy, and business models as complex systems of interdependent activity choices. Accordingly, firms have to make decisions about which activities to engage in and to what extent. Choices made are interdependent with one another and thereby influence whether the system as a whole is internally consistent and fits its environment. The interdependencies among activity choices are found to be central to understanding sources of c...

  10. Empowering Variable Renewables - Options for Flexible Electricity Systems

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, Hugo [Renewable Energy Unit, International Energy Agency, Paris (France)

    2008-07-01

    A flexible electricity system is one that can respond reliably, and rapidly, to large fluctuations in supply and demand. Flexibility is already present in all power systems, in order to manage fluctuations in demand, and it is crucial for high performance and economic and reliable operation. This paper looks at measures to increase flexibility. but careful cost/benefit analysis is essential, and specific national and regional circumstances will influence the choice of option(s).

  11. Self-renewing Pten-/- TP53-/- protospheres produce metastatic adenocarcinoma cell lines with multipotent progenitor activity.

    Directory of Open Access Journals (Sweden)

    Wassim Abou-Kheir

    Full Text Available Prostate cancers of luminal adenocarcinoma histology display a range of clinical behaviors. Although most prostate cancers are slow-growing and indolent, a proportion is aggressive, developing metastasis and resistance to androgen deprivation treatment. One hypothesis is that a portion of aggressive cancers initiate from stem-like, androgen-independent tumor-propagating cells. Here we demonstrate the in vitro creation of a mouse cell line, selected for growth as self-renewing stem/progenitor cells, which manifests many in vivo properties of aggressive prostate cancer. Normal mouse prostate epithelium containing floxed Pten and TP53 alleles was subjected to CRE-mediated deletion in vitro followed by serial propagation as protospheres. A polyclonal cell line was established from dissociated protospheres and subsequently a clonal daughter line was derived. Both lines demonstrate a mature luminal phenotype in vitro. The established lines contain a stable minor population of progenitor cells with protosphere-forming ability and multi-lineage differentiation capacity. Both lines formed orthotopic adenocarcinoma tumors with metastatic potential to lung. Intracardiac inoculation resulted in brain and lung metastasis, while intra-tibial injection induced osteoblastic bone formation, recapitulating the bone metastatic phenotype of human prostate cancer. The cells showed androgen receptor dependent growth in vitro. Importantly, in vivo, the deprivation of androgens from established orthotopic tumors resulted in tumor regression and eventually castration-resistant growth. These data suggest that transformed prostate progenitor cells preferentially differentiate toward luminal cells and recapitulate many characteristics of the human disease.

  12. Renewing the Future: Social Innovation Systems, Sector Shift, and Innoweave

    Directory of Open Access Journals (Sweden)

    Stephen Huddart

    2012-07-01

    Full Text Available Against a backdrop of various “occupy” movements signifying civic dissatisfaction with the social contract, and in an era of fiscal restraint affecting governments and communities in many parts of the world, we need new and more effective ways to address complex social challenges. While continuous innovation is commonly understood to be a source of growth, productivity improvement, and competitive advantage in the technology and manufacturing sectors, the author’s focus is on social innovation systems, designed to replace maladaptive institutions and obsolete policy frameworks with novel and disruptive means for improving outcomes on issues such as population health and climate change. This article proposes a definition of such systems, and examines how system-level tools including impact investing, open data platforms, and “change labs” are fostering collaboration among the private, public, and community sectors. We argue that a key priority at this time is to make these and other tools and processes for social innovation available to community organizations and their government and business partners everywhere, in a manner that allows for continuous cycles of implementation and learning. The author describes one such project currently being developed in Canada by Social Innovation Generation and other partners, called Innoweave. Innoweave is a technology-enabled social innovation system for sharing the tools and processes of social innovation with the community sector. The article concludes with a call for multi-sectoral participation in social innovation systems as an investment in society’s adaptive capacity and future wellbeing.

  13. A technical and economic analysis of one potential pathway to a 100% renewable energy system

    Directory of Open Access Journals (Sweden)

    David Connolly

    2014-02-01

    Full Text Available This paper outlines how an existing energy system can be transformed into a 100% renewable energy system. The transition is divided into a number of key stages which reflect key radical technological changes on the supply side of the energy system. Ireland is used as a case study,but in reality this reflects many typical energy systems today which use power plants for electricity, individual boilers for heat, and oil for transport. The seven stages analysed are 1 reference, 2 introduction of district heating, 3 installation of small and large-scale heat pumps,4 reducing grid regulation requirements, 5 adding flexible electricity demands and electric vehicles, 6 producing synthetic methanol/DME for transport, and finally 7 using synthetic gas to replace the remaining fossil fuels. For each stage, the technical and economic performance of the energy system is calculated. The results indicate that a 100% renewable energy system can provide the same end-user energy demands as today’s energy system and at the same price. Electricity will be the backbone of the energy system, but the flexibility in today’s electricity sector will be transferred from the supply side of the demand side in the future. Similarly, due to changes in the type of spending required in a 100% renewable energy system, this scenario will result in the creation of 100,000 additional jobs in Ireland compared to an energy system like today’s. These results are significant since they indicate that the transition to a 100% renewable energy system can begin today, without increasing the cost of energy in the short- or long-term, if the costs currently forecasted for 2050 become a reality.

  14. Variable Renewable Generation can Provide Balancing Control to the Electric Power System (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2013-09-01

    As wind and solar plants become more common in the electric power system, they may be called on to provide grid support services to help maintain system reliability. For example, through the use of inertial response, primary frequency response, and automatic generation control (also called secondary frequency response), wind power can provide assistance in balancing the generation and load on the system. These active power (i.e., real power) control services have the potential to assist the electric power system in times of disturbances and during normal conditions while also potentially providing economic value to consumers and variable renewable generation owners. This one-page, two-sided fact sheet discusses the grid-friendly support and benefits renewables can provide to the electric power system.

  15. Transmission topologies for the integration of renewable power into the electricity systems of North Africa

    International Nuclear Information System (INIS)

    A cost-minimizing electricity market model was used to explore optimized infrastructures for the integration of renewable energies in interconnected North African power systems until 2030. The results show that the five countries Morocco, Algeria, Tunisia, Libya and Egypt could together achieve significant economic benefits, reaching up to €3.4 billion, if they increase power system integration, build interconnectors and cooperate on joint utilization of their generation assets. Net electricity exports out of North Africa to Europe or Eastern Mediterranean regions, however, were not observed in the regime of integrated electricity markets until 2030, and could only be realized by much higher levels of renewable energy penetration than currently foreseen by North African governments. - Highlights: • Market model to optimize North Africa's generation and transmission infrastructures until 2030. • Simulations consider existing interconnectors, power plant inventories, as well as national renewable goals. • Savings of up to €3.4 billion can be realized by more cooperation and integrated system planning. • No electricity exports to Europe in a competitive market framework, except for very high renewable penetrations

  16. Development and analysis of a new renewable energy-based multi-generation system

    International Nuclear Information System (INIS)

    A renewable energy-based multi-generation system is developed and studied energetically and exergetically. Two renewable sources of energy, biomass and geothermal, are combined to deliver five useful outputs for residential applications. The energy products from biomass sources are used to drive an organic Rankine cycle and a vapour absorption chiller, and further used to dry the wet material in an industrial dryer. A double flash system is used in the geothermal power cycle, which includes a multistage steam turbine. Outlet water flows from the separators and the steam turbine are used to heat water used in households. Liquefied gas is produced through the Linde Hampson liquefaction cycle, in which the compressor is directly coupled to organic Rankine cycle turbine. The energy efficiency of the system is found to be 56.5% and the exergy efficiency 20.3%. The largest exergy destructions are found to occur in both combustion chamber and boiler. The variations in exergy efficiencies and exergy destructions for the system components are determined with respect to changes in the reference-environment temperature and other major system parameters. - Highlights: • A new renewable energy-based multi-generation system is developed and studied. • Biomass and geothermal sources are combined with organic Rankine cycle. • Five outputs, namely electricity, hot water, cooling, liquefied gas and drying air are produced by the present system. • Energy and exergy analyses of developed system are carried out. • Advantages of multi-generation over single generation are illustrated

  17. C8orf4 negatively regulates self-renewal of liver cancer stem cells via suppression of NOTCH2 signalling

    OpenAIRE

    Zhu, Pingping; Wang, Yanying; Du, Ying; He, Lei; Huang, Guanling; Zhang, Geng; Yan, Xinlong; Fan, Zusen

    2015-01-01

    Liver cancer stem cells (CSCs) harbour self-renewal and differentiation properties, accounting for chemotherapy resistance and recurrence. However, the molecular mechanisms to sustain liver CSCs remain largely unknown. In this study, based on analysis of several hepatocellular carcinoma (HCC) transcriptome datasets and our experimental data, we find that C8orf4 is weakly expressed in HCC tumours and liver CSCs. C8orf4 attenuates the self-renewal capacity of liver CSCs and tumour propagation. ...

  18. Stability Control of Renewable Energy Sources in Distribution Systems

    Czech Academy of Sciences Publication Activity Database

    Tlustý, J.; Müller, Z.; Valouch, Viktor

    Eilat: IEEE, 2010, 000277-000281. ISBN 978-1-4244-8680-9. [2010 IEEE Convention of Electrical and Electronics Engineers in Israel /26./. Eilat (IL), 17.11.2010-20.11.2010] R&D Projects: GA AV ČR IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : stability * distributed generation * globally penetrated system Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  19. In-situ rehabilitation cleans, lines, and renews pipe systems

    International Nuclear Information System (INIS)

    This article discusses how, in the past five years, developments in coating and lining material technology have found their way into pipe line application and have yielded successful results. The thick film, high solids material often used to repair tanks, vessels and offshore structures has now been adapted for existing pipe lines. One of the most promising of these systems in successful service is an epoxy, high solids (95%) material originally developed for nuclear service as a lining for reactor containment vessels

  20. An Overview on Energy Storage Options for Renewable Energy Systems

    OpenAIRE

    Ajay Sharma

    2014-01-01

    Developing technology to store electrical energy so it can be available to meet demand whenever needed would represent a major breakthrough in electricity distribution. Helping to try and meet this goal, electricity storage devices can manage the amount of power required to supply customers at times when need is greatest, which is during peak load. This paper focuses on four storage technologies that can be used as storage for wind energy conversion system. For each storage te...

  1. Industrial Scale Energy Systems Integration; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Mark

    2015-07-28

    The industrial sector consumes 25% of the total energy in the U.S. and produces 18% of the greenhouse gas (GHG) emissions. Energy Systems Integration (ESI) opportunities can reduce those values and increase the profitability of that sector. This presentation outlines several options. Combined heat and power (CHP) is an option that is available today for many applications. In some cases, it can be extended to trigeneration by adding absorbtion cooling. Demand response is another option in use by the industrial sector - in 2012, industry provided 47% of demand response capacity. A longer term option that combines the benefits of CHP with those of demand response is hybrid energy systems (HESs). Two possible HESs are described and development implications discussed. extended to trigeneration by adding absorbtion cooling. Demand response is another option in use by the industrial sector - in 2012, industry provided 47% of demand response capacity. A longer term option that combines the benefits of CHP with those of demand response is hybrid energy systems (HESs). Two possible HESs are described and development implications discussed.

  2. DC Distributed Power Systems. Analysis, Design and Control for a Renewable Energy System

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Per

    2002-12-01

    Renewable energy systems are likely to become wide spread in the future due to environmental demands. As a consequence of the dispersed nature of renewable energy systems, this implies that there will be a distributed generation of electric power. Since most of the distributed electrical energy sources do not provide their electric power at line frequency and voltage, a DC bus is a useful common connection for several such sources. Due to the differences in output voltage among the sources, depending on both the type of source and their actual operating point, the sources are connected to the DC power system via power electronic converters. The intention behind the presented work is not to replace the existing AC power system, but to include local DC power systems. The AC and DC power systems are connected at some points in the network. The renewable energy sources are weak compared to the present hydro power and nuclear power plants, resulting in a need of power conditioning before the renewable energy is fed to the transmission lines. The benefit of such an approach is that power conditioning is applied on a central level, i.e. at the interface between the AC and DC power systems. The thesis starts with an overview of related work. Present DC transmission systems are discussed and investigated in simulations. Then, different methods for load sharing and voltage control are discussed. Especially, the voltage droop control scheme is examined thoroughly. Since the droop control method does not require any high-speed communication between sources and loads, this is considered the most suitable for DC distributed power systems. The voltage feed back design of the controller also results in a specification of the DC bus capacitors (equivalents to DC link capacitors of single converters) needed for filtering. If the converters in the DC distribution system are equipped with capacitors selected from this design criterion and if the DC bus impedance is neglected, the

  3. DC Distributed Power Systems. Analysis, Design and Control for a Renewable Energy System

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Per

    2002-12-01

    Renewable energy systems are likely to become wide spread in the future due to environmental demands. As a consequence of the dispersed nature of renewable energy systems, this implies that there will be a distributed generation of electric power. Since most of the distributed electrical energy sources do not provide their electric power at line frequency and voltage, a DC bus is a useful common connection for several such sources. Due to the differences in output voltage among the sources, depending on both the type of source and their actual operating point, the sources are connected to the DC power system via power electronic converters. The intention behind the presented work is not to replace the existing AC power system, but to include local DC power systems. The AC and DC power systems are connected at some points in the network. The renewable energy sources are weak compared to the present hydro power and nuclear power plants, resulting in a need of power conditioning before the renewable energy is fed to the transmission lines. The benefit of such an approach is that power conditioning is applied on a central level, i.e. at the interface between the AC and DC power systems. The thesis starts with an overview of related work. Present DC transmission systems are discussed and investigated in simulations. Then, different methods for load sharing and voltage control are discussed. Especially, the voltage droop control scheme is examined thoroughly. Since the droop control method does not require any high-speed communication between sources and loads, this is considered the most suitable for DC distributed power systems. The voltage feed back design of the controller also results in a specification of the DC bus capacitors (equivalents to DC link capacitors of single converters) needed for filtering. If the converters in the DC distribution system are equipped with capacitors selected from this design criterion and if the DC bus impedance is neglected, the

  4. Dynamic heterogeneity as a strategy of stem cell self-renewal.

    Science.gov (United States)

    Greulich, Philip; Simons, Benjamin D

    2016-07-01

    To maintain cycling adult tissue in homeostasis the balance between proliferation and differentiation of stem cells needs to be precisely regulated. To investigate how stem cells achieve perfect self-renewal, emphasis has been placed on models in which stem cells progress sequentially through a one-way proliferative hierarchy. However, investigations of tissue regeneration have revealed a surprising degree of flexibility, with cells normally committed to differentiation able to recover stem cell competence following injury. Here, we investigate whether the reversible transfer of cells between states poised for proliferation or differentiation may provide a viable mechanism for a heterogeneous stem cell population to maintain homeostasis even under normal physiological conditions. By addressing the clonal dynamics, we show that such models of "dynamic heterogeneity" may be equally capable of describing the results of recent lineage tracing assays involving epithelial tissues. Moreover, together with competition for limited niche access, such models may provide a mechanism to render tissue homeostasis robust. In particular, in 2D epithelial layers, we show that the mechanism of dynamic heterogeneity avoids some pathological dependencies that undermine models based on a hierarchical stem/progenitor organization. PMID:27313213

  5. Gab2 promotes hematopoietic stem cell maintenance and self-renewal synergistically with STAT5.

    Directory of Open Access Journals (Sweden)

    Geqiang Li

    Full Text Available BACKGROUND: Grb2-associated binding (Gab adapter proteins play major roles in coordinating signaling downstream of hematopoietic cytokine receptors. In hematopoietic cells, Gab2 can modulate phosphatidylinositol-3 kinase and mitogen associated protein kinase activities and regulate the long-term multilineage competitive repopulating activity of hematopoietic stem cells (HSCs. Gab2 may also act in a linear pathway upstream or downstream of signal transducer and activator of transcription-5 (STAT5, a major positive regulator of HSC function. Therefore, we aimed to determine whether Gab2 and STAT5 function in hematopoiesis in a redundant or non-redundant manner. METHODOLOGY/PRINCIPAL FINDINGS: To do this we generated Gab2 mutant mice with heterozygous and homozygous deletions of STAT5. In heterozygous STAT5 mutant mice, deficiencies in HSC/multipotent progenitors were reflected by decreased long-term repopulating activity. This reduction in repopulation function was mirrored in the reduced growth response to early-acting cytokines from sorted double mutant c-Kit(+Lin(-Sca-1(+ (KLS cells. Importantly, in non-ablated newborn mice, the host steady-state engraftment ability was impaired by loss of Gab2 in heterozygous STAT5 mutant background. Fetal liver cells isolated from homozygous STAT5 mutant mice lacking Gab2 showed significant reduction in HSC number (KLS CD150(+CD48(-, reduced HSC survival, and dramatic loss of self-renewal potential as measured by serial transplantation. CONCLUSIONS/SIGNIFICANCE: These data demonstrate new functions for Gab2 in hematopoiesis in a manner that is non-redundant with STAT5. Furthermore, important synergy between STAT5 and Gab2 was observed in HSC self-renewal, which might be exploited to optimize stem cell-based therapeutics.

  6. Performance Analyses of Renewable and Fuel Power Supply Systems for Different Base Station Sites

    Directory of Open Access Journals (Sweden)

    Josip Lorincz

    2014-11-01

    Full Text Available Base station sites (BSSs powered with renewable energy sources have gained the attention of cellular operators during the last few years. This is because such “green” BSSs impose significant reductions in the operational expenditures (OPEX of telecom operators due to the possibility of on-site renewable energy harvesting. In this paper, the green BSSs power supply system parameters detected through remote and centralized real time sensing are presented. An implemented sensing system based on a wireless sensor network enables reliable collection and post-processing analyses of many parameters, such as: total charging/discharging current of power supply system, battery voltage and temperature, wind speed, etc. As an example, yearly sensing results for three different BSS configurations powered by solar and/or wind energy are discussed in terms of renewable energy supply (RES system performance. In the case of powering those BSS with standalone systems based on a fuel generator, the fuel consumption models expressing interdependence among the generator load and fuel consumption are proposed. This has allowed energy-efficiency comparison of the fuel powered and RES systems, which is presented in terms of the OPEX and carbon dioxide (CO2 reductions. Additionally, approaches based on different BSS air-conditioning systems and the on/off regulation of a daily fuel generator activity are proposed and validated in terms of energy and capital expenditure (CAPEX savings.

  7. Advancing System Flexibility for High Penetration Renewable Integration

    Energy Technology Data Exchange (ETDEWEB)

    Milligan, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Frew, Bethany [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhou, Ella [National Renewable Energy Lab. (NREL), Golden, CO (United States); Arent, Douglas J. [Joint Inst. for Strategic Energy Analysis, Golden, CO (United States)

    2015-10-01

    This report summarizes some of the issues discussed during the engagement on power system flexibility. By design, the focus is on flexibility options used in the United States. Exploration of whether and how U.S. experiences can inform Chinese energy planning will be part of the continuing project, and will benefit from the knowledge base provided by this report. We believe the initial stage of collaboration represented in this report has successfully started a process of mutual understanding, helping Chinese researchers to begin evaluating how lessons learned in other countries might translate to China's unique geographic, economic, social, and political contexts.

  8. Orphan nuclear receptor TLX activates Wnt/β-catenin signalling to stimulate neural stem cell proliferation and self-renewal

    OpenAIRE

    Qu, Qiuhao; Sun, Guoqiang; Li, Wenwu; Yang, Su; Ye, Peng; Zhao, Chunnian; Yu, Ruth T.; Gage, Fred H; Evans, Ronald M; Shi, Yanhong

    2009-01-01

    The nuclear receptor TLX (also known as NR2E1) is essential for adult neural stem cell self-renewal; however, the molecular mechanisms involved remain elusive. Here we show that TLX activates the canonical Wnt/β-catenin pathway in adult mouse neural stem cells. Furthermore, we demonstrate that Wnt/β-catenin signalling is important in the proliferation and self-renewal of adult neural stem cells in the presence of epidermal growth factor and fibroblast growth factor. Wnt7a and active β-catenin...

  9. Technical evaluation of two 6-kW mono-Si photovoltaic systems at the National Renewable Energy Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Dyk, E.E. van; Strand, T.; Hansen, R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    This paper presents an analysis of performance data on the two 6-kW{sub ac} grid-connected photovoltaic systems at the National Renewable Energy Laboratory (NREL). The performance parameters analyzed include dc and ac power, aperture efficiency, energy, capacity factor and performance index which are compared to plane-of-array irradiance, ambient temperature, and back-of-module temperature as a function of time, either daily or monthly. Power ratings of the systems were also obtained for data corresponding to different test conditions. This study has shown, in addition to expected seasonal trends, that system monitoring is a valuable tool in assessing performance and detecting faulty equipment. In addition, methods applied for this study may be used to evaluate and compare systems employing different cell technologies.

  10. Analysis of essential pathways for self-renewal in common marmoset embryonic stem cells

    Directory of Open Access Journals (Sweden)

    Takenobu Nii

    2014-01-01

    Full Text Available Common marmoset (CM is widely recognized as a useful non-human primate for disease modeling and preclinical studies. Thus, embryonic stem cells (ESCs derived from CM have potential as an appropriate cell source to test human regenerative medicine using human ESCs. CM ESCs have been established by us and other groups, and can be cultured in vitro. However, the growth factors and downstream pathways for self-renewal of CM ESCs are largely unknown. In this study, we found that basic fibroblast growth factor (bFGF rather than leukemia inhibitory factor (LIF promoted CM ESC self-renewal via the activation of phosphatidylinositol-3-kinase (PI3K-protein kinase B (AKT pathway on mouse embryonic fibroblast (MEF feeders. Moreover, bFGF and transforming growth factor β (TGFβ signaling pathways cooperatively maintained the undifferentiated state of CM ESCs under feeder-free condition. Our findings may improve the culture techniques of CM ESCs and facilitate their use as a preclinical experimental resource for human regenerative medicine.

  11. AGING MANAGMENT OF REACTOR COOLANT SYSTEM MECHANICAL COMPONENTS FOR LICENSE RENEWAL

    International Nuclear Information System (INIS)

    The reactor coolant system (RCS) mechanical components that require an aging management review for license renewal include the primary loop piping and associated connections to other support systems, reactor vessel, reactor vessel internals, pressurizer. steam generators, reactor coolant pumps, and all other inter-connected piping, pipe fittings, valves, and bolting. All major RCS components are located inside the reactor building. Based on the evaluation findings of recently submitted license renewal applications for pressurized water reactors, this paper presents the plant programs and/or activities proposed by the applicants to manage the effects of aging. These programs and/or activities provide reasonable assurance that the intended function(s) of these mechanical components will be maintained for the period of extended operation. The license renewal application includes identification of RCS subcomponents that are within the scope of license renewal and are vulnerable to age-related degradation when exposed to environmental and operational conditions. determination of the effects of aging on their intended safety functions. and implementation of the aging management programs and/or activities including both current and new programs. Industry-wide operating experience, including generic communication by the NRC, is part of the aging management review for the RCS components. In addition, this paper discusses time-limited aging analyses associated with neutron embrittlement of the reactor vessel beltline region and thermal fatigue

  12. The Drosophila BCL6 homolog Ken and Barbie promotes somatic stem cell self-renewal in the testis niche.

    Science.gov (United States)

    Issigonis, Melanie; Matunis, Erika

    2012-08-15

    Stem cells sustain tissue regeneration by their remarkable ability to replenish the stem cell pool and to generate differentiating progeny. Signals from local microenvironments, or niches, control stem cell behavior. In the Drosophila testis, a group of somatic support cells called the hub creates a stem cell niche by locally activating the Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) pathway in two adjacent types of stem cells: germline stem cells (GSCs) and somatic cyst stem cells (CySCs). Here, we find that ken and barbie (ken) is autonomously required for the self-renewal of CySCs but not GSCs. Furthermore, Ken misexpression in the CySC lineage induces the cell-autonomous self-renewal of somatic cells as well as the nonautonomous self-renewal of germ cells outside the niche. Thus, Ken, like Stat92E and its targets ZFH1 (Leatherman and Dinardo, 2008) and Chinmo (Flaherty et al., 2010), is necessary and sufficient for CySC renewal. However, ken is not a JAK-STAT target in the testis, but instead acts in parallel to Stat92E to ensure CySC self-renewal. Ken represses a subset of Stat92E targets in the embryo (Arbouzova et al., 2006) suggesting that Ken maintains CySCs by repressing differentiation factors. In support of this hypothesis, we find that the global JAK-STAT inhibitor Protein tyrosine phosphatase 61F (Ptp61F) is a JAK-STAT target in the testis that is repressed by Ken. Together, our work demonstrates that Ken has an important role in the inhibition of CySC differentiation. Studies of ken may inform our understanding of its vertebrate orthologue B-Cell Lymphoma 6 (BCL6) and how misregulation of this oncogene leads to human lymphomas. PMID:22580161

  13. A dynamic MOPSO algorithm for multiobjective optimal design of hybrid renewable energy systems

    OpenAIRE

    Sharafi, Masoud; Elmekkawy, Tarek Y.

    2014-01-01

    In this paper, a dynamic multiobjective particle swarm optimization (DMOPSO) method is presented for the optimal design of hybrid renewable energy systems (HRESs). The main goal of the design is to minimize simultaneously the total net present cost (NPC) of the system, unmet load, and fuel emission. A DMOPSO-simulation based approach has been used to approximate a worthy Pareto front (PF) to help decision makers in selecting an optimal configuration for an HRES. The proposed method is examine...

  14. Integration of Renewable Energy Sources in Future Power Systems: The Role of Storage

    OpenAIRE

    Weitemeyer, Stefan; Kleinhans, David; Vogt, Thomas; Agert, Carsten

    2014-01-01

    Integrating a high share of electricity from non-dispatchable Renewable Energy Sources in a power supply system is a challenging task. One option considered in many studies dealing with prospective power systems is the installation of storage devices to balance the fluctuations in power production. However, it is not yet clear how soon storage devices will be needed and how the integration process depends on different storage parameters. Using long-term solar and wind energy power production ...

  15. Renewable Energy Use in Smallholder Farming Systems: A Case Study in Tafresh Township of Iran

    OpenAIRE

    Hossein Shabanali Fami; Javad Ghasemi; Rahil Malekipoor; Parinaz Rashidi; Saeede Nazari; Arezoo Mirzaee

    2010-01-01

    This study was conducted to investigate use of renewable energy and materials in smallholder farming system of the Tafresh township of Iran. The population of the study consisted of 2,400 small farmers working in the smallholder farming systems of the area, in which 133 people were selected as sample using Cochran formula and simple random sampling technique. In order to gather the information, a questionnaire was developed for the study and validated by the judgment of the experts in agricul...

  16. The Realization of a Discrete-Time Deterministic Regulator for Energy Renewable Multivariable Systems

    OpenAIRE

    OBINABO, EDWIN CHUKWUDI; Okundamiya, M. S.

    2010-01-01

    This study proposes an optimal control law for a linear constant energy renewal multivariable system supplying power to protection and signaling circuits for switchgears and substation operations. The energy storage mechanism creates a control source that dictates the frequency of the pow er supply voltage. The entire analysis was based essentially on the use of a vector of inputs and outputs, and a matrix of operations characterizing the storage mechanism, assuming the system is both control...

  17. RESRO: A spatio-temporal model to optimise regional energy systems emphasising renewable energies

    OpenAIRE

    Gadocha S.; Hausl S.; Biberacher M.

    2012-01-01

    RESRO (Reference Energy System Regional Optimization) optimises the simultaneous fulfilment of the heat and power demand in regional energy systems. It is a mixed-integer program realised in the modelling language GAMS. The model handles information on geographically disaggregated data describing heat demand and renewable energy potentials (e.g. biomass, solar energy, ambient heat). Power demand is handled spatially aggregated in an hourly time resolution within 8 type days. The major idea is...

  18. Functional self-assembled lipidic systems derived from renewable resources

    Science.gov (United States)

    Silverman, Julian R.; Samateh, Malick; John, George

    2015-01-01

    Self-assembled lipidic amphiphile systems can create a variety of multi-functional soft materials with value-added properties. When employing natural reagents and following biocatalytic syntheses, self-assembling monomers may be inherently designed for degradation, making them potential alternatives to conventional and persistent polymers. By using non-covalent forces, self-assembled amphiphiles can form nanotubes, fibers, and other stimuli responsive architectures prime for further applied research and incorporation into commercial products. By viewing these lipid derivatives under a lens of green principles, there is the hope that in developing a structure–function relationship and functional smart materials that research may remain safe, economic, and efficient. PMID:26766923

  19. Advancing System Flexibility for High Penetration Renewable Integration (Chinese Translation)

    Energy Technology Data Exchange (ETDEWEB)

    Milligan, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Frew, Bethany [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhou, Ella [National Renewable Energy Lab. (NREL), Golden, CO (United States); Arent, Douglas J. [Joint Inst. for Strategic Energy Analysis, Golden, CO (United States)

    2015-10-01

    This is a Chinese translation of NREL/TP-6A20-64864. This report summarizes some of the issues discussed during the engagement on power system flexibility. By design, the focus is on flexibility options used in the United States. Exploration of whether and how U.S. experiences can inform Chinese energy planning will be part of the continuing project, and will benefit from the knowledge base provided by this report. We believe the initial stage of collaboration represented in this report has successfully started a process of mutual understanding, helping Chinese researchers to begin evaluating how lessons learned in other countries might translate to China's unique geographic, economic, social, and political contexts.

  20. SirT1—A Sensor for Monitoring Self-Renewal and Aging Process in Retinal Stem Cells

    Directory of Open Access Journals (Sweden)

    Chi-Hsien Peng

    2010-06-01

    Full Text Available Retinal stem cells bear potency of proliferation, self-renewal, and differentiation into many retinal cells. Utilizing appropriate sensors one can effectively detect the self-renewal and aging process abilities. Silencing information regulator (SirT1, a member of the sirtuin family, is a NAD-dependent histone deacetylase and an essential mediator for longevity in normal cells by calorie restriction. We firstly investigate the SirT1 mRNA expression in retinal stem cells from rats and 19 human eyes of different ages. Results revealed that SirT1 expression was significantly decreased in in vivo aged eyes, associated with poor self-renewal abilities. Additionally, SirT1 mRNA levels were dose-dependently increased in resveratrol- treated retinal stem cells. The expression of SirT1 on oxidative stress-induced damage was significantly decreased, negatively correlated with the level of intracellular reactive oxygen species production. Treatment with resveratrol could effectively further reduce oxidative stress induced by H2O2 treatment in retinal stem cells. Importantly, the anti-oxidant effects of resveratrol in H2O2-treated retinal stem cells were significantly abolished by knockdown of SirT1 expression (sh-SirT1. SirT1 expression provides a feasible sensor in assessing self-renewal and aging process in retinal stem cells. Resveratrol can prevent reactive oxygen species-induced damages via increased retinal SirT1 expression.

  1. Two major gate-keepers in the self-renewal of neural stem cells: Erk1/2 and PLCγ1 in FGFR signaling

    Directory of Open Access Journals (Sweden)

    Lee Jin-A

    2009-06-01

    Full Text Available Abstract Neural stem cells are undifferentiated precursor cells that proliferate, self-renew, and give rise to neuronal and glial lineages. Understanding the molecular mechanisms underlying their self-renewal is an important aspect in neural stem cell biology. The regulation mechanisms governing self-renewal of neural stem cells and the signaling pathways responsible for the proliferation and maintenance of adult stem cells remain largely unknown. In this issue of Molecular Brain [Ma DK et al. Molecular genetic analysis of FGFR1 signaling reveals distinct roles of MAPK and PLCγ1 activation for self-renewal of adult neural stem cells. Molecular Brain 2009, 2:16], characterized the different roles of MAPK and PLCγ1 in FGFR1 signaling in the self-renewal of neural stem cells. These novel findings provide insights into basic neural stem cell biology and clinical applications of potential stem-cell-based therapy.

  2. Differential effects on cell motility, embryonic stem cell self-renewal and senescence by diverse Src kinase family inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Tamm, Christoffer, E-mail: christoffer.tamm@imbim.uu.se; Galito, Sara Pijuan, E-mail: sara.pijuan@imbim.uu.se; Anneren, Cecilia, E-mail: cecilia.anneren@imbim.uu.se

    2012-02-15

    The Src family of non-receptor tyrosine kinases (SFKs) has been shown to play an intricate role in embryonic stem (ES) cell maintenance. In the present study we have focused on the underlying molecular mechanisms responsible for the vastly different effects induced by various commonly used SFK inhibitors. We show that several diverse cell types, including fibroblasts completely lacking SFKs, cannot undergo mitosis in response to SU6656 and that this is caused by an unselective inhibition of Aurora kinases. In contrast, PP2 and PD173952 block motility immediately upon exposure and forces cells to grow in dense colonies. The subsequent halt in proliferation of fibroblast and epithelial cells in the center of the colonies approximately 24 h post-treatment appears to be caused by cell-to-cell contact inhibition rather than a direct effect of SFK kinase inhibition. Interestingly, in addition to generating more homogenous and dense ES cell cultures, without any diverse effect on proliferation, PP2 and PD173652 also promote ES cell self-renewal by reducing the small amount of spontaneous differentiation typically observed under standard ES cell culture conditions. These effects could not be mirrored by the use of Gleevec, a potent inhibitor of c-Abl and PDGFR kinases that are also inhibited by PP2. -- Highlights: Black-Right-Pointing-Pointer SFK inhibitor SU6656 induces senescence in mouse ES cells. Black-Right-Pointing-Pointer SU6656 inhibits mitosis in a SFK-independent manner via cross-selectivity for Aurora kinases. Black-Right-Pointing-Pointer SFK inhibitor PP2 impairs cell motility in various cell lines, including mouse ES cells. Black-Right-Pointing-Pointer Ensuing impeded motility, PP2 inhibits proliferation of various cells lines except for mouse ES cells. Black-Right-Pointing-Pointer SFK inhibitors PP2 and PD173952 impede spontaneous differentiation in standard mouse ES culture maintenance.

  3. Differential effects on cell motility, embryonic stem cell self-renewal and senescence by diverse Src kinase family inhibitors

    International Nuclear Information System (INIS)

    The Src family of non-receptor tyrosine kinases (SFKs) has been shown to play an intricate role in embryonic stem (ES) cell maintenance. In the present study we have focused on the underlying molecular mechanisms responsible for the vastly different effects induced by various commonly used SFK inhibitors. We show that several diverse cell types, including fibroblasts completely lacking SFKs, cannot undergo mitosis in response to SU6656 and that this is caused by an unselective inhibition of Aurora kinases. In contrast, PP2 and PD173952 block motility immediately upon exposure and forces cells to grow in dense colonies. The subsequent halt in proliferation of fibroblast and epithelial cells in the center of the colonies approximately 24 h post-treatment appears to be caused by cell-to-cell contact inhibition rather than a direct effect of SFK kinase inhibition. Interestingly, in addition to generating more homogenous and dense ES cell cultures, without any diverse effect on proliferation, PP2 and PD173652 also promote ES cell self-renewal by reducing the small amount of spontaneous differentiation typically observed under standard ES cell culture conditions. These effects could not be mirrored by the use of Gleevec, a potent inhibitor of c-Abl and PDGFR kinases that are also inhibited by PP2. -- Highlights: ► SFK inhibitor SU6656 induces senescence in mouse ES cells. ► SU6656 inhibits mitosis in a SFK-independent manner via cross-selectivity for Aurora kinases. SFK inhibitor PP2 impairs cell motility in various cell lines, including mouse ES cells. ► Ensuing impeded motility, PP2 inhibits proliferation of various cells lines except for mouse ES cells. ► SFK inhibitors PP2 and PD173952 impede spontaneous differentiation in standard mouse ES culture maintenance.

  4. mir-300 promotes self-renewal and inhibits the differentiation of glioma stem-like cells

    KAUST Repository

    Zhang, Daming

    2014-01-28

    MicroRNAs (miRNAs) are small noncoding RNAs that have been critically implicated in several human cancers. miRNAs are thought to participate in various biological processes, including proliferation, cell cycle, apoptosis, and even the regulation of the stemness properties of cancer stem cells. In this study, we explore the potential role of miR-300 in glioma stem-like cells (GSLCs). We isolated GSLCs from glioma biopsy specimens and identified the stemness properties of the cells through neurosphere formation assays, multilineage differentiation ability analysis, and immunofluorescence analysis of glioma stem cell markers. We found that miR-300 is commonly upregulated in glioma tissues, and the expression of miR-300 was higher in GSLCs. The results of functional experiments demonstrated that miR-300 can enhance the self-renewal of GSLCs and reduce differentiation toward both astrocyte and neural fates. In addition, LZTS2 is a direct target of miR-300. In conclusion, our results demonstrate the critical role of miR-300 in GSLCs and its functions in LZTS2 inhibition and describe a new approach for the molecular regulation of tumor stem cells. © 2014 Springer Science+Business Media.

  5. Seasonal shifting of surplus renewable energy in a power system located in a cold region

    Directory of Open Access Journals (Sweden)

    Jorge Morel

    2014-10-01

    Full Text Available The Fukushima nuclear disaster in 2011 changed Japan's strategy for reducing CO2 emissions. The government is now placing more emphasis on the development of nonCO2-emitting distributed generation systems such as wind, solar, and tidal power to reduce greenhouse gas emissions and guarantee electricity supply in the case of a natural disaster. This paper proposes a strategy for the exploitation of wind, solar, and tidal resources in a cold region in Japan by utilizing surplus energy from the summer and spring during winter. It also aims to determine the most favorable energy mix of these renewable sources and storage system types. The study is performed by calculating hourly demand and renewable energy supply for the city in one year, which is based on actual data of demand, solar irradiation, wind speeds, and tidal current speeds. The costs of the components of the renewable power plants and storage systems are considered, and different proportions of generation outputs are evaluated with different types of storage systems. According to results, the configuration containing the hydrogen storage system using organic chemical hydride methylcyclohexane (OCHM is the most economical but is still more expensive than one using a conventional generation system. Moreover, we confirm that the cost of CO2 emissions is the key element for leveling the playing field between conventional and renewable generation from an economic perspective. The cost of CO2 emissions to public health as well as those costs related to the interruption of services during a catastrophe must be carefully calculated with other issues from conventional power projects to perform a precise comparative evaluation between both types of generation systems.

  6. Operating conditions of batteries in off-grid renewable energy systems

    DEFF Research Database (Denmark)

    Svoboda, V.; Wenzl, H.; Kaiser, R.;

    2007-01-01

    Operating conditions in off-grid renewable energy systems (RES) vary significantly in different applications and locations. To describe RES and the operating conditions of their components it is useful to define categories of similar operating conditions. Categories can also be used for lifetime...... considerations of RES components, for making recommendations and for analysing the properties and performance of a RES and its components. Categories support system designers and an economic analysis. This paper describes the process and the results of creating RES categories of similar operating conditions...... for batteries. Categories are defined in such a way that batteries belonging to the same category are subjected to similar operating conditions and a similar combination of stress factors. The results provide a comprehensive overview of battery operating conditions in existing off-grid renewable energy systems...

  7. A New Energy Management Technique for PV/Wind/Grid Renewable Energy System

    Directory of Open Access Journals (Sweden)

    Onur Ozdal Mengi

    2015-01-01

    Full Text Available An intelligent energy management system (IEMS for maintaining the energy sustainability in renewable energy systems (RES is introduced here. It consists of wind and photovoltaic (PV solar panels are established and used to test the proposed IEMS. Since the wind and solar sources are not reliable in terms of sustainability and power quality, a management system is required for supplying the load power demand. The power generated by RES is collected on a common DC bus as a renewable green power pool to be used for supplying power to loads. The renewable DC power bus is operated in a way that there is always a base power available for permanent loads. Then the additional power requirement is supplied from either wind or PV or both depending upon the availability of these power sources. The decision about operating these systems is given by an IEMS with fuzzy logic decision maker proposed in this study. Using the generated and required power information from the wind/PV and load sides, the fuzzy reasoning based IEMS determines the amount of power to be supplied from each or both sources. Besides, the IEMS tracks the maximum power operating point of the wind energy system.

  8. Hybrid renewable energy system application for electricity and heat supply of a residential building

    Directory of Open Access Journals (Sweden)

    Nakomčić-Smaragdakis Branka B.

    2016-01-01

    Full Text Available Renewable and distributed energy systems could provide a solution to the burning issue of reliable and clean supply of energy, having in mind current state and future predictions for population growth and fossil fuel scarcity. Hybrid renewable energy systems are novelty in Serbia and warrant further detailed research. The aim of this paper is to analyze the application of renewable energy sources(RES for electricity and heat supply of a typical household in Serbia, as well as the cost-effectiveness of the proposed system. The influence of feed-in tariff change on the value of the investment is analyzed. Small, grid-connected hybrid system (for energy supply of a standard household, consisting of geothermal heat pump for heating/cooling, solar photovoltaic panels and small wind turbine for power supply is analyzed as a case study. System analysis was conducted with the help of RETScreen software. Results of techno-economics analysis have shown that investing in geothermal heat pump and photovoltaic panels is cost-effective, while that is not the case with small wind turbine.

  9. A hybrid model for the optimum integration of renewable technologies in power generation systems

    International Nuclear Information System (INIS)

    The main purpose of this work is to assess the unavoidable increase in the cost of electricity of a generation system by the integration of the necessary renewable energy sources for power generation (RES-E) technologies in order for the European Union Member States to achieve their national RES energy target. The optimization model developed uses a genetic algorithm (GA) technique for the calculation of both the additional cost of electricity due to the penetration of RES-E technologies as well as the required RES-E levy in the electricity bills in order to fund this RES-E penetration. Also, the procedure enables the estimation of the optimum feed-in-tariff to be offered to future RES-E systems. Also, the overall cost increase in the electricity sector for the promotion of RES-E technologies, for the period 2010-2020, is analyzed taking into account factors, such as, the fuel avoidance cost, the carbon dioxide emissions avoidance cost, the conventional power system increased operation cost, etc. The overall results indicate that in the case of RES-E investments with internal rate of return (IRR) of 10% the cost of integration is higher, compared to RES-E investments with no profit, (i.e., IRR at 0%) by 0.3-0.5 Euro c/kWh (in real prices), depending on the RES-E penetration level. - Research Highlights: →Development of a hybrid optimization model for the integration of renewable technologies in power generation systems. →Estimation of the optimum feed-in-tariffs to be offered to future renewable systems. →Determination of the overall cost increase in the electricity sector for the promotion of renewable technologies. →Analyses taking into account fuel avoidance cost, the carbon dioxide emissions avoidance cost, the conventional power system increased operation cost, etc.

  10. Model documentation renewable fuels module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1995 Annual Energy Outlook (AEO95) forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. The RFM consists of six analytical submodules that represent each of the major renewable energy resources--wood, municipal solid waste (MSW), solar energy, wind energy, geothermal energy, and alcohol fuels. The RFM also reads in hydroelectric facility capacities and capacity factors from a data file for use by the NEMS Electricity Market Module (EMM). The purpose of the RFM is to define the technological, cost and resource size characteristics of renewable energy technologies. These characteristics are used to compute a levelized cost to be competed against other similarly derived costs from other energy sources and technologies. The competition of these energy sources over the NEMS time horizon determines the market penetration of these renewable energy technologies. The characteristics include available energy capacity, capital costs, fixed operating costs, variable operating costs, capacity factor, heat rate, construction lead time, and fuel product price.

  11. Model documentation: Renewable Fuels Module of the National Energy Modeling System

    Science.gov (United States)

    1994-04-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it related to the production of the 1994 Annual Energy Outlook (AEO94) forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. This documentation report serves two purposes. First, it is a reference document for model analysts, model users, and the public interested in the construction and application of the RFM. Second, it meets the legal requirement of the Energy Information Administration (EIA) to provide adequate documentation in support of its models. The RFM consists of six analytical submodules that represent each of the major renewable energy resources -- wood, municipal solid waste (MSW), solar energy, wind energy, geothermal energy, and alcohol fuels. Of these six, four are documented in the following chapters: municipal solid waste, wind, solar and biofuels. Geothermal and wood are not currently working components of NEMS. The purpose of the RFM is to define the technological and cost characteristics of renewable energy technologies, and to pass these characteristics to other NEMS modules for the determination of mid-term forecasted renewable energy demand.

  12. Model documentation renewable fuels module of the National Energy Modeling System

    Science.gov (United States)

    1995-06-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1995 Annual Energy Outlook (AEO95) forecasts. The report catalogs and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. The RFM consists of six analytical submodules that represent each of the major renewable energy resources -- wood, municipal solid waste (MSW), solar energy, wind energy, geothermal energy, and alcohol fuels. The RFM also reads in hydroelectric facility capacities and capacity factors from a data file for use by the NEMS Electricity Market Module (EMM). The purpose of the RFM is to define the technological, cost, and resource size characteristics of renewable energy technologies. These characteristics are used to compute a levelized cost to be competed against other similarly derived costs from other energy sources and technologies. The competition of these energy sources over the NEMS time horizon determines the market penetration of these renewable energy technologies. The characteristics include available energy capacity, capital costs, fixed operating costs, variable operating costs, capacity factor, heat rate, construction lead time, and fuel product price.

  13. Layered double hydroxide nanoparticles promote self-renewal of mouse embryonic stem cells through the PI3K signaling pathway

    Science.gov (United States)

    Wu, Youjun; Zhu, Rongrong; Zhou, Yang; Zhang, Jun; Wang, Wenrui; Sun, Xiaoyu; Wu, Xianzheng; Cheng, Liming; Zhang, Jing; Wang, Shilong

    2015-06-01

    Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles have shown promising applications in directing the stem cell fate. Herein, we investigated the cellular effects of layered double hydroxide nanoparticles (LDH NPs) on mouse ESCs (mESCs) and the associated molecular mechanisms. Mg-Al-LDH NPs with an average diameter of ~100 nm were prepared by hydrothermal methods. To determine the influences of LDH NPs on mESCs, cellular cytotoxicity, self-renewal, differentiation potential, and the possible signaling pathways were explored. Evaluation of cell viability, lactate dehydrogenase release, ROS generation and apoptosis demonstrated the low cytotoxicity of LDH NPs. The alkaline phosphatase activity and the expression of pluripotency genes in mESCs were examined, which indicated that exposure to LDH NPs could support self-renewal and inhibit spontaneous differentiation of mESCs under feeder-free culture conditions. The self-renewal promotion was further proved to be independent of the leukemia inhibitory factor (LIF). Furthermore, cells treated with LDH NPs maintained the potential to differentiate into all three germ layers both in vitro and in vivo through formation of embryoid bodies and teratomas. In addition, we observed that LDH NPs initiated the activation of the PI3K/Akt pathway, while treatment with the PI3K inhibitor LY294002 could block the effects of LDH NPs on mESCs. The results confirmed that the promotion of self-renewal by LDH NPs was associated with activation of the PI3K/Akt signaling pathway. Altogether, our studies identified a new role of LDH NPs in maintaining self-renewal of mouse ES cells which could potentially be applied in stem cell research.Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles

  14. GIS-based site selection methodology for hybrid renewable energy systems: A case study from western Turkey

    International Nuclear Information System (INIS)

    Highlights: ► We proposed a site selection methodology for renewable energy systems. ► Fuzzy logic and geographic information system tools are used. ► Alternative locations are evaluated in terms of economic and environmental criteria. - Abstract: Renewable energy sources are presently being considered as alternatives to fossil fuels, because they are perpetual, environmentally friendly, and release negligible amounts of greenhouse gases to the atmosphere while producing energy. A disadvantage of renewable energy systems, however, is that continuous energy generation is not possible by using only one type of renewable energy system, since renewable energy resources depend on climate and weather conditions. Two or more renewable energy systems can be integrated into a hybrid system to overcome this problem so that when one resource is not available, the other can continue producing energy. Another disadvantage of renewable energy sources is that they are not available at every geographic location. Their use is mostly advantageous at remote locations that often are of high ecological value. Thus, identification of preferable locations for renewable energy systems is a decision-making problem that requires evaluation of the potential of the resource together with economic and environmental limitations. This paper introduces a methodology for site selection of hybrid wind solar–PV renewable energy systems. First, environmental acceptability and economic feasibility objectives are identified through a comprehensive review of the literature, current Turkish laws and legislations, and interviews with the General Directorate of Electrical Power Resources Survey and Development Administration of Turkey. Second, viable locations in terms of environmental acceptability and economic feasibility are determined through a fuzzy decision-making procedure that uses ordered weighted averaging algorithm for aggregating multiple objectives. Then, priority sites are identified

  15. Power Quality Assessment in Small Scale Renewable Energy Sources Supplying Distribution Systems

    Directory of Open Access Journals (Sweden)

    Dario Zaninelli

    2013-01-01

    Full Text Available The impact of wind turbines and photovoltaic systems on network operation and power quality (harmonics, and voltage fluctuations is very important. The capability of the power system to absorb this perturbation is dependent on the fault level at the point of common coupling. The paper deals with power quality case studies conducted on existing renewable resources-based systems. Voltage fluctuations determined by a 0.65 MVA wind turbine are analyzed. The impact of photovoltaic systems on steady state voltage variations and current harmonics is investigated. The correlation between the generated power and the main power quality indices is highlighted.

  16. Solar cell concentrating system

    International Nuclear Information System (INIS)

    This study reviews fabrication techniques and testing facilities for different solar cells under concentration which have been developed and tested. It is also aimed to examine solar energy concentrators which are prospective candidates for photovoltaic concentrator systems. This may provide an impetus to the scientists working in the area of solar cell technology

  17. Use of Danish Heat Atlas and energy system models for exploring renewable energy scenarios

    DEFF Research Database (Denmark)

    Petrovic, Stefan; Karlsson, Kenneth Bernard

    2013-01-01

    reducing greenhouse gas emissions, increasing share of renewable energy and improving energy efficiency and (ii) Denmark’s 2050 goals of covering entire energy supply by renewable energy. Optimization and simulation energy system models are currently used in Denmark. The present paper tends to provide a...... comprehensive insight into the use of the Heat Atlas for Denmark in recent studies dealing with municipal strategic energy planning and main scientific papers addressing those issues. A literature review of current advancements and discoveries in linking the Heat Atlas and energy system models will be presented......In the past four decades following the global oil crisis in 1973, Denmark has implemented remarkable changes in its energy sector, mainly due to energy conservation measures on the demand side and energy efficiency improvements on the supply side. Nowadays the optimal expansion of district heating...

  18. Understanding the dynamics of the adoption of renewable energy technologies: A system dynamics approach

    Directory of Open Access Journals (Sweden)

    Michael Mutingi

    2013-04-01

    Full Text Available Renewable energy technologies (RET have faced a number of constraints that have affected their rate of adoption. This can be attributed to the presence of complex dynamic factors associated with the technology adoption process. This paper simulates the dynamic behaviour of the RET adoption process, from a systems dynamics point of view. Complex dynamic interactions between technology adopters, policy makers and policies are captured based on systems thinking concepts. Based on a set of input policy parameters and variables, the behaviour of RET adoption is investigated and analyzed. Sensitivity experiments and further “what-if” experiments are carried out to obtain in-depth understanding of RET adoption process. Useful managerial insights are drawn from the simulation results, relevant to decision makers concerned with renewable energy technology innovations and their adoption.

  19. Impact of forecast errors on expansion planning of power systems with a renewables target

    DEFF Research Database (Denmark)

    Pineda, Salvador; Morales González, Juan Miguel; Boomsma, Trine Krogh

    2015-01-01

    and transmission expansion plan that minimizes system-wide investment and operating costs, while ensuring a given share of renewable generation in the electricity supply. Unlike existing ones, this framework includes both a day-ahead and a balancing market so as to capture the impact of both......This paper analyzes the impact of production forecast errors on the expansion planning of a power system and investigates the influence of market design to facilitate the integration of renewable generation. For this purpose, we propose a programming modeling framework to determine the generation...... production forecasts and the associated prediction errors. Within this framework, we consider two paradigmatic market designs that essentially differ in whether the day-ahead generation schedule and the subsequent balancing re-dispatch are co-optimized or not. The main features and results of the model set...

  20. Storage and balancing synergies in a fully or highly renewable pan-European power system

    DEFF Research Database (Denmark)

    Rasmussen, Morten Grud; Bruun Andresen, Gorm; Greiner, Martin

    2012-01-01

    that combined with a low-efficiency hydrogen storage and a level of balancing equal to what is today provided by storage lakes, it is sufficient to meet the European electricity demand in a fully renewable power system where the average power generation from combined wind and solar exceeds the demand......Through a parametric time-series analysis of eight years of hourly data, we quantify the storage size and balancing energy needs for highly and fully renewable European power systems for different levels and mixes of wind and solar energy. By applying a dispatch strategy that minimizes the...... balancing energy needs for a given storage size, the interplay between storage and balancing is quantified, providing a hard upper limit on their synergy. An efficient but relatively small storage reduces balancing energy needs significantly due to its influence on intra-day mismatches. Furthermore, we show...

  1. Analysis of renewable energy sources and electric vehicle penetration into energy systems predominantly based on lignite

    Science.gov (United States)

    Dedinec, A.; Jovanovski, B.; Gajduk, A.; Markovska, N.; Kocarev, L.

    2016-05-01

    We consider an integration of renewable energy into transport and electricity sectors through vehicle to grid (V2G) technologies for an energy system that is predominantly based on lignite. The national energy system of Macedonia is modeled using EnergyPLAN which integrates energy for electricity, transport and heat, and includes hourly fluctuations in human needs and the environment. We show that electric-vehicles can provide the necessary storage enabling a fully renewable energy profile for Macedonia that can match the country's growing demand for energy. Furthermore, a large penetration of electric vehicles leads to a dramatic reduction of 47% of small particles and other air pollutants generated by car traffic in 2050.

  2. Renewable Electric Plant Information System user interface manual: Paradox 7 Runtime for Windows

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    The Renewable Electric Plant Information System (REPiS) is a comprehensive database with detailed information on grid-connected renewable electric plants in the US. The current version, REPiS3 beta, was developed in Paradox for Windows. The user interface (UI) was developed to facilitate easy access to information in the database, without the need to have, or know how to use, Paradox for Windows. The UI is designed to provide quick responses to commonly requested sorts of the database. A quick perusal of this manual will familiarize one with the functions of the UI and will make use of the system easier. There are six parts to this manual: (1) Quick Start: Instructions for Users Familiar with Database Applications; (2) Getting Started: The Installation Process; (3) Choosing the Appropriate Report; (4) Using the User Interface; (5) Troubleshooting; (6) Appendices A and B.

  3. Stochastic simulation of power systems with integrated renewable and utility-scale storage resources

    Science.gov (United States)

    Degeilh, Yannick

    The push for a more sustainable electric supply has led various countries to adopt policies advocating the integration of renewable yet variable energy resources, such as wind and solar, into the grid. The challenges of integrating such time-varying, intermittent resources has in turn sparked a growing interest in the implementation of utility-scale energy storage resources ( ESRs), with MWweek storage capability. Indeed, storage devices provide flexibility to facilitate the management of power system operations in the presence of uncertain, highly time-varying and intermittent renewable resources. The ability to exploit the potential synergies between renewable and ESRs hinges on developing appropriate models, methodologies, tools and policy initiatives. We report on the development of a comprehensive simulation methodology that provides the capability to quantify the impacts of integrated renewable and ESRs on the economics, reliability and emission variable effects of power systems operating in a market environment. We model the uncertainty in the demands, the available capacity of conventional generation resources and the time-varying, intermittent renewable resources, with their temporal and spatial correlations, as discrete-time random processes. We deploy models of the ESRs to emulate their scheduling and operations in the transmission-constrained hourly day-ahead markets. To this end, we formulate a scheduling optimization problem (SOP) whose solutions determine the operational schedule of the controllable ESRs in coordination with the demands and the conventional/renewable resources. As such, the SOP serves the dual purpose of emulating the clearing of the transmission-constrained day-ahead markets (DAMs ) and scheduling the energy storage resource operations. We also represent the need for system operators to impose stricter ramping requirements on the conventional generating units so as to maintain the system capability to perform "load following'', i

  4. Power Electronics – Key Technology for Renewable Energy Systems – Status and Future

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Yang, Yongheng; Ma, Ke

    2013-01-01

    , distribution and use of the energy should be as technological efficient as possible and incentives to save energy at the end-user should also be streng-thened. In order to realize the transition smoothly and effectively, energy conversion systems, currently based on power electronics technology, will again...... play an essential role. Using highly efficient power electronics in power generation, power transmission/ distribution and end-user application, together with advanced control solutions, can pave the way for renewable energies. In view of this, some of the most emerging renewable energies, e.g. wind...... energy and photovoltaic, which by means of power electronics are changing character as a major part in the electricity generation, are explored in this paper. Issues like technology development, implementation, power converter technologies, control of the systems, and synchronization are addressed...

  5. Modelling imperfect maintenance and the reliability of complex systems using superposed renewal processes

    International Nuclear Information System (INIS)

    In problems of maintenance optimization, it is convenient to assume that repairs are equivalent to replacements and that systems or objects are, therefore, brought back into an as good as new state after each repair. Standard results in renewal theory may then be applied for determining optimal maintenance policies. In practice, there are many situations in which this assumption cannot be made. The quintessential problem with imperfect maintenance is how to model it. In many cases it is very difficult to assess by how much a partial repair will improve the condition of a system or object and it is equally difficult to assess how such a repair influences the rate of deterioration. In this paper, a superposition of renewal process is used to model the effect of imperfect maintenance. It constitutes a different modelling approach than the more common use of a virtual age process.

  6. A holistic approach towards optimal planning of hybrid renewable energy systems: Combining hydroelectric and wind energy

    Science.gov (United States)

    Dimas, Panagiotis; Bouziotas, Dimitris; Efstratiadis, Andreas; Koutsoyiannis, Demetris

    2014-05-01

    Hydropower with pumped storage is a proven technology with very high efficiency that offers a unique large-scale energy buffer. Energy storage is employed by pumping water upstream to take advantage of the excess of produced energy (e.g. during night) and next retrieving this water to generate hydro-power during demand peaks. Excess energy occurs due to other renewables (wind, solar) whose power fluctuates in an uncontrollable manner. By integrating these with hydroelectric plants with pumped storage facilities we can form autonomous hybrid renewable energy systems. The optimal planning and management thereof requires a holistic approach, where uncertainty is properly represented. In this context, a novel framework is proposed, based on stochastic simulation and optimization. This is tested in an existing hydrosystem of Greece, considering its combined operation with a hypothetical wind power system, for which we seek the optimal design to ensure the most beneficial performance of the overall scheme.

  7. Analysis of renewable energy sources and electric vehicle penetration into energy systems predominantly based on lignite

    CERN Document Server

    Dedinec, Aleksandar; Gajduk, Andrej; Markovska, Natasa; Kocarev, Ljupco

    2016-01-01

    We consider an integration of renewable energy into transport and electricity sectors through vehicle to grid (V2G) technologies for an energy system that is predominantly based on lignite. The national energy system of Macedonia is modeled using EnergyPLAN which integrates energy for electricity, transport and heat, and includes hourly fluctuations in human needs and the environment. We show that electric-vehicles can provide the necessary storage enabling a fully renewable energy profile for Macedonia that can match the country's growing demand for energy. Furthermore, a large penetration of electric vehicles leads to a dramatic reduction of 47% of small particles and other air pollutants generated by car traffic in 2050.

  8. The Role of MEK Kinase 1 in Bcr-Abl-Induced Self-Renewal Activity of Embryonic Stem Cells

    OpenAIRE

    NAKAMURA, Yukinori; Yujiri, Toshiaki; Tanizawa, Yukio

    2006-01-01

    BCR-ABL oncogene, the moecular hallmark of chronic mylogenous leukemia, arises in a promitive hematopoietic stem cell that has the capacity for both differentiation and self-renewal. Its product, Bcr-Abl protein, has been shown to sctivate signal transducers and activators of transcription 3 (STAT3) and to promote self-renewal in embryonic stem (ES)cells, even in the absencs of leukemia in hibitory factor (LIF). MEK kinase 1 (MEKK1) is a 196-kDa mitogen-activated protein kinase (MAPK) kinase ...

  9. Comparison study between a Renewable Energy Supply System and a supergrid for achieving 100% from renewable energy sources in Islands

    DEFF Research Database (Denmark)

    Xydis, George

    2013-01-01

    Numerous efforts have been done for achieving the maximum penetration of renewable energy sources (RESs) in the autonomous grids of Greek islands, which never exceeded 10%, despite the exceptional wind and solar potential. Large fluctuations on demand during summer, winter, and 24-h period in...... even 100% and simultaneously reduce drastically the fuel costs. Furthermore, a supergrid is examined and compared with RESS as another efficient way for achieving higher penetration of RES....

  10. Optimal system management of a water pumping and desalination process supplied with intermittent renewable sources

    OpenAIRE

    Roboam, Xavier; Sareni, Bruno; Nguyen, Duc Trung; Belhadj, Jamel

    2012-01-01

    This paper aims at defining energy management strategy for a water pumping and desalination process which would be powered by a hybrid (solar PV & wind) renewable generation system. Several pumping subsystems for well pumping, water storage and desalination are coupled. The particularity of the proposed architecture with its management deals with the absence of electrochemical storage, only taking benefit of hydraulic storage in water tanks: in such an autonomous device, given a certain level...

  11. Strategies towards a 100% renewable energy system for Denmark in the Future Climate Project

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad

    2009-01-01

    Greenhouse gas mitigation strategies are generally considered costly with world leaders often engaging in debate concerning the costs of mitigation and the distribution of these costs between different countries. In this paper, the analyses and results of the design of a 100 per cent renewable...... business-as-usual energy system. Hence the current debate between leaders should reflect a combination of these two main challenges....

  12. Global Renewable Energy-Based Electricity Generation and Smart Grid System for Energy Security

    OpenAIRE

    M A Islam; M. Hasanuzzaman; Rahim, N. A.; Nahar, A.; Hosenuzzaman, M.

    2014-01-01

    Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for fu...

  13. Keeping an eye on reliability: the organizational requirements of future renewable energy systems

    OpenAIRE

    Scholten, D.J.

    2012-01-01

    The reliable operation of energy infrastructures is more than just a technical matter. It is also dependent upon the organizational structure that enables and constrains entities in their management of operations. Yet this lesson seems forgotten in our planning of future renewable energy systems. There, focus is on technical development, market deployment, and supporting government policies. Much less attention has been given to the broader organizational requirements necessary to ensure thei...

  14. Advanced Organic Vapor Cycles for Improving Thermal Conversion Efficiency in Renewable Energy Systems

    OpenAIRE

    Ho, Tony

    2012-01-01

    The Organic Flash Cycle (OFC) is proposed as a vapor power cycle that could potentially increase power generation and improve the utilization efficiency of renewable energy and waste heat recovery systems. A brief review of current advanced vapor power cycles including the Organic Rankine Cycle (ORC), the zeotropic Rankine cycle, the Kalina cycle, the transcritical cycle, and the trilateral flash cycle is presented. The premise and motivation for the OFC concept is that essentially by impro...

  15. Testing and preventive maintenance scheduling optimization for aging systems modeled by generalized renewal process

    OpenAIRE

    Vinícius Correa Damaso; Pauli Adriano de Almada Garcia

    2009-01-01

    The use of stochastic point processes to model the reliability of repairable systems has been a regular approach to establish survival measures in failure versus repair scenarios. However, the traditional processes do not consider the actual state in which an item returns to operational condition. The traditional renewal process considers an "as-good-as-new" philosophy, while a non-homogeneous Poisson process is based on the minimal repair concept. In this work, an approach based on the conce...

  16. Analytical investigation of low temperature lift energy conversion systems with renewable energy source

    International Nuclear Information System (INIS)

    The efficiency of the renewable energy powered energy conversion system is typically low due to its moderate heat source temperature. Therefore, improving its energy efficiency is essential. In this study, the performance of the energy conversion system with renewable energy source was theoretically investigated in order to explore its design aspect. For this purpose, a computer model of n-stage low temperature lift energy conversion (LTLEC) system was developed. The results showed that under given operating conditions such as temperatures and mass flow rates of heat source and heat sink fluids the unit power generation of the system increased with the number of stage, and it became saturated when the number of staging reached four. Investigation of several possible working fluids for the optimum stage LTLEC system revealed that ethanol could be an alternative to ammonia. The heat exchanger effectiveness is a critical factor on the system performance. The power generation was increased by 7.83% for the evaporator and 9.94% for the condenser with 10% increase of heat exchanger effectiveness. When these low temperature source fluids are applied to the LTLEC system, the heat exchanger performance would be very critical and it has to be designed accordingly. - Highlights: •Energy conversion system with renewable energy is analytically investigated. •A model of multi-stage low temperature lift energy conversion systems was developed. •The system performance increases as the stage number is increased. •The unit power generation is increased with increase of HX effectiveness. •Ethanol is found to be a good alternative to ammonia

  17. Single-Cell Analyses of ESCs Reveal Alternative Pluripotent Cell States and Molecular Mechanisms that Control Self-Renewal

    Directory of Open Access Journals (Sweden)

    Dmitri Papatsenko

    2015-08-01

    Full Text Available Analyses of gene expression in single mouse embryonic stem cells (mESCs cultured in serum and LIF revealed the presence of two distinct cell subpopulations with individual gene expression signatures. Comparisons with published data revealed that cells in the first subpopulation are phenotypically similar to cells isolated from the inner cell mass (ICM. In contrast, cells in the second subpopulation appear to be more mature. Pluripotency Gene Regulatory Network (PGRN reconstruction based on single-cell data and published data suggested antagonistic roles for Oct4 and Nanog in the maintenance of pluripotency states. Integrated analyses of published genomic binding (ChIP data strongly supported this observation. Certain target genes alternatively regulated by OCT4 and NANOG, such as Sall4 and Zscan10, feed back into the top hierarchical regulator Oct4. Analyses of such incoherent feedforward loops with feedback (iFFL-FB suggest a dynamic model for the maintenance of mESC pluripotency and self-renewal.

  18. Feasibility and impact analysis of a renewable energy source (RES)-based energy system in Korea

    International Nuclear Information System (INIS)

    In this study, we analyze the feasibility and impacts of a renewable energy source (RES)-based electricity supply system of future Korea. To achieve this goal, we first developed different scenarios for increasing the contribution of RES by lowering the rate of i) nuclear power, ii) thermal power, iii) both nuclear and thermal power, and iv) these scenarios with real-world constraints. Based on the generated scenarios, we then specified the established systems with practical strategies which encourage different renewable sources (wind, solar photovoltaic, biomass, and waste). Finally, we analyzed the impacts of the established RES-based systems according to various criteria: the total required cost, the dependence on imported energy, CO2 emissions, and land use. The results show that the RES-based system that utilizes wind energy as its main source by steadily decreasing the rate of thermal power for electricity generation is the most affordable for future Korean electricity system. We also identify the merits and drawbacks of the analyzed systems and provide relevant recommendations for the establishment of a sustainable energy system for Korea. These findings will support policy makers in integrating quantitative assessments into energy-related policy design and implementation. - Highlights: • We model and analyze RES-based electricity supply system in Korea. • Impact analysis includes: economic, energy security, environmental protection aspects. • We also evaluate different strategies to establish RES-based system. • We show that wind energy-based system is the most affordable for Korea

  19. Hybrid Systems of Distributed Generation with Renewable Sources: Modeling and Analysis of Their Operational Modes in Electric Power System

    Directory of Open Access Journals (Sweden)

    A. Gashimov

    2013-01-01

    Full Text Available The paper considers problems pertaining to modeling and simulation of operational hybrid system modes of the distributed generation comprising conventional sources – modular diesel generators, gas-turbine power units; and renewable sources – wind and solar power plants. Operational modes of the hybrid system have been investigated under conditions of electrical connection with electric power system and in case of its isolated operation. As a consequence

  20. Performance evaluation of renewable energy support policies, applied on Flanders' tradable certificates system

    International Nuclear Information System (INIS)

    The article is composed as a diptych. First, a general framework of criteria to evaluate the performance of renewable energy support systems is elaborated. It is built around the main criteria effectiveness, efficiency and equity. All three are multi-layered and specifying the contents of the various layers is case dependent. Second, the framework is applied on detailed data about the Flemish tradable certificates support system. Several salient conclusions confirm observations from research in other countries causing growing awareness. First, most crucial is a careful and detailed qualification of renewable energy sources and technologies. Without, even effectiveness is not reliably measurable. Second, nearby targets of renewable energy output must follow from a clearly designed transition trajectory towards a sustainable electricity sector. Such transition is intertwined with an industrial technological policy for bringing the necessary technologies to development and maturity. Third, if the above two prerequisites are overridden certificates systems abound of excess profits, predominantly reaped by incumbent power companies being not the best agents of real change to a sustainable energy future

  1. Switch: a planning tool for power systems with large shares of intermittent renewable energy.

    Science.gov (United States)

    Fripp, Matthias

    2012-06-01

    Wind and solar power are highly variable, so it is it unclear how large a role they can play in future power systems. This work introduces a new open-source electricity planning model--Switch--that identifies the least-cost strategy for using renewable and conventional generators and transmission in a large power system over a multidecade period. Switch includes an unprecedented amount of spatial and temporal detail, making it possible to address a new type of question about the optimal design and operation of power systems with large amounts of renewable power. A case study of California for 2012-2027 finds that there is no maximum possible penetration of wind and solar power--these resources could potentially be used to reduce emissions 90% or more below 1990 levels without reducing reliability or severely raising the cost of electricity. This work also finds that policies that encourage customers to shift electricity demand to times when renewable power is most abundant (e.g., well-timed charging of electric vehicles) could make it possible to achieve radical emission reductions at moderate costs. PMID:22506835

  2. Cell Maintenance Systems

    Science.gov (United States)

    Morrison, D. R.

    1985-01-01

    Living human cells require attachment to a suitable surface and special culture conditions in order to grow. These requirements are modified and amplified when cells are taken into a weightless environment. Special handling and maintenance systems are required for routine laboratory procedures conducted in the Orbiter and in the Spacelab. Methods were developed to maintain cells in special incubators designed for the Orbiter middeck, however, electrophoresis and other experiments require cells to be harvested off of the culture substrate before they can be processed or used. The cell transport assembly (CTA) was flown on STS-8, and results show that improvements are required to maintain adequate numbers of cells in this device longer than 48 hours. The life sciences middeck centrifuge probably can be used, but modifications will be required to transfer cells from the CTA and keep the cells sterile. Automated systems such as the Skylab SO-15 flight hardware and crew operated systems are being evaluated for use on the Space Shuttle, Spacelab, and Space Station research modules.

  3. A Review on Technologies and Methods of Mitigating Impacts of Large-Scale Intermittent Renewable Generations on Power System

    Directory of Open Access Journals (Sweden)

    Yujiao Liu

    2013-03-01

    Full Text Available With environmental pressure and the development of smart grid, penetration of large-scale renewable energy to power system seems to be imperative. However, it encounters some obstacles because of intermittencies of Renewable Generations (RGs. So mitigating impacts of intermittent RGs is a key issue for development of power system and this study presents a review on recent researches referring the problem from both electrical technologies and human factors. Technologies of storage, advance automation, electric vehicles, demand side management, risk constraint power system management, policies of renewable energies and the future research directions of them were discussed by the bibliographical survey.

  4. Optimal Operation of the Integrated Electrical and Heating Systems to Accommodate the Intermittent Renewable Sources

    DEFF Research Database (Denmark)

    Li, Jinghua; Fang, Jiakun; Zeng, Qing;

    2016-01-01

    conversion between the electrical system and heating system was optimally decided so that the demand within both systems could be met at the least operational cost. Besides, the best node to join with the electrical system and heating system was chosen by consideration of the energy transmission loss. The...... effectiveness of the proposed solution. The results showed that coordinated optimization of the energy distribution have significant benefits for reducing wind curtailment, operation cost, and energy losses. The proposed model and methodology could help system operators with decision support in the emerging......The integration of electrical and heating systems has great potential to enhance the flexibility of power systems to accommodate more renewable power such as the wind and solar. This study was to investigate an optimal way to integrate the energy of both systems in urban areas. The amount of energy...

  5. Intelligent energy management of optimally located renewable energy systems incorporating PHEV

    International Nuclear Information System (INIS)

    Highlights: • The algorithm optimally selects the number, locations and sizes of DGs. • Wind units, PV units, diesel units and PHEV parking lots are considered as DGs. • The algorithm determines the corresponding energy scheduling of resources. • The problem is formulated as an optimization problem solved using ABC. • The objective is to minimize the overall energy cost of the system. - Abstract: The recent interest in plug-in-hybrid electric vehicles (PHEV) results in the increase in the utilization of vehicles batteries for grid support. In addition, the integration of renewable energy systems (RES) into electricity grid is a promising technique for addressing the environmental concerns. This paper presents a multi-objective algorithm to optimally allocate a number of renewable energy systems including parking lots for PHEV in a distribution system. The proposed algorithm determines the number, locations and sizes of the RES and parking lots. In addition, a rule based expert system is used to find the corresponding energy scheduling of the system resources. The objective of the proposed algorithm is to minimize the overall energy cost of the system. The problem is formulated as an optimization problem which is solved using artificial bee colony (ABC) algorithm taking into consideration the power system and PHEV operational constraints. The proposed algorithm is applied to a 45-bus distribution network of Alexandria, Egypt. The test results indicate an improvement in the operational conditions of the system

  6. Energy system analysis of 100% renewable energy systems-The case of Denmark in years 2030 and 2050

    DEFF Research Database (Denmark)

    Lund, Henrik; Mathiesen, Brian Vad

    2009-01-01

    This paper presents the methodology and results of the overall energy system analysis of a 100% renewable energy system. The input for the systems is the result of a project of the Danish Association of Engineers, in which 1600 participants during more than 40 seminars discussed and designed a...... model for the future energy system of Denmark. The energy system analysis methodology includes hour by hour computer simulations leading to the design of flexible energy systems with the ability to balance the electricity supply and demand. The results are detailed system designs and energy balances for...

  7. EGFR/Src/Akt signaling modulates Sox2 expression and self-renewal of stem-like side-population cells in non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Singh Sandeep

    2012-09-01

    Full Text Available Abstract Background Cancer stem cells are thought to be responsible for the initiation and progression of cancers. In non-small cell lung cancers (NSCLCs, Hoechst 33342 dye effluxing side population (SP cells are shown to have stem cell like properties. The oncogenic capacity of cancer stem-like cells is in part due to their ability to self-renew; however the mechanistic correlation between oncogenic pathways and self-renewal of cancer stem-like cells has remained elusive. Here we characterized the SP cells at the molecular level and evaluated its ability to generate tumors at the orthotopic site in the lung microenvironment. Further, we investigated if the self-renewal of SP cells is dependent on EGFR mediated signaling. Results SP cells were detected and isolated from multiple NSCLC cell lines (H1650, H1975, A549, as well as primary human tumor explants grown in nude mice. SP cells demonstrated stem-like properties including ability to self-renew and grow as spheres; they were able to generate primary and metastatic tumors upon orthotopic implantation into the lung of SCID mice. In vitro study revealed elevated expression of stem cell associated markers like Oct4, Sox2 and Nanog as well as demonstrated intrinsic epithelial to mesenchymal transition features in SP cells. Further, we show that abrogation of EGFR, Src and Akt signaling through pharmacological or genetic inhibitors suppresses the self-renewal growth and expansion of SP-cells and resulted in specific downregulation of Sox2 protein expression. siRNA mediated depletion of Sox2 significantly blocked the SP phenotype as well as its self-renewal capacity; whereas other transcription factors like Oct4 and Nanog played a relatively lesser role in regulating self-renewal. Interestingly, Sox2 was elevated in metastatic foci of human NSCLC samples. Conclusions Our findings suggest that Sox2 is a novel target of EGFR-Src-Akt signaling in NSCLCs that modulates self-renewal and expansion of

  8. Renewable energy distributed power system with photovoltaic/ thermal and bio gas power generators

    International Nuclear Information System (INIS)

    The energy shortage and environmental pollution is becoming an important problem in these days. Hence it is very much important to use renewable power technologies to get rid of these problems. The important renewable energy sources are Bio-Energy, Wind Energy, Hydrogen Energy, Tide Energy, Terrestrial Heat Energy, Solar Energy, Thermal Energy and so on. Pakistan is rich in all these aspects particularly in Solar and Thermal Energies. In major areas of Pakistan like in South Punjab, Sind and Baluchistan the weather condition are very friendly for these types of Renewable Energies. In these areas Solar Energy can be utilized by solar panels in conjunction with thermal panels. The Photovoltaic cells are used to convert Solar Energy directly to Electrical Energy and thermal panels can be uses to convert solar energy into heat energy and this heat energy will be used to drive some turbine to get Electrical Energy. The Solar Energy can be absorbed more efficiently by any given area of Solar Panel if these two technologies can be combined in such a way that they can work together. The first part of this paper shows that how these technologies can be combined. Furthermore it is known to all that photovoltaic/thermal panels depend entirely on weather conditions. So in order to maintain constant power a biogas generator is used in conjunction with these. (author)

  9. A Process for the Implementation of New Renewable Energy Systems in a Building by Considering Environmental and Economic Effect

    Directory of Open Access Journals (Sweden)

    Chan-Joong Kim

    2015-09-01

    Full Text Available The excessive use of fossil fuels has led to global warming and air pollution. To solve these problems, interest in new renewable energy system (NRE system has increased in recent years. In particular, photovoltaic, solar thermal heating, fuel cell and ground source heating system are actively implemented for achieving the zero energy building. Since the initial investment cost of the NRE system is quite expensive, it is necessary to conduct a feasibility study from the life cycle perspective. Therefore, this study aimed to develop the process for the implementation of NRE system in a building for the optimal design. This study was conducted with four steps: (i establishing the basic information for the system installation; (ii selecting key factors affecting system performances; (iii making possible alternatives of the system installation; and (iv selecting optimal system by considering environmental and economic effect. The proposed process could enable the final decision-maker to easily and accurately determine the optimal design of the NRE systems from the economic and environmental efficiency in the early design phase. The process could also be applied to any other NRE system and could be extended to any other country in the global environment.

  10. Cogeneration and beyond: The need and opportunity for high efficiency, renewable community energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Gleason, T.C.J.

    1992-06-01

    The justification, strategies, and technology options for implementing advanced district heating and cooling systems in the United States are presented. The need for such systems is discussed in terms of global warming, ozone depletion, and the need for a sustainable energy policy. Strategies for implementation are presented in the context of the Public Utilities Regulatory Policies Act and proposed new institutional arrangements. Technology opportunities are highlighted in the areas of advanced block-scale cogeneration, CFC-free chiller technologies, and renewable sources of heating and cooling that are particularly applicable to district systems.

  11. Cogeneration and beyond: The need and opportunity for high efficiency, renewable community energy systems

    International Nuclear Information System (INIS)

    The justification, strategies, and technology options for implementing advanced district heating and cooling systems in the United States are presented. The need for such systems is discussed in terms of global warming, ozone depletion, and the need for a sustainable energy policy. Strategies for implementation are presented in the context of the Public Utilities Regulatory Policies Act and proposed new institutional arrangements. Technology opportunities are highlighted in the areas of advanced block-scale cogeneration, CFC-free chiller technologies, and renewable sources of heating and cooling that are particularly applicable to district systems

  12. Adult Stem Cells as a Renewable Source of Insulin-Producing Cells

    OpenAIRE

    Jun, Hee-Sook; Park, Eun-Young

    2009-01-01

    Diabetes mellitus is a metabolic disorder resulting from an inadequate mass of insulin-producing pancreatic beta cells. The replacement or restoration of damaged beta cells would be considered the optimal therapeutic options. Islet transplantation seems to be a promising approach for replacement therapy; however, the main obstacle is the shortage of organ donors. As mature beta cells have been shown to be difficult to expand in vitro, regeneration of beta cells from embryonic or adult stem ce...

  13. Inhibition of lung cancer stem cells self-renewal and tumorigenicity by lentivirus-delivered Bmi1 shRNA

    Institute of Scientific and Technical Information of China (English)

    Jing Zhou; Yu Xu; Ping Hao; Yide Hu

    2011-01-01

    Objective: The aim of the study was to observe the effect of Bmi1 reduction on the self-renewal and tumorigenic-ity ability of lung cancer stem cells (LCSCs) in human lung adenocarcinoma. Methods: Human lung adenocarcinoma cells A549 were consecutively passaged in NOD/SCID mice treated with Paclitaxel weekly. The proportions of LCSCs in A549 cells and the cells from the third passage (A549-3rd) were compared. The expression of Bmi1 in LCSCs was silenced by intratumoral injection with lentivirus-delivered Bmi1 small hairpin RNA (shRNA). RT-PCR and Western blot were used to test the mRNA and protein expressions of Bmi1 in LCSCs. The protein level of p16INK4A was analyzed by Western blotting. The self-renewal and tumorigenicity ability of LCSCs were evaluated by counting the sphere formation rate in serum-free medium and the tumor formation rate in NOD/SCID mice. Results: In vivo passaging of A549 cells under chemotherapy pressure enriched for LCSCs. The expression of Bmi1 in LCSCs increased. Down-regulation of Bmi1 by RNA interference resulted in reduced self-renewal and tumorigenicity ability of LCSCs and paralleled the increased expression of p16INK4A, a Bmi1 target. Conclu-sion: Bmi1 regulates self-renewal and tumorigenicity of LCSCs by silencing some target genes, including p16INK4A.

  14. RESRO: A spatio-temporal model to optimise regional energy systems emphasising renewable energies

    Directory of Open Access Journals (Sweden)

    Gadocha S.

    2012-10-01

    Full Text Available RESRO (Reference Energy System Regional Optimization optimises the simultaneous fulfilment of the heat and power demand in regional energy systems. It is a mixed-integer program realised in the modelling language GAMS. The model handles information on geographically disaggregated data describing heat demand and renewable energy potentials (e.g. biomass, solar energy, ambient heat. Power demand is handled spatially aggregated in an hourly time resolution within 8 type days. The major idea is to use a high-spatial, low-temporal heat resolution and a low-spatial, hightemporal power resolution with both demand levels linked with each other. Due to high transport losses the possibilities for heat transport over long distances are unsatisfying. Thus, the spatial, raster-based approach is used to identify and utilise renewable energy resources for heat generation close to the customers as well as to optimize district heating grids and related energy flows fed by heating plants or combined heat and power (CHP plants fuelled by renewables. By combining the heat and electricity sector within the model, it is possible to evaluate relationships between these energy fields such as the use of CHP or heat pump technologies and also to examine relationships between technologies such as solar thermal and photovoltaic facilities, which are in competition for available, suitable roof or ground areas.

  15. RESRO: A spatio-temporal model to optimise regional energy systems emphasising renewable energies

    Science.gov (United States)

    Hausl, S.; Biberacher, M.; Gadocha, S.

    2012-10-01

    RESRO (Reference Energy System Regional Optimization) optimises the simultaneous fulfilment of the heat and power demand in regional energy systems. It is a mixed-integer program realised in the modelling language GAMS. The model handles information on geographically disaggregated data describing heat demand and renewable energy potentials (e.g. biomass, solar energy, ambient heat). Power demand is handled spatially aggregated in an hourly time resolution within 8 type days. The major idea is to use a high-spatial, low-temporal heat resolution and a low-spatial, hightemporal power resolution with both demand levels linked with each other. Due to high transport losses the possibilities for heat transport over long distances are unsatisfying. Thus, the spatial, raster-based approach is used to identify and utilise renewable energy resources for heat generation close to the customers as well as to optimize district heating grids and related energy flows fed by heating plants or combined heat and power (CHP) plants fuelled by renewables. By combining the heat and electricity sector within the model, it is possible to evaluate relationships between these energy fields such as the use of CHP or heat pump technologies and also to examine relationships between technologies such as solar thermal and photovoltaic facilities, which are in competition for available, suitable roof or ground areas.

  16. Endothelial cell-initiated signaling promotes the survival and self-renewal of cancer stem cells

    OpenAIRE

    Krishnamurthy, Sudha; Dong, Zhihong; Vodopyanov, Dmitry; Imai, Atsushi; Helman, Joseph I.; Prince, Mark E.; Wicha, Max S.; Jacques E Nör

    2010-01-01

    Recent studies have demonstrated that cancer stem cells play an important role in the pathobiology of head and neck squamous cell carcinomas (HNSCC). However, little is known about functional interactions between head and neck cancer stem-like cells (CSC) and surrounding stromal cells. Here, we used Aldehyde Dehydrogenase activity and CD44 expression to sort putative stem cells from primary human HNSCC. Implantation of 1,000 CSC (ALDH+CD44+Lin−) led to tumors in 13 (out of 15) mice, while 10,...

  17. Optimized Renewable and Sustainable Electricity Generation Systems for Ulleungdo Island in South Korea

    Directory of Open Access Journals (Sweden)

    Kyeongsik Yoo

    2014-11-01

    Full Text Available The South Korean government has long been attempting to reduce the nation’s heavy reliance on fossil fuels and increase environmental safety by developing and installing renewable power generation infrastructures and implementing policies for promoting the green growth of Korea’s energy industry. This study focuses on the use of independent renewable power generation systems in the more than 3000 officially affirmed islands off Korea’s coast and proposes a simulated solution to the electricity load demand on Ulleungdo Island that incorporates several energy sources (including solar, batteries, and wind as well as one hydro-electric and two diesel generators. Recommendations based on the simulation results and the limitations of the study are discussed.

  18. Power Electronics – The Key Technology for Renewable Energy System Integration

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Yang, Yongheng; Ma, Ke;

    2015-01-01

    The energy paradigms in many countries (e.g. Germany and Denmark) have experienced a significant change from fossil-based resources to clean renewables (e.g. wind turbines and photovoltaics) in the past few decades. The scenario of highly penetrated renewables is going to be further enhanced...... – Denmark expects to be 100 % fossil-free by 2050. Consequently, it is required that the production, distribution and use of the energy should be as technologically efficient as possible and incentives to save energy at the end-user should also be strengthened. In order to realize the transition smoothly...... and effectively, energy conversion systems, currently based on power electronics technology, will again play an essential role in this energy paradigm shift. Using highly efficient power electronics in power generation, power transmission/distribution and end-user application, together with advanced...

  19. Design for reliability in power electronics in renewable energy systems – status and future

    DEFF Research Database (Denmark)

    Wang, Huai; Blaabjerg, Frede; Ma, Ke;

    2013-01-01

    maintenance costs, and herefore, low Levelized-Cost-of-Energy (LCOE) of renewable energy systems. This paper presents the prior-art Design for Reliability (DFR) process for power converters and addresses the paradigm shift to Physics-of-Failure (PoF) approach and mission profile based analysis. Moreover, the......Advances in power electronics enable efficient and flexible interconnection of renewable sources, loads and electric grids. While targets concerning efficiency of power converters are within reach, recent research endeavors to predict and improve their reliability to ensure high availability, low...... lifetime prediction of reliability-critical components IGBT modules is discussed in a 2.3 MW wind power converter. Finally, the challenges and opportunities to achieve more reliable power electronic converters are discussed....

  20. Roles of Retinoids and Retinoic Acid Receptors in the Regulation of Hematopoietic Stem Cell Self-Renewal and Differentiation

    Directory of Open Access Journals (Sweden)

    Louise E. Purton

    2007-01-01

    Full Text Available Multipotent hematopoietic stem cells (HSCs sustain blood cell production throughout an individual's lifespan through complex processes ultimately leading to fates of self-renewal, differentiation or cell death decisions. A fine balance between these decisions in vivo allows for the size of the HSC pool to be maintained. While many key factors involved in regulating HSC/progenitor cell differentiation and cell death are known, the critical regulators of HSC self-renewal are largely unknown. In recent years, however, a number of studies describing methods of increasing or decreasing the numbers of HSCs in a given population have emerged. Of major interest here are the emerging roles of retinoids in the regulation of HSCs.

  1. Creating Public Awareness of Renewable Energy by Combining a Photovoltaic System and Nature

    DEFF Research Database (Denmark)

    Knott, Arnold; Lund, Dorthe Hedensted; Andersen, Thomas

    2011-01-01

    mechanical requirements and the developed solution is shown, before providing intensive insight into the electrical configuration, consisting of a battery, photovoltaic cells and a DC-AC converter. Furthermore a low complexity charge controller is presented. The resulting solar tree is capable of attracting...... situation is quite clear to the experts in the field, but further awareness in the public must be created. Therefore this paper addresses a method of creating this awareness: installations that stimulate conversations of renewable energy. A solar tree was developed and built to serve young people with an AC...

  2. A comparison between renewable transport fuels that can supplement or replace biofuels in a 100% renewable energy system

    DEFF Research Database (Denmark)

    Connolly, David; Mathiesen, Brian Vad; Ridjan, Iva

    2014-01-01

    Identifying renewable energy alternatives in transport is particularly complicated, since the end-user can vary from a single-person car to a cargo ship. The aim of this paper is to aid this process by comparing 7 different methods for producing transport fuels in terms of the resources required...... form of energy dense fuel is also necessary. The results in this paper suggest that this fuel will be produced by hydrogenating either biomass or carbon dioxide, depending on the residual biomass available. Biomass gasification, steam electrolysis, and carbon capture are key technologies in the future...

  3. CXCR2 and CXCL4 regulate survival and self-renewal of hematopoietic stem/progenitor cells.

    Science.gov (United States)

    Sinclair, Amy; Park, Laura; Shah, Mansi; Drotar, Mark; Calaminus, Simon; Hopcroft, Lisa E M; Kinstrie, Ross; Guitart, Amelie V; Dunn, Karen; Abraham, Sheela A; Sansom, Owen; Michie, Alison M; Machesky, Laura; Kranc, Kamil R; Graham, Gerard J; Pellicano, Francesca; Holyoake, Tessa L

    2016-07-21

    The regulation of hematopoietic stem cell (HSC) survival and self-renewal within the bone marrow (BM) niche is not well understood. We therefore investigated global transcriptomic profiling of normal human HSC/hematopoietic progenitor cells [HPCs], revealing that several chemokine ligands (CXCL1-4, CXCL6, CXCL10, CXCL11, and CXCL13) were upregulated in human quiescent CD34(+)Hoescht(-)Pyronin Y(-) and primitive CD34(+)38(-), as compared with proliferating CD34(+)Hoechst(+)Pyronin Y(+) and CD34(+)38(+) stem/progenitor cells. This suggested that chemokines might play an important role in the homeostasis of HSCs. In human CD34(+) hematopoietic cells, knockdown of CXCL4 or pharmacologic inhibition of the chemokine receptor CXCR2, significantly decreased cell viability and colony forming cell (CFC) potential. Studies on Cxcr2(-/-) mice demonstrated enhanced BM and spleen cellularity, with significantly increased numbers of HSCs, hematopoietic progenitor cell-1 (HPC-1), HPC-2, and Lin(-)Sca-1(+)c-Kit(+) subpopulations. Cxcr2(-/-) stem/progenitor cells showed reduced self-renewal capacity as measured in serial transplantation assays. Parallel studies on Cxcl4 demonstrated reduced numbers of CFC in primary and secondary assays following knockdown in murine c-Kit(+) cells, and Cxcl4(-/-) mice showed a decrease in HSC and reduced self-renewal capacity after secondary transplantation. These data demonstrate that the CXCR2 network and CXCL4 play a role in the maintenance of normal HSC/HPC cell fates, including survival and self-renewal. PMID:27222476

  4. Modelling and control of hybrid renewable energy system connected to AC grid

    Directory of Open Access Journals (Sweden)

    Sami Younsi

    2011-12-01

    Full Text Available This paper discusses the development of new control and supervision method for the optimum operation of hybrid renewable energy system (HRES connected to AC grid. The hybrid system consists of wind generator (WG, diesel generator (DG, and flywheel energy storage system (FESS. These subsystems are based on permanent magnet synchronous machines (PMSM which are controlled by sliding mode control. A supervisor control is designed to determine the energy transfer type of flywheel energy storage system (charging / discharging / no transfer energy, to take decision on diesel generators ON/OFF status, and to determine the reference powers for these two subsystems. The supervisor inputs are the power requested by AC grid, the power generated by wind generator, and the energy stored in flywheel. The objectives of the control and supervision for hybrid renewable energy system are to satisfy the power requested by AC grid, to manage the energy transfer between hybrid system and AC grid, to optimize the use of wind energy, and to reduce fuel of diesel generator. The system is simulated with Matlab – Simulink software and it gave good results.

  5. ady State Analysis of Grid Connected Hybrid Renewable Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Dr. D. Padma Subramanian

    2014-08-01

    Full Text Available This paper presents an analysis on steady state behavior of grid connected hybrid renewable energy conversion systems (RECS. Modeling of Doubly Fed Induction Generator (DFIG for Wind Energy Conversion system (WECS and marine current energy system ,and modeling of PV module is presented. A procedure for incorporating WECS, marine current energy conversion system and solar energy conversion system into a power flow program is discussed. A gird interfaced power flow program is developed in MATLAB and effectiveness of developed program is tested on a standard IEEE-9 bus system. The impact of varying wind speed, marine velocity and solar irradiation values on the steady state behavior of the grid connected hybrid power system is studied and the results are presented.

  6. A status report on the design and implementation of state renewable portfolio standards and system benefits charge policies

    Energy Technology Data Exchange (ETDEWEB)

    Porter, K.; Wiser, R.

    2000-05-01

    At last year's Windpower conference, we reported on state policies to foster renewable energy as part of efforts to restructure state electric power markets. The primary policies states are pursuing for renewables are system benefits charges (SBC) and renewable portfolio standards (RPS). Renewable portfolio standard policies began taking effect this year, while other states are continuing to work on the design of their RPS implementation strategies. In addition, states have begun distributing proceeds from their SBC funds. As a result, some renewable energy projects are beginning to materialize. This paper provides an update on state efforts with these two policies and examines some of the implementation issues and difficulties that states have faced thus far.

  7. NF-YB Regulates Spermatogonial Stem Cell Self-Renewal and Proliferation in the Planarian Schmidtea mediterranea

    Science.gov (United States)

    Iyer, Harini; Collins, James J.; Newmark, Phillip A.

    2016-01-01

    Gametes are the source and carrier of genetic information, essential for the propagation of all sexually reproducing organisms. Male gametes are derived from a progenitor stem cell population called spermatogonial stem cells (SSCs). SSCs give rise to male gametes through the coordination of two essential processes: self-renewal to produce more SSCs, and differentiation to produce mature sperm. Disruption of this equilibrium can lead to excessive proliferation of SSCs, causing tumorigenesis, or can result in aberrant differentiation, leading to infertility. Little is known about how SSCs achieve the fine balance between self-renewal and differentiation, which is necessary for their remarkable output and developmental potential. To understand the mechanisms of SSC maintenance, we examine the planarian homolog of Nuclear Factor Y-B (NF-YB), which is required for the maintenance of early planarian male germ cells. Here, we demonstrate that NF-YB plays a role in the self-renewal and proliferation of planarian SSCs, but not in their specification or differentiation. Furthermore, we characterize members of the NF-Y complex in Schistosoma mansoni, a parasitic flatworm related to the free-living planarian. We find that the function of NF-YB in regulating male germ cell proliferation is conserved in schistosomes. This finding is especially significant because fecundity is the cause of pathogenesis of S. mansoni. Our findings can help elucidate the complex relationship between self-renewal and differentiation of SSCs, and may also have implications for understanding and controlling schistosomiasis. PMID:27304889

  8. Acute respiratory bronchiolitis: an ultrastructural and autoradiographic study of epithelial cell injury and renewal in Rhesus monkeys exposed to ozone

    International Nuclear Information System (INIS)

    The pathogenesis of acute respiratory bronchiolitis was examined in Rhesus monkeys exposed to 0.8 ppM ozone for 4 to 50 hours. Epithelial injury and renewal were qualitatively and quantitatively characterized by correlated techniques of scanning and transmission electron microscopy as well as by light-microscopic autoradiography following labeling with tritiated thymidine. Extensive degeneration and necrosis of Type 1 epithelial cells occurred on the respiratory bronchiolar wall during the initial 4 to 12 hours of exposure. Increased numbers of labeled epithelial cells were present in this region after 18 hours of exposure, and the highest labeling index (18%) was measured after 50 hours of exposure. Most (67 to 80%) of the labeled cells and all the mitotic epithelial cells (22) observed ultrastructurally were cuboidal bronchiolar epithelial cells. Of the labeled epithelial cells, 20 to 33% were Type 2 epithelial cells. After 50 hours of exposure the respiratory bronchiolar epithelium was hyperplastic. The predominant inflammatory cell in respiratory bronchiolar exudate was the alveolar macrophage. Monkeys that were exposed for 50 hours and allowed to recover in unozonized air for 7 days had incomplete resolution of respiratory bronchiolar epithelial hyperplasia. The results indicate that Type 1 epithelial cells lining respiratory bronchioles are the cell types most sensitive to injury and that both cuboidal bronchiolar epithelial cells and Type 2 epithelial cells function as stem cells in epithelial renewal

  9. A cost optimization model for 100% renewable residential energy supply systems

    DEFF Research Database (Denmark)

    Milan, Christian; Bojesen, Carsten; Nielsen, Mads Pagh

    2012-01-01

    interdependencies between the different supply technologies as well as the construction energy of the installations, consumption profiles and on-site energy resource availability. This paper aims at developing such a model for the optimal sizing of renewable energy supply systems (RES) for residential Net ZEB......The concept of net zero energy buildings (Net ZEB) has received increased attention throughout the last years. A well adapted and optimized design of the energy supply system is crucial for the performance of these buildings. To achieve this, a holistic approach is needed which accounts for the...

  10. The Realization of a Discrete-Time Deterministic Regulator for Energy Renewable Multivariable Systems

    Directory of Open Access Journals (Sweden)

    OBINABO, EDWIN CHUKWUDI

    2010-12-01

    Full Text Available This study proposes an optimal control law for a linear constant energy renewal multivariable system supplying power to protection and signaling circuits for switchgears and substation operations. The energy storage mechanism creates a control source that dictates the frequency of the pow er supply voltage. The entire analysis was based essentially on the use of a vector of inputs and outputs, and a matrix of operations characterizing the storage mechanism, assuming the system is both controllable and observable under arbitrary state feedback. The property of the output regulator which was desirable from the view point of feedback control design was clarified.

  11. Proceedings of the National Renewable Energy Laboratory Wind Energy Systems Engineering Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Dykes, K.

    2014-12-01

    The second National Renewable Energy Laboratory (NREL) Wind Energy Systems Engineering Workshop was held in Broomfield, Colorado, from January 29 to February 1, 2013. The event included a day-and-a-half workshop exploring a wide variety of topics related to system modeling and design of wind turbines and plants. Following the workshop, 2 days of tutorials were held at NREL, showcasing software developed at Sandia National Laboratories, the National Aeronautics and Space Administration's Glenn Laboratories, and NREL. This document provides a brief summary of the various workshop activities and includes a review of the content and evaluation results from attendees.

  12. A Power Supply System with ZVS and Current-Doubler Features for Hybrid Renewable Energy Conversion

    OpenAIRE

    Jye-Chau Su; Cheng-Tao Tsai; Chih-Lung Shen

    2013-01-01

    In this paper, a power supply system for hybrid renewable energy conversion is proposed, which can process PV (photovoltaic) power and wind-turbine energy simultaneously for step-down voltage and high current applications. It is a dual-input converter and mainly contains a PV energy source, a wind turbine energy source, a zero-voltage-switching (ZVS) forward converter, and a current-doubler rectifier. The proposed power supply system has the following advantages: (1) PV-arrays and wind-energy...

  13. Fuel cell systems

    International Nuclear Information System (INIS)

    Fuel cell systems are an entirely different approach to the production of electricity than traditional technologies. They are similar to the batteries in that both produce direct current through electrochemical process. There are six types of fuel cells each with a different type of electrolyte, but they all share certain important characteristics: high electrical efficiency, low environmental impact and fuel flexibility. Fuel cells serve a variety of applications: stationary power plants, transport vehicles and portable power. That is why world wide efforts are addressed to improvement of this technology. (Original)

  14. Responses of Cell Renewal Systems to Long-term Low-Level Radiation Exposure: A Feasibility Study Applying Advanced Molecular Biology Techniques on Available Histological and Cytological Material of Exposed Animals and Men

    International Nuclear Information System (INIS)

    First results of this feasibility study showed that evaluation of the stored material of the chronically irradiated dogs with modern molecular biological techniques proved to be successful and extremely promising. Therefore an in deep analysis of at least part of the huge amount of remaining material is of outmost interest. The methods applied in this feasibility study were pathological evaluation with different staining methods, protein analysis by means of immunohistochemistry, strand break analysis with the TdT-assay, DNA- and RNA-analysis as well as genomic examination by gene array. Overall more than 50% of the investigated material could be used. In particular the results of an increased stimulation of the immune system within the dogs of the 3mSv group as both compared to the control and higher dose groups gives implications for the in depth study of the cellular events occurring in context with low dose radiation. Based on the findings of this study a further evaluation and statistically analysis of more material can help to identify promising biomarkers for low dose radiation. A systematic evaluation of a correlation of dose rates and strand breaks within the dog tissue might moreover help to explain mechanisms of tolerance to IR. One central problem is that most sequences for dog specific primers are not known yet. The discovery of the dog genome is still under progress. In this study the isolation of RNA within the dog tissue was successful. But up to now there are no gene arrays or gene chips commercially available, tested and adapted for canine tissue. The uncritical use of untested genomic test systems for canine tissue seems to be ineffective at the moment, time consuming and ineffective. Next steps in the investigation of genomic changes after IR within the stored dog tissue should be limited to quantitative RT-PCR of tested primer sequences for the dog. A collaboration with institutions working in the field of the discovery of the dog genome could

  15. Renewable energy powered membrane technology. 1. Development and characterization of a photovoltaic hybrid membrane system.

    Science.gov (United States)

    Schäfer, A I; Broeckmann, A; Richards, B S

    2007-02-01

    In isolated communities where potable water sources as well as energy grids are limited or nonexistent, treating brackish groundwater aquifers with small-scale desalination systems can be a viable alternative to existing water infrastructures. Given the unavailability of power in many such situations, renewable energy is an obvious solution to power such systems. However, renewable energy is an intermittent power supply and with regards to the performance of intermittently operated desalination systems, only very limited experience exists, both with regards to efficiency as well as water quality. In this paper, this lack of knowledge is addressed by evaluating a system operated with varying parameters (pressure and flow) with constant power as a step toward defining a safe operating window, and they provide a basis for interpreting future data obtained with a renewable energy source. Field trials were performed on a brackish (5300 mg/L TDS; 8290 microS/cm) bore in Central Australia with a photovoltaic-powered membrane filtration (PV-membrane) system. Four nanofiltration and reverse osmosis membranes (BW30, ESPA4, NF90, TFC-S) and a number of operation parameter combinations (transmembrane pressure, feed flow, TFC-S) and operating parameters transmembrane pressure and feed flow were investigated to find the best operating conditions for maximum drinking water production and minimum specific energy consumption (SEC). The ESPA4 membrane performed best for this brackish source, producing 250 L/h of excellent drinking water (257 mg/L TDS; 400 microS/ cm) at an SEC of 1.2 kWh/m3. The issue of brine disposal or reuse is also discussed and the article compares the salinity of the produced brine with livestock water. Since the feedwater is disinfected physically using ultrafiltration (UF), the brine is free from bacteria and most viruses and hence can be seen more as a reusable product stream than a waste stream with a disposal problem. PMID:17328215

  16. Stochastic Methods Applied to Power System Operations with Renewable Energy: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Z. [Argonne National Lab. (ANL), Argonne, IL (United States); Liu, C. [Argonne National Lab. (ANL), Argonne, IL (United States); Electric Reliability Council of Texas (ERCOT), Austin, TX (United States); Botterud, A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-08-01

    Renewable energy resources have been rapidly integrated into power systems in many parts of the world, contributing to a cleaner and more sustainable supply of electricity. Wind and solar resources also introduce new challenges for system operations and planning in terms of economics and reliability because of their variability and uncertainty. Operational strategies based on stochastic optimization have been developed recently to address these challenges. In general terms, these stochastic strategies either embed uncertainties into the scheduling formulations (e.g., the unit commitment [UC] problem) in probabilistic forms or develop more appropriate operating reserve strategies to take advantage of advanced forecasting techniques. Other approaches to address uncertainty are also proposed, where operational feasibility is ensured within an uncertainty set of forecasting intervals. In this report, a comprehensive review is conducted to present the state of the art through Spring 2015 in the area of stochastic methods applied to power system operations with high penetration of renewable energy. Chapters 1 and 2 give a brief introduction and overview of power system and electricity market operations, as well as the impact of renewable energy and how this impact is typically considered in modeling tools. Chapter 3 reviews relevant literature on operating reserves and specifically probabilistic methods to estimate the need for system reserve requirements. Chapter 4 looks at stochastic programming formulations of the UC and economic dispatch (ED) problems, highlighting benefits reported in the literature as well as recent industry developments. Chapter 5 briefly introduces alternative formulations of UC under uncertainty, such as robust, chance-constrained, and interval programming. Finally, in Chapter 6, we conclude with the main observations from our review and important directions for future work.

  17. Integrated renewable energy systems for off grid rural electrification of remote area

    International Nuclear Information System (INIS)

    The off grid electrification by utilizing Integrated Renewable Energy System (IRES) is proposed to satisfy the electrical and cooking needs of the seven-uneletrified villages in the Almora district of Uttarakhand state, India. Four different scenarios are considered during modeling and optimization of IRES to ensure reliability parameters such as energy index ratio (EIR) and expected energy not supplied (EENS). The optimum system reliability, total system cost and cost of energy (COE) have also been worked out by introducing the customer interruption cost (CIC). The four different renewable energy scenarios have been compared for the considered study area using the LINGO software version 10. The fourth renewable energy scenario accounting 44.99% micro hydropower (MHP), 30.07% biomass, 5.19% biogas and 4.16% solar energy along with the additional resources of wind (1.27%) and energy plantation (12.33%) has been found to be the best among the different options considered. Furthermore, the optimal reliability for the fourth IRES system has been found to be 0.95 EIR at the optimized cost of Rs 19.44 lacs with estimated COE of Rs 3.36 per kWh. The COE obtained using LINGO software and HOMER software has also been compared and briefly discussed for all the four scenarios. In order to verify feasibility and cost of system for different biomass fuel prices, a sensitivity analysis has also been carried out and it has been found that the fourth scenario is more sustainable than the other considered options. (author)

  18. Pathways to Decarbonization. Natural Gas and Renewable Energy. Lessons Learned from Energy System Stakeholders

    Energy Technology Data Exchange (ETDEWEB)

    Pless, Jacquelyn [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Arent, Douglas J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Logan, Jeffrey [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cochran, Jaquelin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zinaman, Owen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stark, Camila [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-04-30

    Ensuring the resilience, reliability, flexibility, and affordability of the U.S. electric grid is increasingly important as the country addresses climate change and an aging infrastructure. State and federal policy and actions by industry, non-profits, and others create a dynamic framework for achieving these goals. Three principle low-carbon generation technologies have formed the basis for multiple scenarios leading toward a low-carbon, resilient, and affordable power system. While there is no “silver bullet,” one avenue identified by key stakeholders is the opportunity to invest in natural gas (NG) and renewable resources, both of which offer abundant domestic resource bases and contribute to energy independence, carbon mitigation, and economic growth. NG and renewable electricity (RE) have traditionally competed for market share in the power sector, but there is a growing experience base and awareness for their synergistic use (Cochran et al. 2014). Building upon these observations and previous work, the Joint Institute for Strategic Energy Analysis (JISEA), in collaboration with the Center for the New Energy Economy and the Gas Technology Institute, convened a series of workshops in 2014 to explore NG and RE synergies in the U.S. power sector. This report captures key insights from the workshop series, Synergies of Natural Gas and Renewable Energy: 360 Degrees of Opportunity, as well as supporting economic valuation analyses conducted by JISEA researchers that quantify the value proposition of investing in NG and RE together as complements.

  19. Solar, wind and waves: Natural limits to renewable sources of energy within the Earth system

    Energy Technology Data Exchange (ETDEWEB)

    Kleidon, Axel [Max-Planck-Institute for Biogeochemistry, Jena (Germany)

    2013-07-01

    Renewable sources of energy, such as solar, wind, wave, or hydropower, utilize energy that is continuously generated by natural processes within the Earth system from the planetary forcing. Here we estimate the limits of these natural energy conversions and the extent to which these can be used as renewable energy sources using the laws of thermodynamics. At most, wind power in the order of 1 000 TW (1 TW = 1E12 W) can be derived from the total flux of incoming solar radiation of 175 000 TW, which is consistent with estimates based on observations. Other generation rates that are derived from the kinetic energy of wind are in the order of 10-100 TW. In comparison, the human primary energy demand of about 17 TW constitutes a considerable fraction of these rates. We provide some further analysis on the limits of wind power using a combination of conceptual models, observational data, and numerical simulation models. We find that many current estimates of wind power substantially overestimate the potential of wind power because the effect of kinetic energy extraction on the air flow is neglected. We conclude that the only form of renewable energy that is available in substantial amounts and that is associated with minor climatic impacts is solar power.

  20. Solar, wind and waves: Natural limits to renewable sources of energy within the Earth system

    International Nuclear Information System (INIS)

    Renewable sources of energy, such as solar, wind, wave, or hydropower, utilize energy that is continuously generated by natural processes within the Earth system from the planetary forcing. Here we estimate the limits of these natural energy conversions and the extent to which these can be used as renewable energy sources using the laws of thermodynamics. At most, wind power in the order of 1 000 TW (1 TW = 1E12 W) can be derived from the total flux of incoming solar radiation of 175 000 TW, which is consistent with estimates based on observations. Other generation rates that are derived from the kinetic energy of wind are in the order of 10-100 TW. In comparison, the human primary energy demand of about 17 TW constitutes a considerable fraction of these rates. We provide some further analysis on the limits of wind power using a combination of conceptual models, observational data, and numerical simulation models. We find that many current estimates of wind power substantially overestimate the potential of wind power because the effect of kinetic energy extraction on the air flow is neglected. We conclude that the only form of renewable energy that is available in substantial amounts and that is associated with minor climatic impacts is solar power.

  1. The Effect of Electric Load Profiles on the Performance of Off-Grid Residential Hybrid Renewable Energy Systems

    OpenAIRE

    Stephen Treado

    2015-01-01

    This paper investigates the energy performance of off-grid residential hybrid renewable electric power systems, particularly the effect of electric load profiles on the ability to harvest available solar energy and avoid the consumption of auxiliary energy in the form of propane. The concepts are illustrated by an analysis of the energy performance of electric and propane-fired refrigerators. Off-grid electric power systems frequently incorporate a renewable source, such as wind or solar phot...

  2. WAMS Based Intelligent Operation and Control of Modern Power System with large Scale Renewable Energy Penetration

    DEFF Research Database (Denmark)

    Rather, Zakir Hussain

    for alternative energy systems driven by the pressure to reduce carbon emission has stimulated a renewal of interest in wind power. The combined effect of growing demand and increasing level of intermittent wind energy penetration coupled with deregulated market has pushed the power system to operate...... and protection of complex power systems. WAMS is rapidly being implemented in power systems across the globe and is seen a means to realize smart grid at transmission system level. This thesis (industrial PhD with kk-electronic) proposes WAMS based methods to intelligently control and operate large...... other ongoing projects, priority of substations and scheduled/unscheduled maintenance. New solution to address few of the practical issues in WAMS experienced on real life Western Danish power system have also been proposed. The overall WAMS has been implemented in DigSILENT and applied to the Western...

  3. A Low Cost Concept for Data Acquisition Systems Applied to Decentralized Renewable Energy Plants

    Directory of Open Access Journals (Sweden)

    Fábio T. Brito

    2011-01-01

    Full Text Available The present paper describes experiences of the use of monitoring and data acquisition systems (DAS and proposes a new concept of a low cost DAS applied to decentralized renewable energy (RE plants with an USB interface. The use of such systems contributes to disseminate these plants, recognizing in real time local energy resources, monitoring energy conversion efficiency and sending information concerning failures. These aspects are important, mainly for developing countries, where decentralized power plants based on renewable sources are in some cases the best option for supplying electricity to rural areas. Nevertheless, the cost of commercial DAS is still a barrier for a greater dissemination of such systems in developing countries. The proposed USB based DAS presents a new dual clock operation philosophy, in which the acquisition system contains two clock sources for parallel information processing from different communication protocols. To ensure the low cost of the DAS and to promote the dissemination of this technology in developing countries, the proposed data acquisition firmware and the software for USB microcontrollers programming is a free and open source software, executable in the Linux and Windows® operating systems.

  4. A low cost concept for data acquisition systems applied to decentralized renewable energy plants.

    Science.gov (United States)

    Jucá, Sandro C S; Carvalho, Paulo C M; Brito, Fábio T

    2011-01-01

    The present paper describes experiences of the use of monitoring and data acquisition systems (DAS) and proposes a new concept of a low cost DAS applied to decentralized renewable energy (RE) plants with an USB interface. The use of such systems contributes to disseminate these plants, recognizing in real time local energy resources, monitoring energy conversion efficiency and sending information concerning failures. These aspects are important, mainly for developing countries, where decentralized power plants based on renewable sources are in some cases the best option for supplying electricity to rural areas. Nevertheless, the cost of commercial DAS is still a barrier for a greater dissemination of such systems in developing countries. The proposed USB based DAS presents a new dual clock operation philosophy, in which the acquisition system contains two clock sources for parallel information processing from different communication protocols. To ensure the low cost of the DAS and to promote the dissemination of this technology in developing countries, the proposed data acquisition firmware and the software for USB microcontrollers programming is a free and open source software, executable in the Linux and Windows® operating systems. PMID:22346600

  5. Optimal unit sizing of a hybrid renewable energy system for isolated applications

    International Nuclear Information System (INIS)

    In general, the methods used to conceive a renewable energy production system overestimate the size of the generating units. These methods increase the investment cost and the production cost of energy. The work presented in this thesis proposes a methodology to optimally size a renewable energy system.- This study shows that the classic approach based only on a long term analysis of system's behaviour is not sufficient and a complementary methodology based on a short term analysis is proposed. A numerical simulation was developed in which the mathematical models of the solar panel, the wind turbines and battery are integrated. The daily average solar energy per m2 is decomposed into a series of hourly I energy values using the Collares-Pereira equations. The time series analysis of the wind speed is made using the Monte Carlo Simulation Method. The second part of this thesis makes a detailed analysis of an isolated wind energy production system. The average energy produced by the system depends on the generator's rated power, the total swept area of the wind turbine, the gearbox's transformation ratio, the battery voltage and the wind speed probability function. The study proposes a methodology to determine the optimal matching between the rated power of the permanent magnet synchronous machine and the wind turbine's rotor size. This is made taking into account the average electrical energy produced over a period of time. (author)

  6. Renewable energy information system on Internet - REISI; Renewable Energy Information System on Internet - REISI. Produktinformationen und Betriebsergebnisse solarer Energieversorgungssysteme im Internet

    Energy Technology Data Exchange (ETDEWEB)

    Rohrig, K. [Institut fuer Solare Energieversorgungstechnik (ISET), Kassel (Germany)

    1998-12-01

    Since 1988, ISET, supported by the Government of the German Land Hesse, has been operating an information system for components of solar energy supply plants (ISEE). In this online databank there are at present technical data, cost data and manufacturers` information on wind energy plants, photo-voltaic modules, solar collectors, inverters, rectifiers and batteries. The ISEE contains over 4800 data sentences, of which about 3,300 data sentences are more recent than 3 years old. In addition there are about 600 addresses of manufacturers, distributors and suppliers. With this offer, the ISEE is the leading supplier in Germany of information in the area of components for solar energy supply systems. [Deutsch] Seit 1988 betreibt das ISET, gefoerdert durch die hessische Landesregierung, ein Informationssystem fuer Komponenten solarer Energieversorgungsanlagen (ISEE). Aktuell stehen in dieser Online-Datenbank technische Daten, Kostendaten sowie Herstellerinformationen zu Windenergieanlagen, Photovoltaikmodulen, Solarkollektoren, Stromrichtern, Gleichstromstellern und Batterien zur Verfuegung. Das ISEE enthaelt ueber 4.800 Datensaetze, davon sind ca. 3.300 Datensaetze juenger als 3 Jahre. Hinzu kommen etwa 600 Adressen von Herstellern, Distributoren und Lieferanten. Mit diesem Angebot ist das ISEE in Deutschland fuehrender Informationsanbieter im Bereich Komponenten solarer Energieversorgungssysteme. Aufbauend auf den Datenbestand der Online-Informationssysteme WISY und ISEE sowie auf den Auswertungen des WMEP wurde im September 1997 der Technologiebereich Windenergie im `Renewable Energy Information System on Internet - REISI` fertiggestellt. (orig./RHM)

  7. Sox17 expression confers self-renewal potential and fetal stem cell characteristics upon adult hematopoietic progenitors

    OpenAIRE

    He, Shenghui; Kim, Injune; Lim, Megan S.; Morrison, Sean J

    2011-01-01

    A key question concerns the mechanisms that determine temporal identity in stem cells. Fetal hematopoietic stem cells (HSCs) differ from adult HSCs in terms of gene expression profile, surface marker expression, differentiation, and self-renewal capacity. We previously showed that the transcription factor SOX17 is expressed by fetal, but not adult, HSCs and is required for the maintenance of fetal and neonatal, but not adult, HSCs. In the current study, we show that ectopic expression of Sox1...

  8. Self-Renewing Pten-/-TP53-/- Protospheres Produce Metastatic Adenocarcinoma Cell Lines with Multipotent Progenitor Activity

    OpenAIRE

    Abou-Kheir, Wassim; Hynes, Paul G.; Martin, Philip; Yin, Juan Juan; Liu, Yen-Nien; Seng, Victoria; Lake, Ross; Spurrier, Joshua; Kelly, Kathleen

    2011-01-01

    Prostate cancers of luminal adenocarcinoma histology display a range of clinical behaviors. Although most prostate cancers are slow-growing and indolent, a proportion is aggressive, developing metastasis and resistance to androgen deprivation treatment. One hypothesis is that a portion of aggressive cancers initiate from stem-like, androgen-independent tumor-propagating cells. Here we demonstrate the in vitro creation of a mouse cell line, selected for growth as self-renewing stem/progenitor ...

  9. Multilineage Potential and Self-Renewal Define an Epithelial Progenitor Cell Population in the Adult Thymus

    Directory of Open Access Journals (Sweden)

    Kahlia Wong

    2014-08-01

    Full Text Available Thymic epithelial cells (TECs are critical for T cell development and self-tolerance but are gradually lost with age. The existence of thymic epithelial progenitors (TEPCs in the postnatal thymus has been inferred, but their identity has remained enigmatic. Here, we assessed the entire adult TEC compartment in order to reveal progenitor capacity is retained exclusively within a subset of immature thymic epithelium displaying several hallmark features of stem/progenitor function. These adult TEPCs generate mature cortical and medullary lineages in a stepwise fashion, including Aire+ TEC, within fetal thymus reaggregate grafts. Although relatively quiescent in vivo, adult TEPCs demonstrate significant in vitro colony formation and self-renewal. Importantly, 3D-cultured TEPCs retain their capacity to differentiate into cortical and medullary TEC lineages when returned to an in vivo thymic microenvironment. No other postnatal TEC subset exhibits this combination of properties. The characterization of adult TEPC will enable progress in understanding TEC biology in aging and regeneration.

  10. Soft substrates promote homogeneous self-renewal of embryonic stem cells via downregulating cell-matrix tractions.

    Directory of Open Access Journals (Sweden)

    Farhan Chowdhury

    Full Text Available Maintaining undifferentiated mouse embryonic stem cell (mESC culture has been a major challenge as mESCs cultured in Leukemia Inhibitory Factor (LIF conditions exhibit spontaneous differentiation, fluctuating expression of pluripotency genes, and genes of specialized cells. Here we show that, in sharp contrast to the mESCs seeded on the conventional rigid substrates, the mESCs cultured on the soft substrates that match the intrinsic stiffness of the mESCs and in the absence of exogenous LIF for 5 days, surprisingly still generated homogeneous undifferentiated colonies, maintained high levels of Oct3/4, Nanog, and Alkaline Phosphatase (AP activities, and formed embryoid bodies and teratomas efficiently. A different line of mESCs, cultured on the soft substrates without exogenous LIF, maintained the capacity of generating homogeneous undifferentiated colonies with relatively high levels of Oct3/4 and AP activities, up to at least 15 passages, suggesting that this soft substrate approach applies to long term culture of different mESC lines. mESC colonies on these soft substrates without LIF generated low cell-matrix tractions and low stiffness. Both tractions and stiffness of the colonies increased with substrate stiffness, accompanied by downregulation of Oct3/4 expression. Our findings demonstrate that mESC self-renewal and pluripotency can be maintained homogeneously on soft substrates via the biophysical mechanism of facilitating generation of low cell-matrix tractions.

  11. Environmental oxygen tension regulates the energy metabolism and self-renewal of human embryonic stem cells.

    Directory of Open Access Journals (Sweden)

    Catherine E Forristal

    Full Text Available Energy metabolism is intrinsic to cell viability but surprisingly has been little studied in human embryonic stem cells (hESCs. The current study aims to investigate the effect of environmental O2 tension on carbohydrate utilisation of hESCs. Highly pluripotent hESCs cultured at 5% O2 consumed significantly more glucose, less pyruvate and produced more lactate compared to those maintained at 20% O2. Moreover, hESCs cultured at atmospheric O2 levels expressed significantly less OCT4, SOX2 and NANOG than those maintained at 5% O2. To determine whether this difference in metabolism was a reflection of the pluripotent state, hESCs were cultured at 5% O2 in the absence of FGF2 for 16 hours leading to a significant reduction in the expression of SOX2. In addition, these cells consumed less glucose and produced significantly less lactate compared to those cultured in the presence of FGF2. hESCs maintained at 5% O2 were found to consume significantly less O2 than those cultured in the absence of FGF2, or at 20% O2. GLUT1 expression correlated with glucose consumption and using siRNA and chromatin immunoprecipitation was found to be directly regulated by hypoxia inducible factor (HIF-2α at 5% O2. In conclusion, highly pluripotent cells associated with hypoxic culture consume low levels of O2, high levels of glucose and produce large amounts of lactate, while at atmospheric conditions glucose consumption and lactate production are reduced and there is an increase in oxidative metabolism. These data suggest that environmental O2 regulates energy metabolism and is intrinsic to the self-renewal of hESCs.

  12. The PI3K Pathway Balances Self-Renewal and Differentiation of Nephron Progenitor Cells through β-Catenin Signaling

    Directory of Open Access Journals (Sweden)

    Nils Olof Lindström

    2015-04-01

    Full Text Available Nephron progenitor cells differentiate to form nephrons during embryonic kidney development. In contrast, self-renewal maintains progenitor numbers and premature depletion leads to impaired kidney function. Here we analyze the PI3K pathway as a point of convergence for the multiple pathways that are known to control self-renewal in the kidney. We demonstrate that a reduction in PI3K signaling triggers premature differentiation of the progenitors and activates a differentiation program that precedes the mesenchymal-to-epithelial transition through ectopic activation of the β-catenin pathway. Therefore, the combined output of PI3K and other pathways fine-tunes the balance between self-renewal and differentiation in nephron progenitors.

  13. Sevoflurane inhibits the self-renewal of mouse embryonic stem cells via the GABAAR-ERK signaling pathway.

    Science.gov (United States)

    Yang, Liuqing; Ge, Yali; Lin, Shunyan; Fang, Xiangzhi; Zhou, Loujing; Gao, Ju

    2016-09-01

    A large number of pregnant women are exposed to inhalation anesthetics for non‑obstetric surgery. Previous studies have demonstrated the toxicity to the developing fetus caused by the inhalation anesthetic sevoflurane, which can permeate rapidly through the placental barrier. However, the mechanism of embryotoxicity remains largely unknown. The present study used mouse embryonic stem cells (mES cells) as an early development model, in order to investigate the mechanism underlying the embryo toxicity of sevoflurane and found that sevoflurane inhibited the self‑renewal of mES cells. Sevoflurane was shown to upregulate the level of phosphorylated extracellular signal‑regulated kinase (p‑ERK) but it did not affect the total expression of ERK by γ-aminobutyric acid A receptor (GABAAR). Knockdown of the GABAAR rescued the upregulation of p‑ERK and inhibition of self‑renewal induced by sevoflurane in mES cells. Additionally, inhibition of the activity of ERK signaling can rescue the influence of sevoflurane on mES cells. In conclusion, sevoflurane inhibited the self‑renewal of mES cells by GABAAR/ERK signaling, which may be a potential therapeutic target to prevent the embryotoxicity of sevoflurane. PMID:27431564

  14. Cell Surface Display Fungal Laccase as a Renewable Biocatalyst for Degradation of Persistent Micropollutants Bisphenol A and Sulfamethoxazole.

    Science.gov (United States)

    Chen, Yingying; Stemple, Brooke; Kumar, Manish; Wei, Na

    2016-08-16

    Fungal laccases have high activity in degrading various persistent organic pollutants. However, using enzymes in solution for water treatment has limitations of nonreusability, short enzyme lifetimes, and high cost of single use. In this study, we developed a new type of biocatalyst by immobilizing fungal laccase on the surface of yeast cells using synthetic biology techniques. The biocatalyst, referred to as surface display laccase (SDL), had an enzyme activity of 104 ± 3 mU/g dry cell (with 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonate (ABTS)). The SDL retained over 90% of the initial enzyme activity after 25 days storage at room temperature, while, in contrast, activity of free laccase declined to 60% of its initial activity. The SDL could be reused with high stability as it retained 74% of initial activity after eight repeated batch reactions. Proof-of-concept evaluations of the effectiveness of SDL in treating contaminants of emerging concern were performed with bisphenol A and sulfamethoxazole. Results from contaminant degradation kinetics and the effects of redox mediator amendment provided insights into the factors affecting the efficacy of the SDL system. This study reports, for the first time, the development of a surface display enzyme biocatalyst as an effective and renewable alternative for treating recalcitrant organic micropollutants. PMID:27414990

  15. Thermoeconomic Optimization of a Renewable Polygeneration System Serving a Small Isolated Community

    Directory of Open Access Journals (Sweden)

    Francesco Calise

    2015-01-01

    Full Text Available During the last years, special attention has been paid to renewable polygeneration technologies, able of simultaneously producing thermal, cooling, electrical energy and desalinated water from seawater. This paper focuses on an innovative polygeneration system driven by renewable energy sources, including the following technologies: hybrid photovoltaic/thermal collectors, concentrating parabolic trough (CPVT, a biomass heater, a single-stage absorption chiller and a multiple-effect distillation desalination system. The system is designed to cover the base load of an isolated small community. In previous papers, the dynamic simulation model about plant operation is discussed. In this paper, a detailed exergy, economic and environmental analysis of the plant is presented. In addition, the plant was optimized using different objective functions, applying the Design of Experiment (DoE methodology which evaluates the sensitivity of the different objective functions with respect to the selected design parameters. The results show that an increase of the storage volume is generally negative, whereas increasing the solar field area involves an increase of the exergy destruction rate, but also an improvement of the CPVT exergy output provided; the final result is an increase of both the exergy efficiency and the economic profitability of the polygeneration system.

  16. A Power Supply System with ZVS and Current-Doubler Features for Hybrid Renewable Energy Conversion

    Directory of Open Access Journals (Sweden)

    Jye-Chau Su

    2013-09-01

    Full Text Available In this paper, a power supply system for hybrid renewable energy conversion is proposed, which can process PV (photovoltaic power and wind-turbine energy simultaneously for step-down voltage and high current applications. It is a dual-input converter and mainly contains a PV energy source, a wind turbine energy source, a zero-voltage-switching (ZVS forward converter, and a current-doubler rectifier. The proposed power supply system has the following advantages: (1 PV-arrays and wind-energy sources can alternatively deliver power to the load during climate or season alteration; (2 maximum power point tracking (MPPT can be accomplished for both different kinds of renewable-energy sources; (3 ZVS and synchronous rectification techniques for the active switches of the forward converter are embedded so as to reduce switching and conducting losses; and (4 electricity isolation is naturally obtained. To achieve an optimally dynamic response and to increase control flexibility, a digital signal processor (DSP is investigated and presented to implement MPPT algorithm and power regulating scheme. Finally, a 240 W prototype power supply system with ZVS and current-doubler features to deal with PV power and wind energy is built and implemented. Experimental results are presented to verify the performance and the feasibility of the proposed power supply system.

  17. A Measurement and Power Line Communication System Design for Renewable Smart Grids

    Science.gov (United States)

    Kabalci, E.; Kabalci, Y.

    2013-10-01

    The data communication over the electric power lines can be managed easily and economically since the grid connections are already spread around all over the world. This paper investigates the applicability of Power Line Communication (PLC) in an energy generation system that is based on photovoltaic (PV) panels with the modeling study in Matlab/Simulink. The Simulink model covers the designed PV panels, boost converter with Perturb and Observe (P&O) control algorithm, full bridge inverter, and the binary phase shift keying (BPSK) modem that is utilized to transfer the measured data over the power lines. This study proposes a novel method to use the electrical power lines not only for carrying the line voltage but also to transmit the measurements of the renewable energy generation plants. Hence, it is aimed at minimizing the additional monitoring costs such as SCADA, Ethernet-based or GSM based systems by using the proposed technique. Although this study is performed with solar power plants, the proposed model can be applied to other renewable generation systems. Consequently, the usage of the proposed technique instead of SCADA or Ethernet-based systems eliminates additional monitoring costs.

  18. An Innovative Use of Renewable Ground Heat for Insulation in Low Exergy Building Systems

    Directory of Open Access Journals (Sweden)

    Hansjürg Leibundgut

    2012-08-01

    Full Text Available Ground heat is a renewable resource that is readily available for buildings in cool climates, but its relatively low temperature requires the use of a heat pump to extract it for heating. We developed a system that uses low temperature ground heat directly in a building wall to reduce transmission heat losses. The Active Low Exergy Geothermal Insulation Systems (ALEGIS minimizes exergy demand and maximizes the use of renewable geothermal heat from the ground. A fluid is pumped into a small pipe network in an external layer of a wall construction that is linked to a ground heat source. This decouples the building from the outside temperature, therefore eliminating large peak demands and reducing the primary energy demand. Our steady-state analysis shows that at a design temperature of −10 °C the 6 cm thick active insulation system has equivalent performance to 11 cm of passive insulation. Our comparison of heating performance of a building with our active insulation system versus a building with static insulation of the same thickness shows a 15% reduction in annual electricity demand, and thus exergy input. We present an overview of the operation and analysis of our low exergy concept and its modeled performance.

  19. The B-MYB transcriptional network guides cell cycle progression and fate decisions to sustain self-renewal and the identity of pluripotent stem cells.

    Directory of Open Access Journals (Sweden)

    Ming Zhan

    Full Text Available Embryonic stem cells (ESCs are pluripotent and have unlimited self-renewal capacity. Although pluripotency and differentiation have been examined extensively, the mechanisms responsible for self-renewal are poorly understood and are believed to involve an unusual cell cycle, epigenetic regulators and pluripotency-promoting transcription factors. Here we show that B-MYB, a cell cycle regulated phosphoprotein and transcription factor critical to the formation of inner cell mass, is central to the transcriptional and co-regulatory networks that sustain normal cell cycle progression and self-renewal properties of ESCs. Phenotypically, B-MYB is robustly expressed in ESCs and induced pluripotent stem cells (iPSCs, and it is present predominantly in a hypo-phosphorylated state. Knockdown of B-MYB results in functional cell cycle abnormalities that involve S, G2 and M phases, and reduced expression of critical cell cycle regulators like ccnb1 and plk1. By conducting gene expression profiling on control and B-MYB deficient cells, ChIP-chip experiments, and integrative computational analyses, we unraveled a highly complex B-MYB-mediated transcriptional network that guides ESC self-renewal. The network encompasses critical regulators of all cell cycle phases and epigenetic regulators, pluripotency transcription factors, and differentiation determinants. B-MYB along with E2F1 and c-MYC preferentially co-regulate cell cycle target genes. B-MYB also co-targets genes regulated by OCT4, SOX2 and NANOG that are significantly associated with stem cell differentiation, embryonic development, and epigenetic control. Moreover, loss of B-MYB leads to a breakdown of the transcriptional hierarchy present in ESCs. These results coupled with functional studies demonstrate that B-MYB not only controls and accelerates cell cycle progression in ESCs it contributes to fate decisions and maintenance of pluripotent stem cell identity.

  20. Planning renewable energy systems as part of Cradle-to-Cradle thinking on islands

    OpenAIRE

    Smink, Carla; Hong, Lixuan; Kerndrup, Søren; Sperling, Karl; Möller, Bernd

    2010-01-01

    In a recently started EU Interreg IVB project ‘Cradle to Cradle Islands’, the cradle-to-cradle concept is going to be applied to a number of islands in the North Sea region, aiming at 100% renewable energy supply. The transformation of island energy systems is a challenging task, although islands such as Samsø in Denmark have shown the way. While technologies exist and are readily available on the market to produce electricity and heat and to provide mobility, the difficulties typically lie i...

  1. Development of Mixed Autonomous Power System on the Basis of Renewable Energy Sources

    Directory of Open Access Journals (Sweden)

    D. P. Laoshvili

    2010-01-01

    Full Text Available A principal circuit diagram has been developed for an autonomous power system on the basis of renewable energy sources – solar and accumulator batteries.Due to the usage of a dc pulse converter, a dc converter (interrupter, an IGBT module inverter and a single-phase matching power transformer it is possible to achieve an effective sectioning of constant voltage and their inversion with minimal energy losses.Efficiency factor of the proposed converter installation exceeds 90 % and power factor is close to unity.

  2. A planarian p53 homolog regulates proliferation and self-renewal in adult stem cell lineages

    OpenAIRE

    Pearson, Bret J.; Alvarado, Alejandro Sánchez

    2010-01-01

    The functions of adult stem cells and tumor suppressor genes are known to intersect. However, when and how tumor suppressors function in the lineages produced by adult stem cells is unknown. With a large population of stem cells that can be manipulated and studied in vivo, the freshwater planarian is an ideal system with which to investigate these questions. Here, we focus on the tumor suppressor p53, homologs of which have no known role in stem cell biology in any invertebrate examined thus ...

  3. Mobilisation of the potential for the renewal of energy systems in existing buildings; Mobilisierung der energetischen Erneuerungspotenziale im Wohnbaubestand

    Energy Technology Data Exchange (ETDEWEB)

    Ott, W.; Baur, M.; Kaufmann, Y. [econcept AG, Zuerich (Switzerland); Jakob, M.; Ott, A. [Centre for Energy Policy and Economics (CEPE), ETH Zuerich, Zuerich (Switzerland)

    2005-07-01

    This comprehensive report for the Swiss Federal Office of Energy (SFOE) summarises the findings of an energy-policy project that looked into the potential for the renewal of energy systems in existing buildings. The report presents an analysis of the situation as far as buildings, their ownership and the development of renovation work is concerned. Also, the results of a survey made under the owners of buildings and managers of real estate with respect to building renovation aspects are presented and discussed. Further, an analysis of problems arising from deficits in the renewal of energy-relevant components is provided and background and motivation for the renewal of buildings are looked at. Also, economic aspects and sustainability issues are considered. A further chapter covers strategies and measures that can be used to mobilise the renewal potential, including legislature and labelling systems.

  4. Renewable Energy and Hydrogen System Concepts for Remote Communities in the West Nordic Region

    Energy Technology Data Exchange (ETDEWEB)

    Ulleberg, Oeystein; Moerkved, Andreas

    2008-02-25

    In 2003 the Nordic Council of Ministers granted the funding for the first of several studies on renewable energy and hydrogen (RE/H2) energy systems for remote communities in the West Nordic region. The objective with this report is to summarize the main findings from Phase II and III of the West Nordic project. The island Nolsoy, Faroe Islands, was selected as a case study. The main conclusion is that it makes sense to design a wind/diesel-system with thermal storage, both from a techno-economical and environmental point of view. Such systems can have close to 100% local utilization of the wind energy, and can cover up to 75% of the total annual electricity demand and 35% of the annual heat demand at a cost of energy around 0.07 - 0.09 euro/kWh. The introduction of a hydrogen system is technically feasible, but doubles the overall investment costs

  5. Energy, exergy and sustainability analyses of hybrid renewable energy based hydrogen and electricity production and storage systems: Modeling and case study

    International Nuclear Information System (INIS)

    In this study, hybrid renewable energy based hydrogen and electricity production and storage systems are conceptually modeled and analyzed in detail through energy, exergy and sustainability approaches. Several subsystems, namely hybrid geothermal energy-wind turbine-solar photovoltaic (PV) panel, inverter, electrolyzer, hydrogen storage system, Proton Exchange Membrane Fuel Cell (PEMFC), battery and loading system are considered. Also, a case study, based on hybrid wind–solar renewable energy system, is conducted and its results are presented. In addition, the dead state temperatures are considered as 0 °C, 10 °C, 20 °C and 30 °C, while the environment temperature is 30 °C. The maximum efficiencies of the wind turbine, solar PV panel, electrolyzer, PEMFC are calculated as 26.15%, 9.06%, 53.55%, and 33.06% through energy analysis, and 71.70%, 9.74%, 53.60%, and 33.02% through exergy analysis, respectively. Also, the overall exergy efficiency, ranging from 5.838% to 5.865%, is directly proportional to the dead state temperature and becomes higher than the corresponding energy efficiency of 3.44% for the entire system. -- Highlights: ► Developing a three-hybrid renewable energy (geothermal–wind–solar)-based system. ► Undertaking a parametric study at various dead state temperatures. ► Investigating the effect of dead state temperatures on exergy efficiency

  6. A single-phase nine-level inverter for renewable energy systems employing model predictive control

    International Nuclear Information System (INIS)

    Highlights: • A nine-level inverter for renewable energy applications is investigated. • We have developed a model predictive controller enabling fast dynamic response. • Separate DC-link voltage regulation and neutral point potential balance are attained. • Asymmetric conditions in terms of solar radiation and voltage variation are tested. • System performance is validated by an experimental setup of 2 individual PV strings. - Abstract: In this paper a single-phase cascaded Multilevel Inverter (MI) consisting of full NPC bridges for renewable energy systems is investigated. The development of the introduced control strategy is based on the application of Model Predictive Control (MPC) technique meeting the required specifications of the individual voltage level regulation of each separate DC source and neutral point potential balance under unity power factor. Illustrating the effectiveness of the developed controller, two separate PV strings are controlled while being subject to transient phenomena related to asymmetric string conditions in terms of solar radiation and reference voltage variation. The inverter topology of full NPC bridges in cascade allows low current THD factor to be achieved using a simple inductor instead of complicated LCL filters benefiting also from low capacitor banks in the DC-link bus. The proposed MPC performance has been validated by experiments carried out on a cascaded MI topology delivering power from two separate PV system strings

  7. Development of Nuclear Renewable Oil Shale Systems for Flexible Electricity and Reduced Fossil Fuel Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Daniel Curtis; Charles Forsberg; Humberto Garcia

    2015-05-01

    We propose the development of Nuclear Renewable Oil Shale Systems (NROSS) in northern Europe, China, and the western United States to provide large supplies of flexible, dispatchable, very-low-carbon electricity and fossil fuel production with reduced CO2 emissions. NROSS are a class of large hybrid energy systems in which base-load nuclear reactors provide the primary energy used to produce shale oil from kerogen deposits and simultaneously provide flexible, dispatchable, very-low-carbon electricity to the grid. Kerogen is solid organic matter trapped in sedimentary shale, and large reserves of this resource, called oil shale, are found in northern Europe, China, and the western United States. NROSS couples electricity generation and transportation fuel production in a single operation, reduces lifecycle carbon emissions from the fuel produced, improves revenue for the nuclear plant, and enables a major shift toward a very-low-carbon electricity grid. NROSS will require a significant development effort in the United States, where kerogen resources have never been developed on a large scale. In Europe, however, nuclear plants have been used for process heat delivery (district heating), and kerogen use is familiar in certain countries. Europe, China, and the United States all have the opportunity to use large scale NROSS development to enable major growth in renewable generation and either substantially reduce or eliminate their dependence on foreign fossil fuel supplies, accelerating their transitions to cleaner, more efficient, and more reliable energy systems.

  8. Production of Hydrogen for Clean and Renewable Source of Energy for Fuel Cell Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xunming; Ingler, William B, Jr.; Abraham, Martin; Castellano, Felix; Coleman, Maria; Collins, Robert; Compaan, Alvin; Giolando, Dean; Jayatissa, Ahalapitiya. H.; Stuart, Thomas; Vonderembse, Mark

    2008-10-31

    This was a two-year project that had two major components: 1) the demonstration of a PV-electrolysis system that has separate PV system and electrolysis unit and the hydrogen generated is to be used to power a fuel cell based vehicle; 2) the development of technologies for generation of hydrogen through photoelectrochemical process and bio-mass derived resources. Development under this project could lead to the achievement of DOE technical target related to PEC hydrogen production at low cost. The PEC part of the project is focused on the development of photoelectrochemical hydrogen generation devices and systems using thin-film silicon based solar cells. Two approaches are taken for the development of efficient and durable photoelectrochemical cells; 1) An immersion-type photoelectrochemical cells (Task 3) where the photoelectrode is immersed in electrolyte, and 2) A substrate-type photoelectrochemical cell (Task 2) where the photoelectrode is not in direct contact with electrolyte. Four tasks are being carried out: Task 1: Design and analysis of DC voltage regulation system for direct PV-to-electrolyzer power feed Task 2: Development of advanced materials for substrate-type PEC cells Task 3: Development of advanced materials for immersion-type PEC cells Task 4: Hydrogen production through conversion of biomass-derived wastes

  9. Renewable Energy Systems: Development and Perspectives of a Hybrid Solar-Wind System

    Directory of Open Access Journals (Sweden)

    C. Shashidhar

    2012-02-01

    Full Text Available Considering the intermittent natural energy resources and the seasonal un-balance, a phtovoltaic-wind hybrid electrical power supply system was developed to accommodate remote locations where a conventional grid connection is inconvenient or expensive. However, the hybrid system can also be applied with grid connection and owners are allowed to sell excessive power back to the electric utility. The proposed set-up consists of a photo-voltaic solar-cell array, a mast mounted wind generator, lead-acid storage batteries, an inverter unit to convert DC to AC, electrical lighting loads, electrical heating loads, several fuse and junction boxes and associated wiring, and test instruments for measuring voltages, currents, power factors, and harmonic contamination data throughout the system. The proposed hybrid solar-wind power generating system can be extensively used to illustrate electrical concepts in hands-on laboratories and also for demonstrations in the Industrial Technology curriculum. This paper describes an analysis of local PV-wind hybrid systems for supplying electricity to a private house, farmhouse or small company with electrical power depending on the site needs. The major system components, work principle and specific working condition are presented.

  10. Stochastic simulation of power systems with integrated renewable and utility-scale storage resources

    Science.gov (United States)

    Degeilh, Yannick

    The push for a more sustainable electric supply has led various countries to adopt policies advocating the integration of renewable yet variable energy resources, such as wind and solar, into the grid. The challenges of integrating such time-varying, intermittent resources has in turn sparked a growing interest in the implementation of utility-scale energy storage resources ( ESRs), with MWweek storage capability. Indeed, storage devices provide flexibility to facilitate the management of power system operations in the presence of uncertain, highly time-varying and intermittent renewable resources. The ability to exploit the potential synergies between renewable and ESRs hinges on developing appropriate models, methodologies, tools and policy initiatives. We report on the development of a comprehensive simulation methodology that provides the capability to quantify the impacts of integrated renewable and ESRs on the economics, reliability and emission variable effects of power systems operating in a market environment. We model the uncertainty in the demands, the available capacity of conventional generation resources and the time-varying, intermittent renewable resources, with their temporal and spatial correlations, as discrete-time random processes. We deploy models of the ESRs to emulate their scheduling and operations in the transmission-constrained hourly day-ahead markets. To this end, we formulate a scheduling optimization problem (SOP) whose solutions determine the operational schedule of the controllable ESRs in coordination with the demands and the conventional/renewable resources. As such, the SOP serves the dual purpose of emulating the clearing of the transmission-constrained day-ahead markets (DAMs ) and scheduling the energy storage resource operations. We also represent the need for system operators to impose stricter ramping requirements on the conventional generating units so as to maintain the system capability to perform "load following'', i

  11. Proceedings of the 2009 CIGRE Canada conference on power systems : innovation and renewal : building the new power system

    International Nuclear Information System (INIS)

    The Conseil International des Grands Reseaux Electriques (CIGRE) is the International Council on Large Electric Systems. It promotes technical, economic and environmental developments in electricity transmission and generation. CIGRE Canada is the Canadian National Committee which fosters the participation of Canadian members in CIGRE activities. CIGRE Canada organizes an annual conference that provides a forum for power system engineers, decision makers,economists, and academics to discuss technological developments in electrical power systems. The presentations at this conference addressed issues regarding the use of renewable energy sources in power transmission and distribution systems, with particular reference to control and protection; HVDC and MVDC; modelling tools; interface technologies; and reduced carbon generation and sustainability. The use of active distribution systems was also discussed in terms of future trends; the role of information technology and communications; and the role of energy storage. The session on smart grids addressed issues such as power utility perspectives; sensing, measurements and controls; advanced interfaces and decision support systems; open-architecture; distributed energy resources; and regulatory issues. Issues concerning the interconnection of non traditional energy sources to the power systems were also discussed along with recent research initiatives related to renewable energy source development. The sessions were entitled: smart grids; distributed energy resources; wind and solar PV; AC systems and HV lines; wide area measurements; power system operation and control; modelling and analysis; substation automation; and HVDC and facts. The conference featured 66 presentations, of which 35 have been catalogued separately for inclusion in this database

  12. Hydro Solar 21- A building energetic demand providing system based on renewable energies and hydrogen; Hydro Solar 21- Energias renovables e hidrogeno para el abastecimiento energetico de un edificio

    Energy Technology Data Exchange (ETDEWEB)

    Renilla Collado, R.; Ortega Izquierdo, M.

    2008-07-01

    Hydro Solar 21 is an energy innovation Project carried out in Burgos City to develop an energy production system based on renewable energies to satisfy light and air condition requirements of a restored building. Nocturnal light demand is satisfied with hydrogen consumption in fuel cells. This hydrogen is produced with an energy renewable system made up of two wind turbine generators and a photovoltaic system. The air conditioning demand is satisfied with an adsorption solar system which produces cold water using thermal solar energy. (Author) 8 refs.

  13. Ligand-independent androgen receptors promote ovarian teratocarcinoma cell growth by stimulating self-renewal of cancer stem/progenitor cells

    OpenAIRE

    Wei-Min Chung; Wei-Chun Chang; Lumin Chen; Tze-Yi Lin; Liang-Chi Chen; Yao-Ching Hung; Wen-Lung Ma

    2014-01-01

    Background: Ovarian teratocarcinoma (OVTC) arises from germ cells and contains a high percentage of cancer stem/progenitor cells (CSPCs), which promote cancer development through their ability to self-renew. Androgen and androgen receptor (androgen/AR) signaling has been reported to participate in cancer stemness in some types of cancer; however, this phenomenon has never been studied in OVTC. Methods: Ovarian teratocarcinoma cell line PA1 was manipulated to overexpress or knockdown AR by ...

  14. Dynamic cell culture system (7-IML-1)

    Science.gov (United States)

    Cogoli, Augusto

    1992-01-01

    This experiment is one of the Biorack experiments being flown on the International Microgravity Laboratory 1 (MIL-1) mission as part of an investigation studying cell proliferation and performance in space. One of the objectives of this investigation is to assess the potential benefits of bioprocessing in space with the ultimate goal of developing a bioreactor for continuous cell cultures in space. This experiment will test the operation of an automated culture chamber that was designed for use in a Bioreactor in space. The device to be tested is called the Dynamic Cell Culture System (DCCS). It is a simple device in which media are renewed or chemicals are injected automatically, by means of osmotic pumps. This experiment uses four Type I/O experiment containers. One DCCS unit, which contains a culture chamber with renewal of medium and a second chamber without a medium supply fits in each container. Two DCCS units are maintained under zero gravity conditions during the on-orbit period. The other two units are maintained under 1 gh conditions in a 1 g centrifuge. The schedule for incubator transfer is given.

  15. Choosing The Right Technology - Optimized Design Of Renewable Supply Systems For Residential Houses

    DEFF Research Database (Denmark)

    Milan, Christian; Bojesen, Carsten; Nielsen, Mads Pagh

    2012-01-01

    based on mixed integer linear programming. The methodology chooses the right combination of technologies and sizes the components based on on-site weather data and expected consumption profiles. Through this approach the fluctuations of RES as well as the user behavior are taken into account already......The use of renewable energy sources (RES) has continuously increased throughout the last decade. In the residential building sector the trend goes towards energy supply systems based on multiple RES. This is mainly due to political requirements, governmental subsidies and fuel price development....... These systems not only require an optimal design with respect to the installed capacities but also the right choice in combining the available technologies assuring a cost-effective solution. The aim of this paper is to present an optimization methodology for residential on-site energy supply systems...

  16. A global renewable energy system: A modelling exercise in ETSAP/TIAM

    DEFF Research Database (Denmark)

    Føyn, Tullik Helene Ystanes; Karlsson, Kenneth Bernard; Balyk, Olexandr; Grohnheit, Poul Erik

    2011-01-01

    . Results from the modelling are global and regional energy consumption, emission of greenhouse gasses and thereby potential increase in global mean temperature. Furthermore, total system costs are compared to a reference scenario. Existing analysis with TIAM shows different ways of reaching the 2 °C target...... (increase in global mean temperature) and also how uncertainty on different factors influences the optimal solution. The main conclusion from existing analysis with TIAM is that the 2 °C target is possible to reach, but it will be expensive. Another very important point is that if uncertainty on the value......This paper aims to test the ETSAP2-TIAM global energy system model and to try out how far it can go towards a global 100% renewable energy system with the existing model database. This will show where limits in global resources are met and where limits in the data fed to the model until now are met...

  17. CXCR6, a newly defined biomarker of tissue-specific stem cell asymmetric self-renewal, identifies more aggressive human melanoma cancer stem cells.

    Directory of Open Access Journals (Sweden)

    Rouzbeh Taghizadeh

    Full Text Available A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells. Recent investigations of a variety of tumor types have shown that phenotypically identifiable and isolable subfractions of cells possess the tumor-forming ability. In the present paper, using two lineage-related human melanoma cell lines, primary melanoma line IGR39 and its metastatic derivative line IGR37, two main observations are reported. The first one is the first phenotypic evidence to support the origin of melanoma cancer stem cells (CSCs from mutated tissue-specific stem cells; and the second one is the identification of a more aggressive subpopulation of CSCs in melanoma that are CXCR6+.We defined CXCR6 as a new biomarker for tissue-specific stem cell asymmetric self-renewal. Thus, the relationship between melanoma formation and ABCG2 and CXCR6 expression was investigated. Consistent with their non-metastatic character, unsorted IGR39 cells formed significantly smaller tumors than unsorted IGR37 cells. In addition, ABCG2+ cells produced tumors that had a 2-fold greater mass than tumors produced by unsorted cells or ABCG2- cells. CXCR6+ cells produced more aggressive tumors. CXCR6 identifies a more discrete subpopulation of cultured human melanoma cells with a more aggressive MCSC phenotype than cells selected on the basis of the ABCG2+ phenotype alone.The association of a more aggressive tumor phenotype with asymmetric self-renewal phenotype reveals a previously unrecognized aspect of tumor cell physiology. Namely, the retention of some tissue-specific stem cell attributes, like the ability to asymmetrically self-renew, impacts the natural history of human tumor development. Knowledge of this new aspect of tumor development and progression may provide new targets for cancer prevention and treatment.

  18. TOWARDS A RESILIENT ENERGY SYSTEM IN EASTERN ROMANIA – FROM FOSSIL FUELS TO RENEWABLE SOURCES

    Directory of Open Access Journals (Sweden)

    BĂNICĂ Alexandru

    2015-12-01

    Full Text Available The study takes into account the two Romanian Eastern regions (North East and South East trying to emphasize the post-communist dynamics of the energy sector in order to draw a general perspective for the future evolution towards both energy security and a clean environment. Before 1989, the energy sector, that had to sustain not only the population needs, but also an oversized manufacturing industry, was based on big power plants usually using coal and oil and highly polluting the environment. The hydropower had a rather small share in the total energy production. This inherited system was very much resistant after the end of the centralized political system, therefore after the general industrial decline the energy sector remained the main source of air pollution in many towns and cities from Romania. Meanwhile, in the last 6-7 years, due to a favourable national political context, we assisted, especially in the analysed area, to an important emergence of renewable energy investments (mainly wind and solar energy, but also biomass or hydro-energy. Our purpose is to evaluate, from a geographical point of view, the extent and the implications of a desirable progressive shift from fossil fuels to renewable energy that could radically change the territorial relations and sustain development on the long term.

  19. The Economic Potential of Two Nuclear-Renewable Hybrid Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, Mark [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cutler, Dylan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Flores-Espino, Francisco [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stark, Greg [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jenkin, Thomas [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simpkins, Travis [National Renewable Energy Lab. (NREL), Golden, CO (United States); Macknick, Jordan [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-08-01

    Tightly coupled nuclear-renewable hybrid energy systems (N-R HESs) are an option that can generate zero-carbon, dispatchable electricity and provide zero-carbon energy for industrial processes at a lower cost than alternatives. N-R HESs are defined as systems that are managed by a single entity and link a nuclear reactor that generates heat, a thermal power cycle for heat to electricity conversion, at least one renewable energy source, and an industrial process that uses thermal and/or electrical energy. This report provides results of an analysis of two N-R HES scenarios. The first is a Texas-synthetic gasoline scenario that includes four subsystems: a nuclear reactor, thermal power cycle, wind power plant, and synthetic gasoline production technology. The second is an Arizona-desalination scenario with its four subsystems a nuclear reactor, thermal power cycle, solar photovoltaics, and a desalination plant. The analysis focuses on the economics of the N-R HESs and how they compare to other options, including configurations without all the subsystems in each N-R HES and alternatives where the energy is provided by natural gas.

  20. PROFIT MAXIMIZATION AND OPTIMAL SIZING OF RENEWABLE ENERGY SOURCES IN A HYBRID SYSTEM

    Directory of Open Access Journals (Sweden)

    YAJVENDER PAL VERMA

    2010-09-01

    Full Text Available The renewable energy sources wind, solar etc. have become very essential and important in the generation mix as a result of rising energy demand and environmental reasons. In addition tax is being imposed on high carbon emission. But the uncertainty and variability associated with renewable such as wind may result in economical andtechnical problems in the power system. In order to compensate wind intermittency, generation resources such as gas plant, pumped storage unit etc. are employed due to their lesser start up time, lower operating cost and good ramping capabilities. This paper proposes a model which investigates the combined operation of thermal, wind andpumped storage units for the profit maximization in varying wind, load, and price scenarios. The optimal size of the pumped storage unit to be used has been obtained after putting the system to different operating conditions such as varying wind power and load demand, imposing tax on carbon emission and varying ramping limits etc. The model has been applied on IEEE-30 bus test data and satisfactory results have been obtained for optimal hybrid systemoperation.

  1. Distributed Renewable Generation and Storage System Sizing Based on Smart Dispatch of Microgrids

    Directory of Open Access Journals (Sweden)

    Raji Atia

    2016-03-01

    Full Text Available This paper considers the contribution of independent owners (IOs operating within microgrids (MGs toward green power generation in deregulated energy markets. An optimization scheme is introduced for sizing distributed renewable generation (DRG and a distributed energy storage system (DESS based on a novel energy management system (EMS that accounts for demand response (DR, DESS dispatch and performance degradation, dynamic pricing environments, power distribution loss and irregular renewable generation. The proposed EMS utilizes an iterative Newton-Raphson linear programming algorithm that schedules resources in order to minimize the objective function, to deal with the complicated nonlinear nature of the problem and to enable efficient long-term assessments. The EMS is used to evaluate candidate solutions that are generated by a genetic algorithm (GA to determine the optimal combination of DRG and DESS. A case study for IEEE 34-bus distribution MG in Okinawa, Japan, is used for testing the algorithm and analyzing the potential for IO/MG investments and their strategies.

  2. Dynamic modeling of hybrid renewable energy systems for off-grid applications

    Science.gov (United States)

    Hasemeyer, Mark David

    The volatile prices of fossil fuels and their contribution to global warming have caused many people to turn to renewable energy systems. Many developing communities are forced to use these systems as they are too far from electrical distribution. As a result, numerous software models have been developed to simulate hybrid renewable energy systems. However almost, if not all, implementations are static in design. A static design limits the ability of the model to account for changes over time. Dynamic modeling can be used to fill the gaps where other modeling techniques fall short. This modeling practice allows the user to account for the effects of technological and economic factors over time. These factors can include changes in energy demand, energy production, and income level. Dynamic modeling can be particularly useful for developing communities who are off-grid and developing at rapid rates. In this study, a dynamic model was used to evaluate a real world system. A non-governmental organization interested in improving their current infrastructure was selected. Five different scenarios were analyzed and compared in order to discover which factors the model is most sensitive to. In four of the scenarios, a new energy system was purchased in order to account for the opening of a restaurant that would be used as a source of local income generation. These scenarios were then compared to a base case in which a new system was not purchased, and the restaurant was not opened. Finally, the results were used to determine which variables had the greatest impact on the various outputs of the simulation.

  3. Smart nanogrid systems for disaster mitigation employing deployable renewable energy harvesting devices

    Science.gov (United States)

    Ghasemi-Nejhad, Mehrdad N.; Menendez, Michael; Minei, Brenden; Wong, Kyle; Gabrick, Caton; Thornton, Matsu; Ghorbani, Reza

    2016-04-01

    This paper explains the development of smart nanogrid systems for disaster mitigation employing deployable renewable energy harvesting, or Deployable Disaster Devices (D3), where wind turbines and solar panels are developed in modular forms, which can be tied together depending on the needed power. The D3 packages/units can be used: (1) as a standalone unit in case of a disaster where no source of power is available, (2) for a remote location such as a farm, camp site, or desert (3) for a community that converts energy usage from fossil fuels to Renewable Energy (RE) sources, or (4) in a community system as a source of renewable energy for grid-tie or off-grid operation. In Smart D3 system, the power is generated (1) for consumer energy needs, (2) charge storage devices (such as batteries, capacitors, etc.), (3) to deliver power to the network when the smart D3 nano-grid is tied to the network and when the power generation is larger than consumption and storage recharge needs, or (4) to draw power from the network when the smart D3 nano-grid is tied to the network and when the power generation is less than consumption and storage recharge needs. The power generated by the Smart D3 systems are routed through high efficiency inverters for proper DC to DC or DC to AC for final use or grid-tie operations. The power delivery from the D3 is 220v AC, 110v AC and 12v DC provide proper power for most electrical and electronic devices worldwide. The power supply is scalable, using a modular system that connects multiple units together. This are facilitated through devices such as external Input-Output or I/O ports. The size of the system can be scaled depending on how many accessory units are connected to the I/O ports on the primary unit. The primary unit is the brain of the system allowing for smart switching and load balancing of power input and smart regulation of power output. The Smart D3 systems are protected by ruggedized weather proof casings allowing for operation

  4. The effects of LSD1 inhibition on self-renewal and differentiation of human induced pluripotent stem cells.

    Science.gov (United States)

    Yan, Hong-Jie; Zhou, Shu-Yan; Li, Yang; Zhang, Hui; Deng, Chun-Yan; Qi, Hui; Li, Fu-Rong

    2016-01-15

    Human induced pluripotent stem cells (hiPSCs) are capable of unlimited self-renewal and can generate nearly all cells in the body. Changes induced by different LSD1 activities on the regulation of hiPSC self-renewal and differentiation and the mechanism underlying such changes were determined. We used two different LSD1 inhibitors (phenelzine sulfate and tranylcypromine) and RNAi technique to inhibit LSD1 activity, and we obtained hiPSCs showing 71.3%, 53.28%, and 31.33% of the LSD1 activity in normal hiPSCs. The cells still maintained satisfactory self-renewal capacity when LSD1 activity was at 71.3%. The growth rate of hiPSCs decreased and cells differentiated when LSD1 activity was at approximately 53.28%. The hiPSCs were mainly arrested in the G0/G1 phase and simultaneously differentiated into endodermal tissue when LSD1 activity was at 31.33%. Teratoma experiments showed that the downregulation of LSD1 resulted in low teratoma volume. When LSD1 activity was below 50%, pluripotency of hiPSCs was impaired, and the teratomas mainly comprised endodermal and mesodermal tissues. This phenomenon was achieved by regulating the critical balance between histone methylation and demethylation at regulatory regions of several key pluripotent and developmental genes. PMID:26748182

  5. Opposing Effects of Tcf3 and Tcf1 Control Wnt-Stimulation of Embryonic Stem Cell Self Renewal

    OpenAIRE

    Yi, Fei; Pereira, Laura; Hoffman, Jackson A.; Shy, Brian R.; Yuen, Courtney Mingmen; Liu, David Ruchien; Merrill, Bradley J.

    2011-01-01

    The observation that Tcf3 (MGI name: Tcf7l1) bound the same genes as core stem cell transcription factors, Oct4 (MGI name:Pou5f1), Sox2 and Nanog, revealed a potentially important aspect of the poorly understood mechanism whereby Wnts stimulate self renewal of pluripotent mouse embryonic stem (ES) cells. Although the conventional view of Tcf proteins as the β-catenin-binding effectors of Wnt signaling suggested Tcf3-β-catenin mediated activation of target genes would stimulate ES cell self re...

  6. Up-regulation of the embryonic self-renewal network through reversible polyploidy in irradiated p53-mutant tumour cells

    International Nuclear Information System (INIS)

    We have previously documented that transient polyploidy is a potential cell survival strategy underlying the clonogenic re-growth of tumour cells after genotoxic treatment. In an attempt to better define this mechanism, we recently documented the key role of meiotic genes in regulating the DNA repair and return of the endopolyploid tumour cells (ETC) to diploidy through reduction divisions after irradiation. Here, we studied the role of the pluripotency and self-renewal stem cell genes NANOG, OCT4 and SOX2 in this polyploidy-dependent survival mechanism. In irradiation-resistant p53-mutated lymphoma cell-lines (Namalwa and WI-L2-NS) but not sensitive p53 wild-type counterparts (TK6), low background expression of OCT4 and NANOG was up-regulated by ionising radiation with protein accumulation evident in ETC as detected by OCT4/DNA flow cytometry and immunofluorescence (IF). IF analysis also showed that the ETC generate PML bodies that appear to concentrate OCT4, NANOG and SOX2 proteins, which extend into complex nuclear networks. These polyploid tumour cells resist apoptosis, overcome cellular senescence and undergo bi- and multi-polar divisions transmitting the up-regulated OCT4, NANOG and SOX2 self-renewal cassette to their descendents. Altogether, our observations indicate that irradiation-induced ETC up-regulate key components of germ-line cells, which potentially facilitate survival and propagation of the tumour cell population.

  7. Histone deacetylase inhibition enhances self renewal and cardioprotection by human cord blood-derived CD34 cells.

    Directory of Open Access Journals (Sweden)

    Ilaria Burba

    Full Text Available BACKGROUND: Use of peripheral blood- or bone marrow-derived progenitors for ischemic heart repair is a feasible option to induce neo-vascularization in ischemic tissues. These cells, named Endothelial Progenitors Cells (EPCs, have been extensively characterized phenotypically and functionally. The clinical efficacy of cardiac repair by EPCs cells remains, however, limited, due to cell autonomous defects as a consequence of risk factors. The devise of "enhancement" strategies has been therefore sought to improve repair ability of these cells and increase the clinical benefit. PRINCIPAL FINDINGS: Pharmacologic inhibition of histone deacetylases (HDACs is known to enhance hematopoietic stem cells engraftment by improvement of self renewal and inhibition of differentiation in the presence of mitogenic stimuli in vitro. In the present study cord blood-derived CD34(+ were pre-conditioned with the HDAC inhibitor Valproic Acid. This treatment affected stem cell growth and gene expression, and improved ischemic myocardium protection in an immunodeficient mouse model of myocardial infarction. CONCLUSIONS: Our results show that HDAC blockade leads to phenotype changes in CD34(+ cells with enhanced self renewal and cardioprotection.

  8. Cell death and renewal during prey capture and digestion in the carnivorous sponge Asbestopluma hypogea (Porifera: Poecilosclerida).

    Science.gov (United States)

    Martinand-Mari, Camille; Vacelet, Jean; Nickel, Michael; Wörheide, Gert; Mangeat, Paul; Baghdiguian, Stephen

    2012-11-15

    The sponge Asbestopluma hypogea is unusual among sponges due to its peculiar carnivorous feeding habit. During various stages of its nutrition cycle, the sponge is subjected to spectacular morphological modifications. Starved animals are characterized by many elongated filaments, which are crucial for the capture of prey. After capture, and during the digestion process, these filaments actively regress before being regenerated during a subsequent period of starvation. Here, we demonstrate that these morphological events rely on a highly dynamic cellular turnover, implying a coordinated sequence of programmed cell death (apoptosis and autophagy), cell proliferation and cell migration. A candidate niche for cell renewal by stem cell proliferation and differentiation was identified at the base of the sponge peduncle, characterized by higher levels of BrdU/EdU incorporation. Therefore, BrdU/EdU-positive cells of the peduncle base are candidate motile cells responsible for the regeneration of the prey-capturing main sponge body, i.e. the dynamic filaments. Altogether, our results demonstrate that dynamics of cell renewal in sponge appear to be regulated by cellular mechanisms as multiple and complex as those already identified in bilaterian metazoans. PMID:22899530

  9. Assesment of Emerging Renewable Energy-based Cogeneration Systems for nZEB Residential Buildings

    DEFF Research Database (Denmark)

    Carmo, Carolina; Dumont, Olivier; Nielsen, Mads Pagh;

    2016-01-01

    entail production of electricity and usable thermal energy (heat and/or cooling) to cover the energy demands of residential buildings, high energy efficiency levels and proximity of the energy source to the building. The concept of cogeneration is not new but the interest in small scale cogeneration...... technologies based on renewable energy sources has increased tremendously in the last decade. A significant amount of experimental and modelling research has recently been presented on emerging technologies. In this paper, four main technologies are assessed: Fuel Cells (FC), Photovoltaic thermal (PV/T), solar...... thermal reversible heat pump /organic Rankine cycle (HP/ORC) and cogeneration solar Thermoelectric generators (TEG). This paper aims to give an overview of the state-of-the-art developments, discuss the fundamental and technical challenges facing commercial adoption and prospects of these technologies for...

  10. Optimal operation of conventional power plants in power system with integrated renewable energy sources

    International Nuclear Information System (INIS)

    Highlights: ► Approach for solving the generation scheduling problem of a complex system. ► WPPs integration into the system in order to minimize the total system fuel costs. ► Application on specific system consisted of TPPs, HPPs, PSHPP and WPP. - Abstract: This paper presents an approach for solving the generation scheduling problem of a complex system consisted of conventional and renewable energy sources (RES). Wind power plants are integrated into the system in order to minimize the total thermal unit fuel costs. The gained results for wind farm power production are used as input in the system to determine the optimal amounts of generated power for the thermal generating units and hydro generating units over the study period. The optimization problem consists of minimizing the total production costs, respecting power balance equations for each time interval and all operational system constraints. The proposed approach is applied on a specific system consisted of thermal power plants (TPPs), storage hydro power plants (HPPs), pumped-storage hydro power plant (PSHPP) and wind power plant (WPP). The benefits of energy production from WPP, in terms of reducing the production costs of conventional thermal power plants are also investigated. In the proposed paper two cases are analyzed. In the two analyzed cases power unit’s generation, thermal unit’s fuel costs and stream flows of hydro units are calculated over the study period.

  11. Performance Analysis of a Hybrid Generation System of Wind Turbines, Photovoltaic Modules, and a Fuel Cell

    Directory of Open Access Journals (Sweden)

    Bartosz Ceran

    2015-06-01

    Full Text Available This paper presents the results of energy analysis of a generation system consisting of wind turbines, photovoltaic modules, a fuel cell with a polymer membrane, and an electrolyser. The analysis was carried out for three configurations of generating devices’ connections with consumer: I – wind turbines and photovoltaic modules supply electrolyser, II – paralel co-operation of fuel cell with renewables, III – renewables supply electrolyser, with the option of direct supply of the consumer.

  12. The Cost-Optimal Distribution of Wind and Solar Generation Facilities in a Simplified Highly Renewable European Power System

    Science.gov (United States)

    Kies, Alexander; von Bremen, Lüder; Schyska, Bruno; Chattopadhyay, Kabitri; Lorenz, Elke; Heinemann, Detlev

    2016-04-01

    The transition of the European power system from fossil generation towards renewable sources is driven by different reasons like decarbonisation and sustainability. Renewable power sources like wind and solar have, due to their weather dependency, fluctuating feed-in profiles, which make their system integration a difficult task. To overcome this issue, several solutions have been investigated in the past like the optimal mix of wind and PV [1], the extension of the transmission grid or storages [2]. In this work, the optimal distribution of wind turbines and solar modules in Europe is investigated. For this purpose, feed-in data with an hourly temporal resolution and a spatial resolution of 7 km covering Europe for the renewable sources wind, photovoltaics and hydro was used. Together with historical load data and a transmission model , a simplified pan-European power power system was simulated. Under cost assumptions of [3] the levelized cost of electricity (LCOE) for this simplified system consisting of generation, consumption, transmission and backup units is calculated. With respect to the LCOE, the optimal distribution of generation facilities in Europe is derived. It is shown, that by optimal placement of renewable generation facilities the LCOE can be reduced by more than 10% compared to a meta study scenario [4] and a self-sufficient scenario (every country produces on average as much from renewable sources as it consumes). This is mainly caused by a shift of generation facilities towards highly suitable locations, reduced backup and increased transmission need. The results of the optimization will be shown and implications for the extension of renewable shares in the European power mix will be discussed. The work is part of the RESTORE 2050 project (Wuppertal Institute, Next Energy, University of Oldenburg), that is financed by the Federal Ministry of Education and Research (BMBF, Fkz. 03SFF0439A). [1] Kies, A. et al.: Kies, Alexander, et al

  13. Simulation of long term renewable energy feed-in for European power system studies

    Science.gov (United States)

    Kies, Alexander; Nag, Kabitri; von Bremen, Lueder; Lorenz, Elke; Heinemann, Detlev; Späth, Stephan

    2014-05-01

    Renewable energies already play a remarkable role in Europe as of today. It is expected that wind and solar amongst other renewables will contribute strongly to the future European energy generation. However, wind and solar generation facilities have due to the weather dependent nature of their resources highly fluctuating feed-in profiles. To overcome the mismatch between energy demand and generation it is important to study and understand the generation patterns and balancing potentials. The goal of the current work is to investigate how the feed-in time series from different renewable sources like on- and offshore wind, photovoltaic, solar thermal, wave, hydro, geothermal and biomass power and combination of them look like in an European power supply system . The work is part of the RESTORE 2050 project (BMU) that investigates the requirements for cross-country grid extensions, usage of storage technologies and capacities, the development of new balancing technologies and the conceptual design of the future energy market which is suitable for high generation percentages of solar and wind. High temporally and spatially resolved long term weather data from COSMO-EU, MERRA and Meteosat (MFG/MSG) satellite data has been used to simulate feed-in from several types of renewable energy sources on a 7 x 7 km grid covering Europe. For wind speeds MERRA reanalysis data has been statistically downscaled to account for orography. Generation was aggregated on the country level and production patterns and their variations in time of different resources were investigated for the years ranging from 2002 to 2012. In a first step the quality of the simulated feed in time series has been investigated by comparison to real observations of wind power and PV generation. Furthermore, some sensitivity studies with respect to underlying assumptions like spatial distribution of wind and PV capacities, the chosen hub-height and wind power curve have been done and will be presented. While

  14. Model documentation renewable fuels module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1997 Annual Energy Outlook forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs. and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. This documentation report serves three purposes. First, it is a reference document for model analysts, model users, and the public interested in the construction and application of the RFM. Second, it meets the legal requirement of the Energy Information Administration (EIA) to provide adequate documentation in support of its models. Finally, such documentation facilitates continuity in EIA model development by providing information sufficient to perform model enhancements and data updates as part of EIA`s ongoing mission to provide analytical and forecasting information systems.

  15. Model documentation renewable fuels module of the National Energy Modeling System

    International Nuclear Information System (INIS)

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1997 Annual Energy Outlook forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs. and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. This documentation report serves three purposes. First, it is a reference document for model analysts, model users, and the public interested in the construction and application of the RFM. Second, it meets the legal requirement of the Energy Information Administration (EIA) to provide adequate documentation in support of its models. Finally, such documentation facilitates continuity in EIA model development by providing information sufficient to perform model enhancements and data updates as part of EIA's ongoing mission to provide analytical and forecasting information systems

  16. Combined heat and power (cogeneration) plant based on renewable energy sources and electrochemical hydrogen systems

    Science.gov (United States)

    Grigor'ev, S. A.; Grigor'ev, A. S.; Kuleshov, N. V.; Fateev, V. N.; Kuleshov, V. N.

    2015-02-01

    The layout of a combined heat and power (cogeneration) plant based on renewable energy sources (RESs) and hydrogen electrochemical systems for the accumulation of energy via the direct and inverse conversion of the electrical energy from RESs into the chemical energy of hydrogen with the storage of the latter is described. Some efficient technical solutions on the use of electrochemical hydrogen systems in power engineering for the storage of energy with a cyclic energy conversion efficiency of more than 40% are proposed. It is shown that the storage of energy in the form of hydrogen is environmentally safe and considerably surpasses traditional accumulator batteries by its capacitance characteristics, being especially topical in the prolonged absence of energy supply from RESs, e.g., under the conditions of polar night and breathless weather. To provide the required heat consumption of an object during the peak period, it is proposed to burn some hydrogen in a boiler house.

  17. Renewable build-up pathways for the US: Generation costs are not system costs

    CERN Document Server

    Becker, Sarah; Andresen, Gorm B; Jacobson, Mark Z; Schramm, Stefan; Greiner, Martin

    2014-01-01

    The transition to a future electricity system based primarily on wind and solar PV is examined for all regions in the contiguous US. We present optimized pathways for the build-up of wind and solar power for least backup energy needs as well as for least cost obtained with a simplified, lightweight model based on long-term high resolution weather-determined generation data. In the absence of storage, the pathway which achieves the best match of generation and load, thus resulting in the least backup energy requirements, generally favors a combination of both technologies, with a wind/solar PV energy mix of about 80/20 in a fully renewable scenario. The least cost development is seen to start with 100% of the technology with the lowest average generation costs first, but with increasing renewable installations, economically unfavorable excess generation pushes it toward the minimal backup pathway. Surplus generation and the entailed costs can be reduced significantly by combining wind and solar power, and/or a...

  18. Model documentation, Renewable Fuels Module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the Annual Energy Outlook 1998 (AEO98) forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. For AEO98, the RFM was modified in three principal ways, introducing capital cost elasticities of supply for new renewable energy technologies, modifying biomass supply curves, and revising assumptions for use of landfill gas from municipal solid waste (MSW). In addition, the RFM was modified in general to accommodate projections beyond 2015 through 2020. Two supply elasticities were introduced, the first reflecting short-term (annual) cost increases from manufacturing, siting, and installation bottlenecks incurred under conditions of rapid growth, and the second reflecting longer term natural resource, transmission and distribution upgrade, and market limitations increasing costs as more and more of the overall resource is used. Biomass supply curves were also modified, basing forest products supplies on production rather than on inventory, and expanding energy crop estimates to include states west of the Mississippi River using information developed by the Oak Ridge National Laboratory. Finally, for MSW, several assumptions for the use of landfill gas were revised and extended.

  19. Hybrid Geo-Energy Systems for Energy Storage and Dispatchable Renewable and Low-Carbon Electricity

    Science.gov (United States)

    Buscheck, Thomas; Bielicki, Jeffrey; Ogland-Hand, Jonathan; Hao, Yue; Sun, Yunwei; Randolph, Jimmy; Saar, Martin

    2015-04-01

    Three primary challenges for energy systems are to (1) reduce the amount of carbon dioxide (CO2) being emitted to the atmosphere, (2) increase the penetration of renewable energy technologies, and (3) reduce the water intensity of energy production. Integrating variable renewable energy sources (wind, sunlight) into electric grids requires advances in energy storage approaches, which are currently expensive, and tend to have limited capacity and/or geographic deployment potential. Our approach uses CO2, that would otherwise be emitted to the atmosphere, to generate electricity from geothermal resources, to store excess energy from variable (wind, solar photovoltaic) and thermal (nuclear, fossil, concentrated solar power) sources, and to thus enable increased penetration of renewable energy technologies. We take advantage of the enormous fluid and thermal storage capacity of the subsurface to harvest, store, and dispatch energy. Our approach uses permeable geologic formations that are vertically bounded by impermeable layers to constrain pressure and the migration of buoyant CO2 and heated brine. Supercritical CO2 captured from fossil power plants is injected into these formations as a cushion gas to store pressure (bulk energy), provide an heat efficient extraction fluid for efficient power conversion in Brayton Cycle turbines, and generate artesian flow of brine -- which can be used to cool power plants and/or pre-heated (thermal storage) prior to re-injection. Concentric rings of injection and production wells create a hydraulic divide to store pressure, CO2, and thermal energy. The system is pressurized and/or heated when power supply exceeds demand and depressurized when demand exceeds supply. Time-shifting the parasitic loads from pressurizing and injecting brine and CO2 provides bulk energy storage over days to months, whereas time-shifting thermal-energy supply provides dispatchable power and addresses seasonal mismatches between supply and demand. These

  20. Changing the Energy System towards Renewable Energy Self-Sufficiency—Towards a multi-perspective and Interdisciplinary Framework

    Directory of Open Access Journals (Sweden)

    Chantal Ruppert-Winkel

    2014-05-01

    Full Text Available The transformation of the present energy system into a sustainable one is discussed worldwide. This is also mirrored in a vivid debate in the scientific literature [1–3]. Self-sufficiency attained with the help of electricity, heat, and fuel from renewable energy (RE in combination with energy saving is seen as one way to establish a sustainable energy system, e.g., [4,5]. Many communities and regions in different countries are facing the challenge of such a transformation of their energy system, and have taken up the objective of achieving energy self-sufficiency through the use of renewables [4,6–8]. [...