Dissertations / Theses: 'Green hydrogen energy systems'

1

Hendriks, Kjel. "Disruptive Innovation in Green Energy Sectors: An Entrepreneurial Perspective." Thesis, Jönköping University, IHH, Företagsekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-52853.

Full text

Abstract:

Background: Green hydrogen energy systems can address environmental and societal concerns within the energy sector. Therefore, increased attentions from both public and private stakeholders has led to the general perception that hydrogen systems can serve as a disruptive innovation. Given that disruption innovation theory has seen increased entrepreneurial involvement over recent years, the study focuses on assessing the role of green entrepreneurs within the implementation of hydrogen systems through cross-collaborative efforts and disruptive innovation drivers. Purpose: The development of a theoretical matrix that interconnects disruptive innovation, entrepreneurial involvement, and cross-collaborative initiatives to establish entrepreneurial positioning roles within the energy market. Method: The epistemology chosen was interpretivist, and its ontology subjectivism. The research followed an inductive approach. The research was qualitatively conducted and adopted a case study approach. The data was collected through semi-structured interviews, and followed a theoretical sampling approach. Conclusion: The study proposes a theoretical matrix that extended disruptive innovation theory to green entrepreneurship and concluded that high levels of cross-collaboration, and a high innovation impact, serve as key drivers for green entrepreneurial implementations of disruptive energy. Results highlight the need for entrepreneurial involvement across all stages of market implementations.

APA, Harvard, Vancouver, ISO, and other styles

2

Gazey, Ross Neville. "Sizing hybrid green hydrogen energy generation and storage systems (HGHES) to enable an increase in renewable penetration for stabilising the grid." Thesis, Robert Gordon University, 2014. http://hdl.handle.net/10059/947.

Full text

Abstract:

A problem that has become apparently growing in the deployment of renewable energy systems is the power grids inability to accept the forecasted growth in renewable energy generation integration. To support forecasted growth in renewable generation integration, it is now recognised that Energy Storage Technologies (EST) must be utilised. Recent advances in Hydrogen Energy Storage Technologies (HEST) have unlocked their potential for use with constrained renewable generation. HEST combines Hydrogen production, storage and end use technologies with renewable generation in either a directly connected configuration, or indirectly via existing power networks. A levelised cost (LC) model has been developed within this thesis to identify the financial competitiveness of the different HEST application scenarios when used with grid constrained renewable energy. Five HEST scenarios have been investigated to demonstrate the most financially competitive configuration and the benefit that the by-product oxygen from renewable electrolysis can have on financial competitiveness. Furthermore, to address the lack in commercial software tools available to size an energy system incorporating HEST with limited data, a deterministic modelling approach has been developed to enable the initial automatic sizing of a hybrid renewable hydrogen energy system (HRHES) for a specified consumer demand. Within this approach, a worst-case scenario from the financial competitiveness analysis has been used to demonstrate that initial sizing of a HRHES can be achieved with only two input data, namely – the available renewable resource and the load profile. The effect of the electrolyser thermal transients at start-up on the overall quantity of hydrogen produced (and accordingly the energy stored), when operated in conjunction with an intermittent renewable generation source, has also been modelled. Finally, a mass-transfer simulation model has been developed to investigate the suitability of constrained renewable generation in creating hydrogen for a hydrogen refuelling station.

APA, Harvard, Vancouver, ISO, and other styles

3

Thekkenthiruthummal, Kunjumon Razif, and Baby Rinto Cheruvil. "Feasibility Study of Green Hydrogen PowerGeneration in Kavaratti Island, India." Thesis, Högskolan i Halmstad, Akademin för företagande, innovation och hållbarhet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-44617.

Full text

Abstract:

Controlling greenhouse gas emissions is essential by the introduction of renewable energysources. The island Lakshadweep in India has been dependent on non-renewable generationof electricity over the years. To make them self-sufficient in the energy sector, theintroduction of green hydrogen from wind and solar sources and its storage for sustainablefuture is a great initiative. The factors such as renewable sources, electrolyzer technology,fuel cells included in hydrogen production are optimized for this project in a cost-effectivemanner over the existing diesel power generation. The cost comparison of this greenhydrogen system with cost of diesel for next 20 years clearly illustrated the importance ofrenewable energy sources for a sustainable future.

APA, Harvard, Vancouver, ISO, and other styles

4

Gammon, Rupert. "The integration of hydrogen energy storage with renewable energy systems." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7847.

Full text

Abstract:

This thesis concerns the design, implementation and operation of a hydrogen energy storage facility that has been added to an existing renewable energy system at West Beacon Farm, Leicestershire, UK. The hydrogen system consists of an electrolyser, a pressurised gas store and fuel cells. At times of surplus electrical supply, the electrolyser converts electrical energy into chemical energy in the form of hydrogen. This hydrogen is stored until there is a shortage of electrical energy to power the loads on the system, at which point it is reconverted back to electricity by the process of reverse-electrolysis that takes place within a fuel cell. The renewable energy sources, supplying electrical power to domestic and office loads at the site, are photovoltaic, wind and micro-hydroelectric. This work is being carried out through a project, conceived and overseen by the author, known as the Hydrogen and Renewables Integration (HARI) project. The purpose of this study is to demonstrate and gain experience in the integration of hydrogen energy storage with renewable energy systems and, most importantly, to develop software models that could be used for the design of future systems of this type in a range of applications. Effective models have been created and verified against the real-world operation of the system. These models have been largely completed, although some minor details remain unfinished as the are dependant upon studies linked to this one which are yet to be concluded. Subject to some fine tuning that this would entail, then, the models can be used to design a stand-alone, integrated hydrogen and renewable energy system, where only the load profile and weather conditions of a site are known. Significant practical experience has been gained through the design, installation and two years' of operation of the system. Many important insights have been obtained in relation to the integration of the system and the design and operation of its components.

APA, Harvard, Vancouver, ISO, and other styles

5

Korpås, Magnus. "Distributed Energy Systems with Wind Power and Energy Storage." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-132.

Full text

Abstract:

The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy storage systems should be designed and operated in order to increase the penetration and value of wind power in the power system. Optimization models and sequential and probabilistic simulation models have been developed for this purpose.Chapter 3 presents a sequential simulation model of a general windhydrogen energy system. Electrolytic hydrogen is used either as a fuel for transportation or for power generation in a stationary fuel cell. The model is useful for evaluating how hydrogen storage can increase the penetration of wind power in areas with limited or no transmission capacity to the main grid. The simulation model is combined with a cost model in order to study how component sizing and choice of operation strategy influence the performance and economics of the wind-hydrogen system. If the stored hydrogen is not used as a separate product, but merely as electrical energy storage, it should be evaluated against other and more energy efficient storage options such as pumped hydro and redox flow cells. A probabilistic model of a grid-connected wind power plant with a general energy storage unit is presented in chapter 4. The energy storage unit is applied for smoothing wind power fluctuations by providing a firm power output to the grid over a specific period. The method described in the chapter is based on the statistical properties of the wind speed and a general representation of the wind energy conversion system and the energy storage unit. This method allows us to compare different storage solutions.In chapter 5, energy storage is evaluated as an alternative for increasing the value of wind power in a market-based power system. A method for optimal short-term scheduling of wind power with energy storage has been developed. The basic model employs a dynamic programming algorithm for the scheduling problem. Moreover, different variants of the scheduling problem based on linear programming are presented. During on-line operation, the energy storage is operated to minimize the deviation between the generation schedule and the actual power output of the wind-storage system. It is shown how stochastic dynamic programming can be applied for the on-line operation problem by explicitly taking into account wind forecast uncertainty. The model presented in chapter 6 extends and improves the linear programming model described in chapter 5. An operation strategy based on model predictive control is developed for effective management of uncertainties. The method is applied in a simulation model of a wind-hydrogen system that supplies the local demand for electricity and hydrogen. Utilization of fuel cell heat and electrolytic oxygen as by-products is also considered. Computer simulations show that the developed operation method is beneficial for grid-connected as well as for isolated systems. For isolated systems, the method makes it possible to minimize the usage of backup power and to ensure a secure supply of hydrogen fuel. For grid-connected wind-hydrogen systems, the method could be applied for maximizing the profit from operating in an electricity market.Comprehensive simulation studies of different example systems have been carried out to obtain knowledge about the benefits and limitations of using energy storage in conjunction with wind power. In order to exploit the opportunities for energy storage in electricity markets, it is crucial that the electrical efficiency of the storage is as high as possible. Energy storage combined with wind power prediction tools makes it possible to take advantage of varying electricity prices as well as reduce imbalance costs. Simulation results show that the imbalance costs of wind power and the electricity price variations must be relatively high to justify the installation of a costly energy storage system. Energy storage is beneficial for wind power integration in power systems with high-cost regulating units, as well as in areas with weak grid connection.Hydrogen can become an economically viable energy carrier and storage medium for wind energy if hydrogen is introduced into the transportation sector. It is emphasized that seasonal wind speed variations lead to high storage costs if compressed hydrogen tanks are used for long-term storage. Simulation results indicate that reductions in hydrogen storage costs are more important than obtaining low-cost and high-efficient fuel cells and electrolyzers. Furthermore, it will be important to make use of the flexibility that the hydrogen alternative offers regarding sizing, operation and possibly the utilization of oxygen and heat as by-products.The main scientific contributions from this thesis are the development of- a simulation model for estimating the cost and energy efficiency of wind-hydrogen systems,- a probabilistic model for predicting the performance of a gridconnected wind power plant with energy storage,- optimization models for increasing the value of wind power in electricity markets by the use of hydrogen storage and other energy storage solutions and the system knowledge about wind energy and energy storage that has been obtained by the use of these models. Paper 1 is reprinted with kind permission of ACTA Press. Paper 2 is reprinted with kind permission of Elsevier/ Science Direct. http://www.elsevier.com, http://www.sciencedirect.com Paper 3 is reprinted with kind permission of IEEE.

APA, Harvard, Vancouver, ISO, and other styles

6

Janon, Akraphon, and s2113730@student rmit edu au. "Wind-hydrogen energy systems for remote area power supply." RMIT University. Aerospace, Mechanical & Manufacturing Engineering, 2010. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20100329.094605.

Full text

Abstract:

Wind-hydrogen systems for remote area power supply are an early niche application of sustainable hydrogen energy. Optimal direct coupling between a wind turbine and an electrolyser stack is essential for maximum electrical energy transfer and hydrogen production. In addition, system costs need to be minimised if wind-hydrogen systems are to become competitive. This paper investigates achieving near maximum power transfer between a fixed pitched variable-speed wind turbine and a Proton Exchange Membrane (PEM) electrolyser without the need for intervening voltage converters and maximum power point tracking electronics. The approach investigated involves direct coupling of the wind turbine with suitably configured generator coils to an optimal series-parallel configuration of PEM electrolyser cells so that the I-V characteristics of both the wind turbine and electrolyser stack are closely matched for maximum power transfer. A procedure for finding these optimal con figurations and hence maximising hydrogen production from the system is described. For the case of an Air 403 400 W wind turbine located at a typical coastal site in south-eastern Australia and directly coupled to an optimally configured 400 W stack of PEM electrolysers, it is estimated that up to 95% of the maximum achievable energy can be transferred to the electrolyser over an annual period. The results of an extended experiment to test this theoretical prediction for an actual Air 403 wind turbine are reported. The implications of optimal coupling between a PEM electrolyser and an aerogenerator for the performance and overall economics of wind-energy hydrogen systems for RAPS applications are discussed.

APA, Harvard, Vancouver, ISO, and other styles

7

Monaghan, Rory F. D. (Rory Francis Desmond). "Hydrogen storage of energy for small power supply systems." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32361.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. Includes bibliographical references (p. 91-92). Power supply systems for cell phone base stations using hydrogen energy storage, fuel cells or hydrogen-burning generators, and a backup generator could offer an improvement over current power supply systems. Two categories of hydrogen-based power systems were analyzed: Wind-hydrogen systems and peak-shaving hydrogen systems. Modeling of base station requirements and alternative power supply system performance was carried out using MATLAB. Final results for potential alternative systems were compared to those for the current power systems. In the case of the wind- hydrogen systems, results were also compared to those of a wind-battery system. Overall feasibility was judged primarily on the net present cost of the power supply systems. Other considerations included conformity to present regulations. Sensitivity analysis of the wind-hydrogen model was carried out to identify the controlling variables. Numerous parameters were varied over realistic ranges. Important parameters were found to include wind resource, electrolyzer size, distance from electricity grid, price of diesel fuel, and electrolyzer and fuel cell cost. The model verified cell phone industry figures regarding the geographical conditions favorable to diesel genset use. Final results for wind-hydrogen systems suggest that for today's electrolyzer and fuel cell costs, wind-battery-diesel systems are the most suitable power system more than 8km from the existing electricity grid, with an annual average wind speed of 7m/s or more, and where diesel costs more than $2.20/gallon. (cont.) Thinking to the future, with 20% reduced electrolyzer and fuel cell costs, a wind-fuel cell-diesel system with a 15kW electrolyzer is the most suitable system at locations greater than 8km from the existing electricity grid with an annual average wind speed of 7rn/s or more and total diesel costs greater than $2/gallon. Within 8km the grid, in all cases, grid connection is most suitable. Outside this range, with diesel prices below $2/gallon, a genset only system is most suitable in most cases. Analysis of the peak-shaving hydrogen system suggests that it is not suitable for deployment under any realistic circumstances. Replenishment of hydrogen stores has a substantial power requirement. by Rory F.D. Monaghan. S.M.

APA, Harvard, Vancouver, ISO, and other styles

8

Liu, Jiashang. "Resource Allocation and Energy Management in Green Network Systems." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587577356321898.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Chidziva, Stanford. "Green hydrogen production for fuel cell applications and consumption in SAIAMC research facility." University of Western Cape, 2020. http://hdl.handle.net/11394/7859.

Full text

Abstract:

Philosophiae Doctor - PhD Today fossil fuels such as oil, coal and natural gas are providing for our ever growing energy needs. As the world’s fossil fuel reserves fast become depleted, it is vital that alternative and cleaner fuels are found. Renewable energy sources are the way of the future energy needs. A solution to the looming energy crisis can be found in the energy carrier hydrogen. Hydrogen can be produced by a number of production technologies. One hydrogen production method explored in this study is electrolysis of water.

APA, Harvard, Vancouver, ISO, and other styles

10

Björkman, Katarina. "Hydrogen gas in Sweden : Is hydrogen gas a viable energy carrier in Sweden?" Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-49015.

Full text

Abstract:

Detta arbete innefattar att undersöka hur vätgas kan användas i Sverige, dels för energilagring men även som bränsle för fordon. Den ökande användningen av varierande förnyelsebara energikällor i den svenska energimixen innebär problem med stabilitet i kraftnätet, något som energilagring kan vara en lösning på. Samtidigt finns mål att fasa ut fossila energikällor, exempelvis diesel och bensin, något som transportsektorn är mycket beroende av. Enligt intervjuerna så är ett av de stora hindren för att implementera vätgas i Sverige att det saknas standarder och regelverk. Likaså framkommer det att de intervjuobjektens projekt inom vätgas i nuläget inte är pengamässigt lönsamma. I beräkningarna framkom det att varken det nuvarande fallet eller målfallet leder till lönsamma investeringar. Den sektor som är närmast lönsamhet är transportsektorn som kräver antingen en minskning på 90 % av komponenternas kostnad eller en 10-faldig ökning av priset på fossila bränslen. Slutsatserna dragna i denna studie är att det finns användningsområden för vätgas inom flera områden, bränsle, energilagring och inom industrin, utöver den användningen inom industrin som finns idag. För att ha en hållbar produktion av vätgas bör denna vara med elektrolys som baseras på emissionsfri elektricitet, exempelvis från solceller. De ekonomiska målen, i studien kallat target case, är inte tillräckliga utan ytterligare kostnadsminskningar kommer att behövas. There is a rising demand for energy and at the same time, fossil fuels need to be phased out due to global warming. This means that the energy needs to come from renewable energy resources, for instance photovoltaics. One issue with such energy sources is that they may have variating production which can induce issues with stability in the electrical grid. This study aims to investigate hydrogen in Sweden as energy storage and vehicle fuel. Methods used are literature review, interviews and calculations. According to the interviews are one of the main issues with implementing hydrogen the lack of standards. Today it is the local fire department who approves of hydrogen system which induces irregularities in the handling. It is also said that none of the projects in the interviews is profitable moneywise, something that also can be seen in the calculations. In order to reach break-even some serious changes with regarding costs of components or the alternative, for instance, fossil fuel and electricity. The application closest to break even is transportation which demands a 90 % decrease in component price or a 10-fold increase in fossil fuel price. In conclusion, there are future applications for hydrogen as energy storage, vehicle fuel and in industry, apart from the current industry applications. The most sustainable way to produce hydrogen is via electrolysis with emission-free electricity. In order for hydrogen to become economically viable, the target case is not enough but even greater cost reductions are needed.

APA, Harvard, Vancouver, ISO, and other styles

11

Rossi, Gianmarco. "modeling of proton exchange membrane water electrolyzer for green hydrogen production from solar energy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

Find full text

Abstract:

Hydrogen is considered one of the means by which to store energy coming from renewable and intermittent power sources. With the growing capacity of renewable energy sources, a storage system is required to not waste energy. PEM electrolysis provides a sustainable solution for the production of hydrogen and is well suited to couple with energy sources such as solar and wind. This work reports the development of simulation software to estimate the performance of a proton exchange membrane electrolyzer working at atmospheric or low pressure conditions connected to a solar energy source. The electrolyzer is defined from a validated reference semi-empirical model, which allows for simulating the electrochemical, thermal and H2 output flow behaviours with enough precision for engineering applications. An algorithm for a fitting procedure to characterize commercial products, and functions for power modulation have been implemented. A series of simulations have been carried on, starting from real photovoltaic data of input power, and the output values have been discussed, with particular attention to output flow rate, thermal behaviour and the cooling demand in order to preserve the operation of the electrolyzer.

APA, Harvard, Vancouver, ISO, and other styles

12

Puranik, Sachin V. "Control of Fuel Cell Based Green Energy Systems for Distributed Generation Applications." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253476960.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Keville, Kurt (Kurt Lawrence). "Green HPC : a system design approach to energy-efficient datacenters." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67557.

Full text

Abstract:

Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2011. Cataloged from PDF version of thesis. Includes bibliographical references (p. 63-65). Green HPC is the new standard for High Performance Computing (HPC). This has now become the primary interest among HPC researchers because of a renewed emphasis on Total Cost of Ownership (TCO) and the pursuit of higher performance. Quite simply, the cost of operating modern HPC equipment can rapidly outstrip the cost of acquisition. This phenomenon is recent and can be traced to the inadequacies in modern CPU and Datacenter systems design. This thesis analyzes the problem in its entirety and describe best practice fixes to solve the problems of energy-inefficient HPC. by Kurt Keville. S.M.in Engineering and Management

APA, Harvard, Vancouver, ISO, and other styles

14

Jagtap, Rohan Surendra, and Smruti Smarak Mohanty. "Sustainable Manufacturing: Green Factory : A case study of a tool manufacturing company." Thesis, Linköpings universitet, Energisystem, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168688.

Full text

Abstract:

Efficient use of resources and utility is the key to reduce the price of the commodities produced in any industry. This in turn would lead to reduced price of the commodity which is the key to success. Sustainability involves integration of all the three dimensions: environmental, economic and social. Sustainable manufacturing involves the use of sustainable processes and systems to produce better sustainable products. These products will be more attractive, and the industry will know more about the climate impact from their production. Manufacturing companies use a considerable amount of energy in their production processes. One important area to understand the sustainability level at these types of industries is to study this energy use. The present work studies energy use in a large-scale tool manufacturing company in Sweden. Value Stream Mapping method is implemented for the purpose of mapping the energy use in the different operations. To complement this, an energy audit has been conducted, which is a method that include a study and analysis of a facility, indicating possible areas of improvements by reducing energy use and saving energy costs. This presents an opportunity for the company to implement energy efficiency measures, thus generating positive impacts through budget savings. Less energy use is also good for the environment resulting in less greenhouse gas emissions level. This also helps in long-term strategic planning and initiatives to assess the required needs and stabilize energy use for the long run. Social sustainability completes the triad along with environmental and economic sustainability. In this study, the social sustainability is reflected with the company’s relationship with its working professionals by conducting a survey. The sustainable manufacturing potential found in the case study indicates that significant progress can be made in the three sustainability dimensions. Although, the scope of the thesis is limited to a tool manufacturing company, several of the findings could be implemented in other tool companies as well as industries belonging to other sectors. The thesis is a joint report between Linköping and Uppsala University. My thesis teammate has published it before at UU Diva Portal. The URL is: https://uu.diva-portal.org/smash/record.jsf?dswid=8179&pid=diva2%3A1449223&c=1&searchType=SIMPLE&language=en&query=sustainable+manufacturing&af=%5B%22dateIssued%3A2020%22%5D&aq=%5B%5B%5D%5D&aq2=%5B%5B%5D%5D&aqe=%5B%5D&noOfRows=50&sortOrder=author_sort_asc&sortOrder2=title_sort_asc&onlyFullText=false&sf=undergraduate Green Factory project, AB Sandvik Coromant

APA, Harvard, Vancouver, ISO, and other styles

15

Bimbo, Nuno Maria Marques dos Santos. "Modelling and analysis of hydrogen storage in nanostructured solids for sustainable energy systems." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577745.

Full text

Abstract:

As societies depart from current economic models which are built around affordable and easily accessible fossil fuels to energy systems increasingly based on the use of renewable energies, the need grows for a wide-scale clean and sustainable energy vector. Hydrogen fulfils most of the needed equirements, but implementation and large scale penetration, especially for mobile applications, is precluded by technical issues. Among these, arguably the most complex is how to safely, economically and efficiently store hydrogen. Storage in a porous material offers some attractive features, which include fast kinetics, reversibility and moderate energy penalties. A new methodology to analyse hydrogen adsorption isotherms in microporous materials is presented in this thesis. The methodology is applied to hydrogen adsorption in different classes of high-surface area materials but could in principle be used for any supercritical fluid adsorbed onto a microporous material. To illustrate the application of the methodology, high-pressure hydrogen adsorption isotherms of four different materials were analysed, metal-organic frameworks MIL-101 and NOTT-101 and carbons AX-21 and TE7. The analysis extracts important information on the adsorptive capacities of the materials and compares them with conventional storage methods, which include compression, liquefaction and cryogenic compression. The methodology also aids in the calculation of the thermodynamics of adsorption, providing a more accurate calculation method than currently reported techniques, demonstrated with the calculation of the differential isosteric enthalpies for metal-organic framework NOTT-101. NMR and INS are used in a novel way at the same operating conditions of sorption experiments to validate the findings of the analysis. Both methods provide a qualitative validation for the analysis. Remarkably, the INS reveals that the adsorbed hydrogen in TE7 is in a solid-like state. GCMC simulations were also used to compare with the application and findings of the methodology, using silicalite-1 as a test material.

APA, Harvard, Vancouver, ISO, and other styles

16

Tlili, Olfa. "Hydrogen systems : what contribution to the energy system? Findings from multiple modelling approaches." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC083/document.

Full text

Abstract:

L'hydrogène… Cet élément simple et très abondant pourrait être un contributeur clé à la transition énergétique, mais dans quelles conditions technico-économiques et politiques ? Cette thèse propose une contribution à l'évaluation de la faisabilité de pénétration de l'hydrogène dans le système énergétique, en mettant en oeuvre différents modèles qui permettent des éclairages complémentaires. Elle se concentre sur l’hydrogène bas carbone, obtenu par électrolyse de l’eau.Notre analyse multirégionale qui porte sur le contexte énergétique européen, américain, chinois et japonais (régions qui présentent des défis énergétiques contrastés) montre que les politiques énergétiques actuelles ne facilitent qu’une faible pénétration de l'hydrogène dans le système énergétique, lui permettant de réaliser environ 3% de l’effort à fournir par les quatre régions afin de limiter l’augmentation de la température à 2°C par rapport aux niveaux préindustriels. Nous soulignons dans cette thèse que l’injection d’hydrogène dans les réseaux de gaz naturel qui permet dans une certaine mesure d’éviter des fuites de méthane à fort pouvoir de réchauffement, pourrait jouer un rôle significatif dans la réalisation des objectifs de réduction des émissions de gaz à effet de serre.L'analyse des marchés de l'hydrogène a été menée en deux étapes. Tout d'abord, chaque marché (industriel ou énergétique) a été abordé individuellement afin d’établir des coûts d'entrée sur ce marché (pour les différents contextes énergétiques considérés). Ensuite, les différentes applications de l’hydrogène ont été resituées en interaction avec l’ensemble du système énergétique à travers le modèle TIMES-PT et un cas d’étude portant sur le Portugal, permettant ainsi d’examiner le potentiel de couplage entre les secteurs énergétiques rendu possible par l’hydrogène. Ces travaux ont permis de qualifier l'attractivité des différents marchés, celui de la mobilité apparaissant comme le plus favorable.Nous nous sommes ensuite intéressés aux coûts requis sur l'ensemble de la chaîne d'approvisionnement en hydrogène afin de pénétrer le marché de la mobilité.Pour ce faire, nous avons utilisé des modèles avec une maille géographique et temporelle fine (GLAES, EuroPower et InfraGis), en commençant par l’étape de production. Nous avons étudié le rôle potentiel de l'hydrogène pour la fourniture de flexibilité au système électrique dans un contexte de forte pénétration des énergies renouvelables intermittentes en France. Nos résultats montrent que l’hydrogène pourrait permettre non seulement d’éviter d’écrêter la production d’énergies renouvelables (entre 1,4 et 7,9 TWh en fonction du scénario de capacité d’interconnexion), mais pourrait aussi mettre à profit l’énergie nucléaire disponible (bas carbone donc), évitant par-là d’imposer de fortes rampes de puissances aux centrales. Cependant, une attention particulière doit être accordée au taux d'utilisation de l'électrolyseur afin de maintenir les coûts de production d'hydrogène suffisamment bas.Enfin, nous nous sommes concentrés sur l’approvisionnement de l’hydrogène, depuis les sites de production jusqu’à l’utilisation pour la mobilité, la question de l’infrastructure étant un problème majeur entravant les investissements dans l’hydrogène. Cinq filières d’approvisionnement (transport et distribution) ont été développées à la maille régionale et comparées sur le plan économique pour le cas français. Nos résultats montrent que, lors des toutes premières phases de pénétration du marché (scénario 1%), il est plus intéressant de privilégier la production décentralisée Hydrogen… This simple, very abundant element holds great promise to contribute to the transition towards a cleaner future energy system, but under which techno-economic and political conditions? This thesis is a contribution to the assessment of the hydrogen penetration feasibility into the energy system, using a multi-model approach. The focus is put on low-carbon hydrogen, obtained by electrolysis.Our multi-regional analysis on the European, American, Chinese and Japanese energy context (presenting contrasted energy challenges) show that, with the current energy policies implemented which result in a modest penetration of hydrogen into the energy system, hydrogen may achieve approximately 3% of the effort that needs to be done by the four regions, in order to limit the increase of the temperature to 2°C, compared to preindustrial levels. We highlight in this thesis that blending hydrogen with natural gas, and thereby avoiding methane leakages to a certain extent, may represent a significant contribution in achieving the carbon mitigation goals.The hydrogen market analysis has been carried out following two steps. First, each market (industrial and energy-related) was tackled aside in order to propose market entry costs considering the four energy contexts and investigate the timeframe of the market penetration potential. Then, the different hydrogen applications were examined within the overall energy system through the TIMES-PT model (for a Portugal case study), allowing to investigate the hydrogen potential for energy sector coupling. Based on this work, the markets attractiveness was evaluated: mobility (using fuel cell vehicles) appears to be the most favourable.Then, we tackled the required costs over the whole hydrogen supply chain in order to enter the mobility market.To do so, we used temporally and spatially resolved models (GLAES, EuroPower and InfraGis) starting with the production side where we studied the hydrogen potential role in providing the electricity system with flexibility and the impact of such electrolysis operation on the hydrogen generation costs in the context of high shares of renewable energies in France. Our results show that hydrogen can contribute to improve the flexibility of the electric system by allowing avoiding renewable curtailment (between 1.4 and 7.9 TWh depending on the interconnection capacity scenario) but also by taking advantage of nuclear plant available energy (thereby avoiding nuclear ramping), the latter ensuring a low carbon and low cost electricity provision. However, a special attention needs to be dedicated to the utilisation rate of the electrolyser, to keep the hydrogen production costs low enough.Last but not least, we focused on how to link the hydrogen production sites and its final use for mobility applications, the delivery infrastructure being a major issue hampering the hydrogen investments. Five transport and delivery pathways were geographically designed and economically assessed, for the French case. According to our findings, during the very first market penetration phases (1% scenario), it is more interesting to start with decentralised production that proved to be less expensive for the whole pathway at this stage

APA, Harvard, Vancouver, ISO, and other styles

17

Reddy, Sharath. "Energy and Exergy Analysis of Chemical Looping Systems for Hydrogen and Sulfur Recovery." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1556069387739902.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

エドアード, ラマスホルヘ, and Jorge Eduardo Lamas de Anda. "Conceptual study on the energy independence of fuel cell cogeneration systems using solar energy." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12981850/?lang=0, 2016. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12981850/?lang=0.

Full text

Abstract:

この論文では従来電力系統から自立的に利用出来る太陽エネルギー及び燃料電池コジェネレーションシステムの徹底的な解析が述べられている。開発した水素マイクログリッドの燃料依存を最小化にする数理モデルを利用し日本社会でのさまざまなシナリオのシミュレーションが行なわれた。こういうシステムの実現性が従来水素燃料供給方法の審査及び日本の中型離島の事例研究で評価された。経済的な分析によって石油の価格が高い遠隔な地域では水素マイクログリッドは競争力があると分かった。 This thesis presents a thorough analysis on energy supply systems using solar energy and fuel cell cogeneration systems that can operate reliably and independently from the main power grid. A mathematical model to maximize fuel independence for hydrogen micro-grids is developed and simulated for various scenarios in Japanese communities. The viability of implementing such systems is assessed with a review of available hydrogen supply channels, and a study case for a remote Japanese island of medium size. An economic analysis of this study suggests that hydrogen micro-grids are economically competitive for energy supply in remote areas where oil prices are high. 博士(工学) Doctor of Philosophy in Engineering 同志社大学 Doshisha University

APA, Harvard, Vancouver, ISO, and other styles

19

Miró, Richart Paula. "Hydrogen-Abstraction, Energy Transfer and Exciplex Formation in Photoactive Systems Based on Bile Acids." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/64084.

Full text

Abstract:

[EN] Bile acids are a family of amphiphilic steroids that play a pivotal role in physiological functions such as elimination of cholesterol or solubilization of lipids. Chemically, they share a steroidal skeleton with an unusual cis fusion between rings A and B, a short lateral chain ending in a carboxylic acid moiety and different number of hydroxyl groups on the alpha-face. Hence, bile acids offer a versatile architecture that can be used to investigate photophysical processes of interest such as hydrogen atom transfer, through-bond energy trasfer, through-bond exciplex formation and DNA photodamage-related reactions. First, unmodified bile acids have been used to evaluate hydrogen atom trasfer to benzophenone-like triplet carbonyls. Dehydrogenation of bile acids at positions C-3 and/or C-7 by a radical-mediated mechanism from the excited state of benzophenone has been demonstrated. Moreover, synthesized lithocholic acid derivatives including benzophenone or carbazole as donors and a naphthalene, biphenyl or thymine as acceptors have been employed to investigate through-bond energy transfer and exciplex formation processes. Thus, energy transfer from benzophenone to naphthalene or biphenyl and extended through-bond exciplex formation in benzophenone/naphthalene and benzophenone/biphenyl linked systems has been demostrated by laser flash photolysis. Finally, bile acid derivatives incorporating one benzophenone and two thymine units with different degrees of freedom have been prepared to investigate the photochemical formation of oxetanes or thymine dimers. Photosensitized formation of cyclobutane pyrimidine dimers through the generation of a delocalized triplet excited state has been demonstrated in intermolecular systems, while oxetane formation is observed when the degrees of freedom are reduced. [ES] Los ácidos biliares son una familia de esteroides anfifílicos que juegan un papel clave en diferentes funciones fisiológicas tales como la eliminación del colesterol o la solubilización de lípidos. Su estructura química está constituida por un esqueleto esteroideo con una fusión cis poco común entre los anillos A y B, una cadena lateral corta que termina con una función ácida y un número variable de grupos hidroxilo en la cara alfa. Por tanto, los ácidos biliares ofrecen una estructura versátil que puede ser utilizada para investigar procesos fotofísicos de interés como abstracción de hidrógeno, transferencia de energía y formación de exciplejos a larga distancia o reacciones relacionadas con el daño fotoinducido al ADN. En esta Tesis, en primer lugar, los ácidos biliares naturales se han utilizado para evaluar la abstracción de hidrógeno a carbonilos triplete en compuestos derivados de la benzofenona, demostrándose la deshidrogenación de los ácidos biliares en las posiciones C-3 y/o C-7 por un mecanismo radicalario desde el mencionado triplete de la benzofenona. En segundo lugar, se han preparado derivados de ácido litocólico que incluyen los dadores benzofenona o carbazol y los aceptores naftaleno, bifenilo o timina, que a continuación se han utilizado para investigar los procesos de transferencia de energía y formación de exciplejo intramolecular a larga distancia. De hecho, en los sistemas benzofenona/naftaleno y benzofenona/bifenilo, se demostró por fotólisis de destello láser la transferencia de energía desde benzofenona a naftaleno o bifenilo y la formación de exciplejo a larga distancia. Por último, se han preparado derivados de ácidos bliares que incorporan una unidad de benzofenona y dos de timina en diferentes posiciones del esqueleto para investigar la influencia de los diferentes grados de libertad en la formación fotosensibilizada de oxetanos o dímeros de timina. Gracias a ellos, se ha demostrado la formación fotosensibilizada de dímeros ciclobutánicos pirimidínicos a través de la generación de estados excitados triplete deslocalizados en sistemas en los que la benzofenona es intermolecular, mientras que se observa formación de oxetanos cuando los grados de libertad se ven reducidos. [CAT] Els àcids biliars són una família d'esteroides anfifílics que juguen un paper clau en funcions fisiològiques com l'eliminació del colesterol o la solubilització de lípids. La seua estructura química està constituïda per un esquelet esteroïdal amb una fusió cis entre els anells A i B poc comuna, una cadena lateral curta que acaba amb una funció àcida i un nombre diferent de grups hidroxil en la cara alfa. D'aquesta manera, els àcids biliars ofereixen una estructura versàtil que pot ser utilitzada per investigar processos fotofísics d'interès com abstracció d'hidrogen, transferència d'energia i formació de exciplexes a llarga distància o reaccions relacionades amb el dany a l'ADN induït per llum. En primer lloc, els àcids biliars naturals s'han utilitzat per avaluar la abstracció d'hidrogen a carbonils triplets derivats de la benzofenona, demostrant-se la deshidrogenació dels àcids biliars en les posicions C-3 i/o C-7 per un mecanisme radicalari des de l'estat excitat de la benzofenona. A més, derivats d'àcid litocòlic que inclouen els donadors benzofenona o carbazol i els acceptors naftalé, bifenil o timina s'han utilitzat per investigar els processos de transferència d'energia i formació de exciplexe a llarga distància. En els sistemes benzofenona /naftalé i benzofenona/bifenil la fotòlisis làser va demostrar la transferència d'energia des de benzofenona a naftalé o bifenil i la formació d'exciplexe a llarga distància. Finalment, per tal d'investigar la formació fotosensibilitzada d'oxetans o dímers de timina, s'han preparat derivats d'àcids bliars que incorporen una unitat de benzofenona i dues de timina amb diferents graus de llibertat. La formació fotosensibilitzada de dímers ciclobutànics pirimidínics mitjançant la generació d'estats excitats triplet deslocalitzats ha estat demostrada en sistemes intermoleculars, mentre que la formació d'oxetans s'observa quan els graus de llibertat es veuen reduïts. Miró Richart, P. (2016). Hydrogen-Abstraction, Energy Transfer and Exciplex Formation in Photoactive Systems Based on Bile Acids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64084 TESIS

APA, Harvard, Vancouver, ISO, and other styles

20

Yao, Miao. "Exploiting Spatial Degrees-of-Freedom for Energy-Efficient Next Generation Cellular Systems." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77402.

Full text

Abstract:

This research addresses green communication issues, including energy efficiency, peak-to-average power ratio (PAPR) reduction and power amplifier (PA) linearization. Green communication is expected to be a primary goal in next generation cellular systems because it promises to reduce operating costs. The first key issue is energy efficiency of distributed antenna systems (DASs). The power consumption of high power amplifiers (HPAs) used in wireless communication systems is determined by the transmit power and drain efficiency. For unequal power allocation of orthogonal frequency division multiplexing (OFDM), the drain efficiency of the PA is determined by the PAPR and hence by the power distribution. This research proposes a PAPR-aware energy-efficient resource allocation scheme for joint orthogonal frequency division multiple access (OFDMA)/space division multiple access (SDMA) downlink transmission from DASs. Grouping-based SDMA is applied to exploit the spatial diversity while avoiding performance degradation from correlated channels. The developed scheme considers the impact of both system data rate and effective power consumption on the PAPR during resource allocation. We also present a suboptimal joint subcarrier and power allocation algorithm to facilitate implementation of power-efficient multi-channel wireless communications. By solving Karush-Kuhn-Tucker conditions, a closed-form solution for the power allocation of each remote radio head is obtained. The second key issue is related with PAPR reduction in the massive multiple-input multiple-output (MIMO) systems. The large number of PAs in next generation massive MIMO cellular communication system requires using inexpensive PAs at the base station to keep array cost reasonable. Large-scale multiuser (MU) MIMO systems can provide extra spatial degrees-of-freedom (DoFs) for PAPR reduction. This work applies both recurrent neural network (RNN)- and semidefinite relaxation (SDR)-based schemes for different purposes to reduce PAPR. The highly parallel structure of RNN is proposed in this work to address the issues of scalability and stringent requirements on computational times in PAPR-aware precoding problem. An SDR-based framework is proposed to reduce PAPR that accommodates channel uncertainties and intercell coordination. Both of the proposed structures reduce linearity requirements and enable the use of lower cost RF components for large-scale MU-MIMO-OFDM downlink. The third key issue is digital predistortion (DPD) in the massive MIMO systems. The primary source of nonlinear distortion in wireless transmitters is the PA, which is commonly modeled using polynomials. Conventional DPD schemes use high-order polynomials to accurately approximate and compensate for the nonlinearity of the PA. This is impractical for scaling to tens or hundreds of PAs in massive MIMO systems. This work therefore proposes a scalable DPD method, achieved by exploiting massive DoFs of next generation front ends. We propose a novel indirect learning structure which adapts the channel and PA distortion iteratively by cascading adaptive zero-forcing precoding and DPD. Experimental results show that over 70% of computational complexity is saved for the proposed solution, it is shown that a 3rd order polynomial with the new solution achieves the same performance as the conventional DPD using 11th order polynomial for a 100x10 massive MIMO configuration. Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

21

Alfredsson, Eva. "Green consumption energy use and carbon dioxide emission." Doctoral thesis, Umeå universitet, Kulturgeografi, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-80.

Full text

Abstract:

The aim of this thesis is to explore the quantitative potential to reduce energy requirements and CO2 emissions through changed patterns of consumption, given unchanged levels of consumption expenditure. The thesis question is analysed using a systems analysis approach which in this case means that life cycle assessment data on energy requirements and CO2 emissions related to household consumption are combined with a financial and behavioural analysis to make sure that the budget constraint is kept and that both the first and second order effects of adopting a green consumption pattern are analysed. The budget constraints are kept using a general linear model. By using marginal propensities to spend to direct the reallocation of saved or deficit money calculated utility is maintained as far as possible. Further, investigations explore the impact of individual household demographic characteristics and geographic context on household consumption patterns, energy requirements and CO2 emissions. The key result of this thesis is that changed household behaviour, choosing “green“ products and energy efficient technology will not make a big difference. What can be achieved in the short time perspective by adopting an almost completely green consumption pattern and energy efficient technology is a reduction of energy requirements by around 8% and CO2 emissions by around 13%. With a longer time perspective and further technological change that provides additional possibilities to move consumption patterns in a greener direction, the effect on energy requirements and CO2 emissions is still fairly small. By 2020, the potential to reduce energy requirements is around 13% and CO2 emissions around 25%. In the most extreme scenario (2050), the scope for reducing energy requirements is 17% and for CO2 emissions 30%. All these reductions will be outpaced by growth in income almost as soon as they are implemented. Of policy relevance the results reveal that very limited impact can be expected by a policy relying on greener consumption patterns, whether adopted voluntarily or as a result of incentives such as tax changes. Such a policy cannot achieve more than a small and temporary reduction to growth in energy requirements and CO2 emissions. It is also shown that, prescribing specific consumption patterns as a means of reducing energy requirements and CO2 emissions has to be done with care. This is illustrated by one of the experiments in which adopting a partly green consumption pattern, a green diet, in fact increased total energy requirements and CO2 emissions. This, and the results of all the other experiments show the importance of applying a systems approach. It demonstrates that life cycle data alone are irrelevant for assessing the total effects of adopting green consumption patterns. Further research on the potential to reduce energy requirements and CO2 emissions thus primarily needs to better capture system wide effects rather than to improve on, and fine tune the measurement of the energy requirements and CO2 emissions related to individual products.

APA, Harvard, Vancouver, ISO, and other styles

22

Coma, Arpón Julià. "Green roofs and vertical greenery systems as passive tools for energy efficiency in buildings." Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/399726.

Full text

Abstract:

D'acord amb les Perspectives de Tecnologia Energètica del 2016, la demanda d'energia primària i les emissions de carboni han de reduirse en més d'un 30% per a l'any 2050. Una manera d'aconseguir-ho, es per mitjà de regulacions que millorin el rendiment tèrmic de la pell de l'edifici. En aquest context, durant l’última dècada els sostres verds i sistemes verds verticals implementats en la pell dels edificis han esdevingut prometedors sistemes passius d’estalvi d'energètic i de reducció de les emissions de CO2 en els entorns urbans. Per tant, els principals objectius d'aquesta tesi doctoral són: analitzar l'eficiència energètica dels sostres verds extensius i sistemes verds verticals per tal d'avaluar el seu potencial com a sistemes passius d'estalvi d'energia. Altrament, la capacitat d'aïllament acústic proporcionat per una façana verda i un mur vegetal, també formen part d'aquesta tesi. A més de proporcionar dades quantitatives per fer front a la manca de resultats experimentals en la literatura, aquesta tesi també es centra en l'anàlisi de l'impacte mediambiental dels sostres verds extensius per tal d'estudiar la seva sostenibilitat. De acuerdo con las Perspectivas de Tecnología Energética de 2016, la demanda de energía primaria y las emisiones de carbono deben reducirse en más de un 30% para el año 2050. Una manera de conseguirlo es por medio de regulaciones que mejoren el rendimiento térmico de la piel del edificio. En este contexto, durante la última década los techos verdes y sistemas verdes verticales implementados en la piel de los edificios se han convertido en prometedores sistemas pasivos de ahorro energético y de reducción de las emisiones de CO2 en los entornos urbanos. Por tanto, los principales objetivos de esta tesis doctoral son: analizar la eficiencia energética de los techos verdes extensivos y sistemas verdes verticales para evaluar su potencial como sistemas pasivos de ahorro energético. Por otro lado, la capacidad de aislamiento acústico proporcionado por una fachada verde y un muro vegetal, también forman parte de esta tesis. Además de proporcionar datos cuantitativos para hacer frente a la falta de resultados experimentales en la literatura, esta tesis también se centra en el análisis del impacto medioambiental de los techos verdes extensivos para estudiar su sostenibilidad. According to the Energy Technology Perspectives 2016, the primary energy demand and carbon emissions should be reduced over 30% by 2050. One way to achieve the EU prespectives are the regulations that enhance the thermal performance of the building skin. Within this context, the use of urban green infrastructures (green roofs and vertical greenery systems) on building envelopes have become more popular during the last decade as promising passive solutions regarding the energy consumption and CO2 emissions in built environments. Therefore, the main objectives of this PhD thesis are: to analyse the energy efficiency of extensive green roofs and vertical greenery systems in order to evaluate their potential as a passive energy saving systems. In addition, the sound insulation capacity provided by two different vertical greenery systems (green facades and green walls or living walls) was also part of the PhD thesis. Besides providing quantitative data to address the lack of experimental results in the literature, this thesis is also focused on analysing the environmental impact of extensive green roofs in order to study their sustainability.

APA, Harvard, Vancouver, ISO, and other styles

23

ÖHMAN, AXEL. "Green hydrogen production at Igelsta CHP plant : A techno-economic assessment conducted at Söderenergi AB." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299434.

Full text

Abstract:

The energy transition taking place in various parts of the world will have many effects on the current energy systems as an increasing amount of intermittent power supply gets installed every year. In Sweden, just as many other countries, this will cause both challenges and opportunities for today´s energy producers. Challenges that may arise along with an increasingly fluctuating electricity production include both power deficits at certain times and regions but also hours of over-production which can cause electricity prices to drop significantly. Such challenges will have to be met by both dispatchable power generation and dynamic consumption. Conversely, actors prepared to adapt to the new climate by implementing new technologies or innovative business models could benefit from the transition towards a fully renewable energy system. This thesis evaluates the techno-economic potential of green hydrogen production at a combined heat and power plant with the objective to provide decision support to a district heat and electricity producer in Sweden. It was in the company’s interest to investigate how hydrogen production could help reduce the production cost of district heat as well as contribute to the reduction of greenhouse gases. In the project, two separate business models: Power-to-gas and Power-to-power were evaluated on the basis of technical and economic performance and environmental impact. To do this, a mathematical model of the CHP plant and the hydrogen systems was developed in Python which optimizes the operation based on costs. The business models were then simulated for two different years with each year representing a distinctly different electricity market situation. The main conclusions of the study show that Power-to-gas could already be profitable at a hydrogen retail price of 40 SEK per kg, which is the projected retail price for the transportation sector. The demand today is however limited but is expected to grow fast in the near future, especially within heavy transportation. Another limiting factor for hydrogen production showed to be the availability of storage space, as hydrogen gas even at pressures up to 200 bar require large volumes. Power-to-power for frequency regulation was found to not be economically justifiable as the revenue for providing grid services could not outweigh the high investment costs for any of the simulated years. This resulted in a high levelized cost of energy at over 3000 SEK per MWh which was mostly due to the low capacity factor of the power-to-power system. Finally, green hydrogen has the potential of replacing fossil fuels in sectors that is difficult to reach with electricity, for example long-haul road transport or the shipping industry. Therefore, green hydrogen production in large scale could help decarbonize many of society’s fossil-heavy segments. By also serving as a grid-balancer, hydrogen production in a power-to-gas process has the potential of becoming an important part of a renewable energy system. Energiomställningen som äger rum i olika delar av världen kommer att ha många effekter på de nuvarande energisystemen eftersom en ökande mängd väderberoende kraftproduktion installeras varje år. I Sverige, precis som många andra länder, kommer detta att medföra både utmaningar och möjligheter för dagens energiproducenter. Utmaningar som kan uppstå tillsammans med en alltmer fluktuerande elproduktion inkluderar både kraftunderskott vid vissa tider och regioner men också timmar av överproduktion som kan få elpriserna att sjunka avsevärt. Sådana utmaningar måste mötas av både planerbar kraftproduktion och dynamisk konsumtion. Omvänt kan aktörer som är beredda att anpassa sig till det nya klimatet genom att implementera ny teknik eller innovativa affärsmodeller dra nytta av övergången till ett helt förnybart energisystem. Denna rapport utvärderar den tekno-ekonomiska potentialen för produktion av grön vätgas vid ett kraftvärmeverk med målet att ge beslutsstöd till en fjärrvärme- och elproducent i Sverige. Det var i företagets intresse att undersöka hur vätgasproduktion kan bidra till att sänka produktionskostnaden för fjärrvärme samt bidra till att minska växthusgaser. I projektet utvärderades två separata affärsmodeller: Power-to-gas och Power-to-power baserat på teknisk och ekonomisk prestanda samt miljöpåverkan. För att kunna göra detta utvecklades en matematisk modell i Python av kraftvärmeverket och vätgassystemen som optimerar driften baserat på kostnader. Affärsmodellerna simulerades sedan för två olika års elpriser för att undersöka modellens prestanda i olika typer av elmarknader. De viktigaste slutsatserna i studien visar att Power-to-gas redan kan vara lönsamt till ett vätgaspris på 40 SEK per kg, vilket är det förväntade marknadspriset på grön vätgas for transportsektorn. Efterfrågan är idag begränsad men förväntas växa snabbt inom en snar framtid, särskilt inom tung transport. En annan begränsande faktor för vätgasproduktion visade sig vara tillgången på lagringsutrymme, eftersom vätgas även vid tryck upp till 200 bar kräver stora volymer. Power-to-power för frekvensreglering visade sig inte vara ekonomiskt försvarbart, eftersom intäkterna för att tillhandahålla nättjänster inte kunde uppväga de höga investeringskostnaderna under några av de simulerade åren. Detta resulterade i en hög LCOE på över 3000 SEK per MWh, vilket främst berodde på Power-to-power-systemets låga utnyttjandegrad. Slutligen kan det sägas att grön vätgas har stor potential att ersätta fossila bränslen i sektorer som är svåra att elektrifiera, exempelvis tunga vägtransporter eller sjöfart. Därför kan storskalig grön vätgasproduktion hjälpa till att dekarbonisera många av samhällets fossiltunga segment. Genom att dessutom fungera som balansering har väteproduktion i en Power-to-gas-process potential att bli en viktig del av ett system med stor andel förnybar energi.

APA, Harvard, Vancouver, ISO, and other styles

24

Sanchez, Antonio. "Energy management in electric systems fed by fuel cell stacks." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00590217.

Full text

Abstract:

The growth of distributed energy resources together with the incorporation of new technologies in the generation and storage of energy are imposing new control and operational strategies. Due to its storage capability and that it is considered to be clean energy; fuel cell (FC) is one of the most promissory technologies as a stationary energy source in micro grids and also in transportation applications. Therefore, two main issues are addressed in this work; the conception, design, and setup of a fully instrumented test bench for proton exchange membrane (PEM) FC stacks and the design and experimental test of a new dynamic energy-exchange control strategy for multi source and multi load systems. To define the test bench instrument requirements, in the first part a complete dynamic model review is given. In the next section, relevant information regarding the setup of the FC test bench design and implementation is included, i.e., specification criteria of the instruments and acquisition and data display system. Some experimental results are performed in order to demonstrate the potentialities of the setup. In the following chapter, a new dynamic energy exchange control strategy (DSER) is introduced and tested in a two port system via simulation and experimentation. In order to establish a comparison and integrate the DSER in a FC application, in the fifth chapter a three port system - including a static model of FC - and two different control approaches, are tested via simulation. The thesis is closed with some concluding remarks and some potential research topics generated from this work.

APA, Harvard, Vancouver, ISO, and other styles

25

Martino, Drew J. "Evaluation of Electrochemical Storage Systems for Higher Efficiency and Energy Density." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/470.

Full text

Abstract:

Lack of energy storage is a key issue in the development of renewable energy sources. Most renewables, especially solar and wind, when used alone, cannot sustain a reliably constant power output over an extended period of time. These sources generally generate variable amounts of power intermittently, therefore, an efficient electrical energy storage (EES) method is required to better temporally balance power generation to power consumption. One of the more promising methods of electrical energy storage is the unitized regenerative fuel cell (UFRC.) UFRCs are fuel cells that can operate in a charge-discharge cycle, similar to a battery, to store and then to subsequently release power. Power is stored by means of electrolysis while the products of this electrolysis reaction can be recombined as in a normal fuel cell to release the stored power. A major advantage of UFRCs over batteries is that storage capacity can be decoupled from cell power, thus reducing the potential cost and weight of the cell unit. Here we investigate UFRCs based on hydrogen-halogen systems, specifically hydrogen-bromine, which has potential for improved electrode reaction kinetics and hence cheaper catalysts and higher efficiency and energy density. A mathematical model has been developed to analyze this system and determine cell behavior and cycle efficiency under various conditions. The conventional H2-Br2 URFCs, however also so far have utilized Pt catalysts and Nafion membranes. Consequently, a goal of this work was to explore alternate schemes and materials for the H2-Br2 URFC. Thus, three generations of test cells have been created. The first two cells were designed to use a molten bromide salt, ionic liquid or anion exchange membrane as the ion exchange electrolyte with the liquids supported on a porous membrane. This type of system provides the potential to reduce the amount of precious metal catalyst required, or possibly eliminate it altogether. Each cell showed improvement over the previous generation, although the results are preliminary. The final set of results are promising for anion exchange membranes on a cost basis compared Nafion. Another promising energy storage solution involves liquid methanol as an intermediate or as a hydrogen carrier. An alternative to storing high-pressure hydrogen is to produce it on-board/on-site on demand via a methanol electrocatalytic reformer (eCRef), a PEM electrolyzer in which methanol-water coelectrolysis takes place. Methanol handling, storage, and transportation is much easier than that for hydrogen. The hydrogen produced via methanol eCref may then be used in any number of applications, including for energy storage and generation in a standard H2-O2 PEM fuel cell. The mathematical modeling and analysis for an eCref is very similar to that of the HBr URFC. In this work, a comprehensive model for the coelectrolysis of methanol and water into hydrogen is created and compared with experimental data. The performance of the methanol electrolyzer coupled with a H2-O2 fuel cell is then compared for efficiency to that of a direct methanol fuel cell data and was found to be superior. The results suggest that an efficient and small paired eCRef-fuel cell system is potentially be a cheaper and more viable alternative to the standard direct methanol fuel cell. Both the H2-Br2 URFC and the methanol eCref in combination with a H2-O2 fuel cell have significant potential to provide higher energy efficiency and energy density for EES purposes.

APA, Harvard, Vancouver, ISO, and other styles

26

Suamir, I. Nyoman. "Integration of trigeneration and CO2 based refrigeration systems for energy conservation." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6971.

Full text

Abstract:

Food retail with large supermarkets consumes significant amounts of energy. The environmental impact is also significant because of the indirect effect from CO2 emissions at the power stations and due to the direct effect arising from refrigerant leakage to the atmosphere. The application of trigeneration (local combined heat, power and refrigeration) can provide substantial improvements in the overall energy efficiency over the conventional supermarket energy approach of separate provision of electrical power and thermal energy. The use of natural refrigerants such as CO2 offers the opportunity to reduce the direct impacts of refrigeration compared to conventional systems employing HFC refrigerants that possess high global warming potential. One approach through which the overall energy efficiency can be increased and the environmental impacts reduced, is through the integration of trigeneration and CO2 refrigeration systems where the cooling generated by the trigeneration system is used to condense the CO2 refrigerant in a cascade arrangement. This research project investigates experimentally and theoretically, through mathematical modelling and simulation, such a system and its potential application to supermarkets. A small size CO2 refrigeration system for low and medium food temperature applications was designed and constructed to enable it to be integrated with an existing trigeneration system in the refrigeration laboratory at Brunel University to form an integrated trigeneration and CO2 refrigeration test facility. Prior to the construction, the design of the system was investigated using mathematical models developed for this purpose. The simulations included the CO2 refrigeration system, CO2 evaporator coils and the integration of the trigeneration and CO2 refrigeration systems. The physical size of the design and component arrangement was also optimised in a 3D AutoCAD model. A series of experimental tests were carried out and the results showed that the medium temperature system could achieve a very good COP, ranging from 32 to 60 due to the low pumping power requirement of the liquid refrigerant. The low temperature system performed with average steady state COP of 4, giving an overall refrigeration system COP in the range between 5.5 and 6. Mathematical models were also developed to investigate the application of the integrated trigeneration and CO2 refrigeration system in a case study supermarket. The models were validated against test results in the laboratory and manufacturers’ data. The fuel utilisation efficiency and environmental impacts of different trigeneration and CO2 refrigeration arrangements were also evaluated. The results indicated that a system comprising of a sub-critical CO2 refrigeration system integrated with a trigeneration system consisting of a micro-turbine based Combined Heat and Power (CHP) unit and ammonia-water absorption refrigeration system could provide energy savings of the order of 15% and CO2 emission savings of the order of 30% compared to conventional supermarket energy systems. Employing a trigeneration system with a natural gas engine based CHP and Lithium Bromide-Water sorption refrigeration system, could offer energy savings of 30% and CO2 emission savings of 43% over a conventional energy system arrangement. Economic analysis of the system has shown a promising payback period of just over 3 years compared to conventional systems.

APA, Harvard, Vancouver, ISO, and other styles

27

Estaña, Garcia Guillermo, and Julian Iñigo Ruiz. "Feasibility of converting a Science Park in a cold climate into an “off-grid” facility using renewable energies and seasonal storage systems." Thesis, Högskolan i Gävle, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-30417.

Full text

Abstract:

The collateral effects of fossil fuels push humanity to seek solutions to these adversities. Energy efficiency and renewable energies have gone from being almost imaginary concepts to necessary. Several studies have shown that self-sufficiency through photovoltaic systems and wind energy is possible. In addition, it is necessary a storage of the surpluses of both since it increases notably the efficiency of these systems and supposes to the short/medium term a saving of money in the consumer. Due to the mentioned before, the aim of the thesis is to convert a science park located in a cold climate such as Sweden into a complex that does not depend energetically on external sources. For this purpose, a series of data from the park were first collected and then simulated and optimised using the HOMER software for different energy configurations. At the same time, a computer code was created in MatLab to enable the energy produced to be used responsibly. The proposed system consists of PV panels, wind turbines and a battery. Thanks to it, a 64 % renewable fraction is achieved, which means a reduction of 27.45 tons of CO2 per year. In addition, through the energy management system created, the electricity contract is reduced, reducing the purchase of electricity during peak hours. It is concluded that the implementation of both proposed systems contributes significantly to the achievement of the sustainable goals set for 2 030 by the main world leaders, even though a total disconnection with the electrical grid has not been achieved.

APA, Harvard, Vancouver, ISO, and other styles

28

Reissner, Alexander. "Metal Hydrides as Enabling Technology for the use of Hydrogen-Based Energy Storage Systems on Telecommunication Satellites." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-229226.

Full text

Abstract:

Next generation telecommunication satellites will demand an increasing amount of power in the range of 30 kW or more within the next 10 years. Battery technology that can sustain 30 kW for an eclipse length of up to 72 minutes will represent a major impact on the total mass of the satellite, even with new Li-ion battery technologies. Regenerative fuel cell systems (RFCS) were identified years ago as a possible alternative to rechargeable batteries. Nevertheless, one major drawback was identified by several independent system studies, namely the need to dissipate large amounts of heat from the fuel cell (FC) during eclipse. This in turn requires massive thermal hardware (mainly large radiators) that can contribute up to 50% of the system mass. In order to overcome this issue, the use of metal hydrides (MH) as combined hydrogen and heat storage system was suggested as a starting point of the research presented in this thesis. During eclipse the FC must dissipate waste heat, and at the same time the MH tank must absorb heat in order to desorb hydrogen. Rather than dissipating the waste heat from the FC directly through a radiator, it can be stored solely, or partly, in the MH tank, to be dissipated during Equinox, with a 20 times slower rate, requiring a radiator with significantly less volume and mass. This thesis aims to present the potential of using such MH storage tanks to alternately store hydrogen and waste heat from the FC on-board a spacecraft, investigated by theoretical and experimental means. The model application for the MH tank technology considered in this thesis is a 39 kW telecommunication satellite. Nevertheless, the derived results are to be considered a generic outcome and can be translated or scaled to many other applications Es kann davon ausgegangen werden, dass der Trend hin zu Telekommunikationssatelliten mit immer höherer Leistung in den nächsten 10 Jahren zu Satelliten-Plattformen mit 30kW und mehr führen wird. Batterien, welche eine Leistung von 30kW für Eklipse-Längen von 72 Minuten zur Verfügung stellen müssen, werden daher einen immer größeren Einfluss auf die Gesamtmasse des Satelliten haben. Regenerative Brennstoffzellensysteme wurden daher schon vor Jahren als mögliche Alternative zu wieder aufladbaren Batterien untersucht. Mehrere unabhängige Studien sind zu dem Schluss gekommen, dass die größte Problematik in der Einführung von Brennstoffzellensystemen auf Satelliten darin besteht, die relativ großen Mengen an Abwärme effizient abzustrahlen. Die Radiatoren, die hierfür benötigt werden können 50% der Masse des Gesamtsystems ausmachen. Um dieses Problem zu überwinden wurde als Startpunkt der vorliegenden Arbeit die Nutzung von Metallhydriden als kombinierter Wasserstoff- und Wärmespeicher vorgeschlagen. Während sich der Satellit im Erdschatten befindet produziert die Brennstoffzelle Abwärme, während zur gleichen Zeit der Metallhydrid-Tank Wärme benötigt um Wasserstoff freizusetzen. Die Abwärme der Brennstoffzelle muss daher nicht direkt über Radiatoren abgestrahlt werden, sondern wird von Metallhydrid-Tank absorbiert um dann während dem restlichen Erdumlauf 20 mal langsamer mit einem deutlich kleinerem und leichteren Radiator abgegeben werden zu können. Diese Arbeit hat zum Ziel, das durch analytische und experimentelle Methoden untersuchte Potential der Anwendung einer solchen Technologie auf Satelliten zu präsentieren. Die Modellapplikation für diese Arbeit ist ein 39kW Telekommunikationssatellit. Die Ergebnisse lassen sich allerdings auch auf andere Anwendungen skalieren und übertragen

APA, Harvard, Vancouver, ISO, and other styles

29

Orgerie, Anne-Cécile. "An Energy-Efficient Reservation Framework for Large-Scale Distributed Systems." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2011. http://tel.archives-ouvertes.fr/tel-00672130.

Full text

Abstract:

Over the past few years, the energy consumption of Information and Communication Technologies (ICT) has become a major issue. Nowadays, ICT accounts for 2% of the global CO2 emissions, an amount similar to that produced by the aviation industry. Large-scale distributed systems (e.g. Grids, Clouds and high-performance networks) are often heavy electricity consumers because -- for high-availability requirements -- their resources are always powered on even when they are not in use. Reservation-based systems guarantee quality of service, allow for respect of user constraints and enable fine-grained resource management. For these reasons, we propose an energy-efficient reservation framework to reduce the electric consumption of distributed systems and dedicated networks. The framework, called ERIDIS, is adapted to three different systems: data centers and grids, cloud environments and dedicated wired networks. By validating each derived infrastructure, we show that significant amounts of energy can be saved using ERIDIS in current and future large-scale distributed systems.

APA, Harvard, Vancouver, ISO, and other styles

30

Wang, Qiang. "Performance and power modeling of GPU systems with dynamic voltage and frequency scaling." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/814.

Full text

Abstract:

To address the ever-increasing demand for computing capacities, more and more heterogeneous systems have been designed to use both general-purpose and special-purpose processors. The huge energy consumption of them raises new environmental concerns and challenges. Besides performance, energy efficiency is another key factor to be considered by system designers and consumers. In particular, contemporary graphics processing units (GPUs) support dynamic voltage and frequency scaling (DVFS) to balance computational performance and energy consumption. However, accurate and straightforward performance and power estimation for a given GPU kernel under different frequency settings is still lacking for real hardware, which is essential to determine the best frequency configuration for energy saving. In this thesis, we investigate how to improve the energy efficiency of GPU systems by accurately modeling the effects of GPU DVFS on the target GPU kernel. We also propose efficient algorithms to solve the communication contention problem in scheduling multiple distributed deep learning (DDL) jobs on GPU clusters. We introduce our studies as follows. First, we present a benchmark suite EPPMiner for evaluating the performance, power, and energy of different heterogeneous systems. EPPMiner consists of 16 benchmark programs that cover a broad range of application domains, and it shows a great variety in the intensity of utilizing the processors. We have implemented a prototype of EPPMiner that supports OpenMP, CUDA, and OpenCL, and demonstrated its usage by three showcases. The showcases justify that GPUs provide much better energy efficiency than other types of computing systems, and especially illustrate the effectiveness of GPU Dynamic Voltage and Frequency Scaling (DVFS) on the energy efficiency of GPU applications. Second, we reveal a fine-grained analytical model to estimate the execution time of GPU kernels with both core and memory frequency scaling. Compared to the cycle-level simulators, which are too slow to apply on real hardware, our model only needs one-off micro-benchmarks to extract a set of hardware parameters and kernel performance counters without any source code analysis. Our experimental results show that the proposed performance model can capture the kernel performance scaling behaviors under different frequency settings and achieve decent accuracy. Third, we design a cross-benchmarking suite, which simulates kernels with a wide range of instruction distributions. The synthetic kernels generated by this suite can be used for model pre- training or as supplementary training samples. We then build machine learning models to predict the execution time and runtime power of a GPU kernel under different voltage and frequency settings. Validated on three modern GPUs with a wide frequency scaling range, by using a collection of 24 real application kernels, the model trained only with our cross-benchmarking suite is able to achieve considerably accurate results. At last, we establish a new DDL job scheduling framework which organizes DDL jobs as Directed Acyclic Graphs (DAGs) and considers communication contention between nodes. We then propose an efficient job placement algorithm, Least-Workload-First- (LWF-), to balance the GPU utilization and consolidate the allocated GPUs for each job. When scheduling the communication tasks, we propose Ada-SRSF for the DDL job scheduling problem to address the communication contention issue. Our simulation results show that LWF- achieves up to 1.59x improvement over the classical first-fit algorithms. More importantly, Ada-SRSF reduces the average job completion time by up to 36.7%, as compared to the solutions of either avoiding all the communication contention or accepting all of it

APA, Harvard, Vancouver, ISO, and other styles

31

Gidén, Hember Amanda. "Understanding Green Energy Technology : Learning Processes in the Development of the Ground Source Heat Pump." Thesis, Uppsala universitet, Byggteknik och byggd miljö, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414021.

Full text

Abstract:

The aim of this thesis is to increase the understanding of small-scale green energy technology development. In the transition towards a fossil free energy system, heat pumps are a low emission heating alternative. Contrary to other types of new small-scale green energy technology such as solar cells and electric vehicles, heat pumps are established on the Swedish market, with more than half the share of single family buildings. This makes it possible to study an example of a mature technology, and that knowledge could be used in the development and deployment of other technologies with similar small-scale green characteristics. The type of heat pump technology studied is ground source heat pumps, and their development is explored from an economic and performance perspective, using the concept of learning. Learning tracks how a product develops for each doubling of units produced. The results show that the efficiency has increased by a learning rate of 2.8 %. When the effects of a low-temperature heating system is included, the learning rate is even higher, 5.8 %. The efficiency improvement is mainly due to new and more expensive components, which has resulted in a price increase. Even if the price slightly decreased until 2008, it has increased with 29 % since. Nevertheless, the ground source heat pump is profitable compared to several other heating technologies. The most important factors underpinning the development are regulations, competition among manufacturers and research.

APA, Harvard, Vancouver, ISO, and other styles

32

Guan, Tingting. "Biomass-fuelled PEM FuelCell systems for small andmedium-sized enterprises." Doctoral thesis, KTH, Energiprocesser, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176633.

Full text

Abstract:

Biomass-fuelled proton exchange membrane fuel cells (PEMFCs) offer asolution for replacing fossil fuel for hydrogen production. Through using thebiomass-derived hydrogen as fuel, PEMFCs may become an efficient andsustainable energy system for small and medium-sized enterprises. The aim ofthis thesis is to evaluate the performance and potential applications of biomassfuelledPEMFC systems which are designed to convert biomass to electricity andheat. Biomass-fuelled PEMFC systems are simulated by Aspen plus based ondata collected from experiments and literature.The impact of the quality of the hydrogen-rich gas, anode stoichiometry, CH4content in the biogas and CH4 conversion rate on the performance of the PEMFCis investigated. Also, pinch technology is used to optimize the heat exchangernetwork to improve the power generation and thermal efficiency.For liquid and solid biomass, anaerobic digestion (AD) and gasification (GF),respectively, are relatively viable and developed conversion technologies. ForAD-PEMFC, a steam reformer is also needed to convert biogas to hydrogen-richgas. For 100 kWe generation, the GF-PEMFC system yields a good technicalperformance with 20 % electrical efficiency and 57 % thermal efficiency,whereas the AD-PEMFC system only has 9 % electrical efficiency and 13 %thermal efficiency. This low efficiency is due to the low efficiency of theanaerobic digester (AD) and the high internal heat consumption of the AD andthe steam reformer (SR). For the environmental aspects, the GF-PEMFC systemhas a high CO2 emissions offset factor and the AD-PEMFC system has anefficient land-use.The applications of the biomass-fuelled PEMFC systems are investigated on adairy farm and an olive oil plant. For the dairy farm, manure is used as feedstockto generate biogas through anaerobic digestion. A PEMFC qualified for 40 %electrical efficiency may generate 360 MWh electricity and 680 MWh heat peryear to make a dairy farm with 300 milked cows self-sufficient in a sustainableway. A PEMFC-CHP system designed for an olive oil plant generating annual 50000 m3 solid olive mill waste (SOMW) and 9 000 m3 olive mill waste water(OMW) is simulated based on experimental data from the Biogas2PEM-FCproject1. After the optimization of the heat exchanger network, the PEMFC-CHP system can generate 194 kW electricity which corresponds to 62 % of the totalelectricity demand of the olive oil plant.The economic performance of the PEMFC and biogas-fuelled PEMFC areassessed roughly including capital, operation & maintenance (O&M) costs of thebiogas plant and the PEMFC-CHP, the cost of heat and electricity, and the valueof the digestate as fertilizer. QC 20151109

APA, Harvard, Vancouver, ISO, and other styles

33

Mei, Xinxin. "Energy conservation techniques for GPU computing." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/298.

Full text

Abstract:

The emerging general purpose graphics processing units (GPGPU) computing has tremendously speeded up a great variety of commercial and scientific applications. The GPUs have become prevalent accelerators in current high performance clusters. Though the computational capacity per Watt of the GPUs is much higher than that of the CPUs, the hybrid GPU clusters still consume enormous power. To conserve energy on this kind of clusters is of critical significance. In this thesis, we seek energy conservative computing on the GPU accelerated servers. We introduce our studies as follows. First, we dissect the GPU memory hierarchy due to the fact that most of the GPU applications are suffering from the GPU memory bottleneck. We find that the conventional CPU cache models cannot be applied on the modern GPU caches, and the microbenchmarks to study the conventional CPU cache become invalid for the GPU. We propose the GPU-specified microbenchmarks to examine the GPU memory structures and properties. Our benchmark results verify that the design goal of the GPU has transformed from pure computation performance to better energy efficiency. Second, we investigate the impact of dynamic voltage and frequency scaling (DVFS), a successful energy management technique for CPUs, on the GPU platforms. Our experimental results suggest that GPU DVFS is still promising in conserving energy, but the patterns to save energy strongly differ from those of the CPU. Besides, the effect of GPU DVFS depends on the individual application characteristics. Third, we derive the GPU DVFS power and performance models from our experimental results, based on which we find the optimal GPU voltage and frequency setting to minimize the energy consumption of a single GPU task. We then study the problem of scheduling multiple tasks on a hybrid CPU-GPU cluster to minimize the total energy consumption by GPU DVFS. We design an effective offline scheduling algorithm which can reduce the energy consumption significantly. At last, we combine the GPU DVFS and dynamic resource sleep (DRS), another energy management technique, to further conserve the energy, for the online task scheduling on hybrid clusters. Though the idle energy consumption increases significantly compared to the offline problem, our online scheduling algorithm still achieves more than 30% of energy conservation with appropriate runtime GPU DVFS readjustments.

APA, Harvard, Vancouver, ISO, and other styles

34

Uluoglu, Arman. "Solar-hydrogen Stand-alone Power System Design And Simulations." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611884/index.pdf.

Full text

Abstract:

In this thesis, solar-hydrogen Stand-Alone Power System (SAPS) which is planned to be built for the emergency room of a hospital is designed. The system provides continuous, off-grid electricity during the whole period of a year without any external electrical power supply. The system consists of Photovoltaic (PV) panels, Proton Exchange Membrane (PEM) based electrolyzers, PEM based fuel cells, hydrogen tanks, batteries, a control mechanism and auxiliary equipments such as DC/AC converters, water pump, pipes and hydrogen dryers. The aim of this work is to investigate the optimal system configuration and component sizing which yield to high performance and low cost for different user needs and control strategies. TRNSYS commercial software is used for the overall system design and simulations. Numerical models of the PV panels, the control mechanism and the PEM electrolyzers are developed by using theoretical and experimental data and the models are integrated into TRNSYS. Overall system models include user-defined components as well as the default software components. The electricity need of the emergency room without any shortage is supplied directly from the PV panels or by the help of the batteries and the fuel cells when the solar energy is not enough. The pressure level in the hydrogen tanks and the overall system efficiency are selected as the key design parameters. The major component parameters and various control strategies affecting the hydrogen tank pressure and the system efficiency are analyzed and the results are presented.

APA, Harvard, Vancouver, ISO, and other styles

35

Aquino, Eddie Villanueva. "PREDICTING BUILDING ENERGY PERFORMANCE: LEVERAGING BIM CONTENT FOR ENERGY EFFICIENT BUILDINGS." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1077.

Full text

Abstract:

Reducing and managing the environmental impacts of building structures has become a priority of building stakeholders and within the architecture, engineering and construction (AEC) community; although, conflicting approaches and methods to combat the issues are present. For example, green building standards are widespread throughout the world; however each one has its own characteristics and consequently its own specific requirements. While all have proven to be effective rating systems and have similar requirements, the distinguishing characteristic that separates them is their treatment of performance and prescriptive metrics. The feature they all severely lack or currently limit is the inclusion of strict engineering evaluation through energy simulations; hence, the reason why they fail to offer procedural steps to meet performance metrics. How can design professionals design energy efficient buildings with such constraints? Fortunately, advances in technology have allowed design professionals access to content found in Building Information Modeling (BIM). However, extracting pertinent information for specific use in energy analysis is problematic because BIM software currently available is filled with interoperability issues when placed in external software for energy analysis and energy analysis software itself is created with many assumptions that affect the tabulated energy results. This research investigates current building rating systems, determines how current professionals meet energy requirements, and prove that it is possible to create an add-on feature to Autodesk Revit that will allow design professionals to extract the needed information to meet energy goals with actual prescribed methods of mechanical systems selection and evaluation.

APA, Harvard, Vancouver, ISO, and other styles

36

Gibrael, Nemir, and Hamse Hassan. "HYDROGEN-FIRED GAS TURBINE FOR POWER GENERATION WITH EXHAUST GAS RECIRCULATION : Emission and economic evaluation of pure hydrogen compare to natural gas." Thesis, Mälardalens högskola, Framtidens energi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-42306.

Full text

Abstract:

The member states of European Union aim to promote the reduction of harmful emissions. Emissions from combustion processes cause effects on human health and pose environmental issues, for example by increasing greenhouse effect. There are two ways to reduce emissions; one is to promote renewable energy sources and the other to utilize more effectively the available fossil fuels until a long-term solution is available. Hence, it is necessary to strive for CO2 mitigation technologies applied to fossil fuels. Low natural gas prices together with high energy efficiency have made gas turbines popular in the energy market. But, gas turbine fired with natural gas come along with emissions of CO2, NOx and CO. However, these disadvantages can be eliminated by using gas turbine with precombustion CO2 capture, separating carbon from the fuel by using fuel reforming process and feeding pure hydrogen as a fuel. Hydrogen fired gas turbines are used in two applications such as a gas turbine with pre-combustion CO2 capture and for renewable power plants where hydrogen is stored in case as a backup plan. Although the CO2 emissions are reduced in a hydrogen fired gas turbine with a pre-combustion CO2 capture, there are still several challenges such as high flame temperatures resulting in production of thermal NOx. This project suggests a method for application of hydrogen fired gas turbine, using exhaust gas recirculation to reduce flame temperature and thus reducing thermal NOx. A NOx emission model for a hydrogen-fired gas turbine was built from literature data and used to select the best operating conditions for the plant. In addition, the economic benefits of switching from natural gas to pure hydrogen are reported. For the techno-economic analysis, investment costs and operating costs were taken from the literature, and an economic model was developed. To provide sensitivity analysis for the techno-economic calculation, three cases were studied. Literature review was carried out on several journal articles and websites to gain understanding on hydrogen and natural gas fired gas turbines. Results showed that, in the current state, pure hydrogen has high delivery cost both in the US and Europe. While it’s easy to access natural gas at low cost, therefore in the current state gas turbine fired with natural gas are more profitable than hydrogen fired gas turbine. But, if targeted hydrogen prices are reached while fuel reforming process technology are developed in the coming future the hydrogen fired gas turbine will compete seriously with natural gas.

APA, Harvard, Vancouver, ISO, and other styles

37

Rahman, Khondokar Mizanur. "Determination of the potential energy contribution and green house gas mitigation of small and medium anaerobic digester systems in Bangladesh." Thesis, University of Brighton, 2011. https://research.brighton.ac.uk/en/studentTheses/efaddcb5-799a-4fb5-8bcd-d8a7736178db.

Full text

Abstract:

This research is to determine the anaerobic digestion (AD) potential and green house gas mitigation of small and medium anaerobic digester systems in Bangladesh which could provide energy for the country's need. This was determined for two common feedstocks: cattle dung and poultry litter. A third potential feedstock is also investigated as a novel and significant new source: waste rice straw used in cattle markets. These three feedstocks were chosen because between them, they cover a large fraction of scenarios in the country where AD could be used. All of the data needed to determine the energy parameters of these three representative AD facility types were collected (i.e. biogas yield, biogas composition, life cycle data). Highest biogas yield of 0.099 m3/kg feedstock and methane percentage 74.4% were found from cattle market rice straw feedstock. The relative potential contributions to energy were then calculated. Where no reliable secondary data was available, primary data was obtained, through site visits and surveys. In order to determine the potential distribution of these representative AD facility types across the country, a survey of 125 smallholdings/farms in one district was carried out. This showed that 70% of the potential energy from AD would come from the cattle feedstock (87% of energy for the cattle feedstock would come from domestic plants). The poultry feedstock contributes 16% of the potential energy (63% of energy from poultry feedstock would come from medium sized plant) and the rice straw from the cattle markets is 14% (53% large and 47% very large). The energy capacity is presented in terms of the potential development of small, medium and large AD facilities. The total potential for biogas energy from cattle farms, poultry farms and cattle market rice straw in Bangladesh is 240 x106 MJ (240 TJ). This energy is equivalent to 66.7 x 106 kWh which can meet the cooking energy requirements of 30 million people in Bangladesh. This study also contains a Life Cycle Assessment (LCA) and the result showed that the lifetime Global Warming Potential (GWP) of a 3.2 m3 cow dung fed AD plant is 130 tonnes of CO2 equivalent. Biogas as cooking fuel can reduce the GWP by 109 tonnes of CO2 equivalent. It means the reduction of GWP of a domestic AD plant is of 84% to 21 tonnes CO2 equivalent.

APA, Harvard, Vancouver, ISO, and other styles

38

Baumann, Lars. "Improved system models for building-integrated hybrid renewable energy systems with advanced storage : a combined experimental and simulation approach." Thesis, De Montfort University, 2015. http://hdl.handle.net/2086/11103.

Full text

Abstract:

The domestic sector will play an important role in the decarbonisation and decentralisation of the energy sector in the future. Installation numbers of building-integrated small-scale energy systems such as photovoltaics (PV), wind turbines and micro-combined heat and power (CHP) have significantly increased. However, the power output of PV and wind turbines is inherently linked to weather conditions; thus, the injected power into the public grid can be highly intermittent. With the increasing share of renewable energy at all voltage levels challenges arise in terms of power stability and quality. To overcome the volatility of such energy sources, storage technologies can be applied to temporarily decouple power generation from power consumption. Two emerging storage technologies which can be applied at residential level are hydrogen systems and vanadium-redox-flow-batteries (VRFB). In addition, the building-integrated energy sources and storage system can be combined to form a hybrid renewable energy system (HRES) to manage the energy flow more efficiently. The main focus of this thesis is to investigate the dynamic performance of two emerging energy storage technologies, a hydrogen loop composed of alkaline electrolyser, gas storage and proton exchange membrane (PEM) fuel cell, and a VRFB. In addition, the application of building-integrated HRES at customer level to increase the self-consumption of the onsite generated electricity and to lower the grid interaction of the building has been analysed. The first part deals with the development of a research test-bed known as the Hybrid Renewable Energy Park (HREP). The HREP is a residential-scale distributed energy system that comprises photovoltaic, wind turbine, CHP, lead acid batteries, PEM fuel cell, alkaline electrolyser and VRFB. In addition, it is equipped with programmable electronic loads to emulate different energy consumption patterns and a charging point for electric vehicles. Because of its modular structure different combinations of energy systems can be investigated and it can be easily extended. A unified communication channel based on the local operating network (LON) has been established to coordinate and control the HREP. Information from the energy systems is gathered with a temporal resolution of one second. Integration issues encountered during the integration process have been addressed. The second part presents an experimental methodology to assess the steady state and dynamic performance of the electrolyser, the fuel cell and the VRFB. Operational constrains such as minimum input/output power or start-up times were extracted from the experiments. The response of the energy systems to single and multiple dynamic events was analysed, too. The results show that there are temporal limits for each energy system, which affect its response to a sudden load change or the ability to follow a load profile. Obstacles arise in terms of temporal delays mainly caused by the distributed communication system and should be considered when operating or simulating a HRES at system level. The third part shows how improved system models of each component can be developed using the findings from the experiments. System models presented in the literature have the shortcoming that operational aspects are not adequately addressed. For example, it is commonly assumed that energy systems at system level can respond to load variations almost instantaneously. Thus, component models were developed in an integrated manner to combine theoretical and operational aspects. A generic model layout was defined containing several subsystems, which enables an easy implementation into an overall simulation model in MATLAB®/Simulink®. Experimental methods were explained to extract the new parameters of the semi-empirical models and discrete operational aspects were modelled using Stateflow®, a graphical tool to formulate statechart diagrams. All system models were validated using measured data from the experimental analysis. The results show a low mean-absolute-percentage-error (<3%). Furthermore, an advanced energy management strategy has been developed to coordinate and to control the energy systems by combining three mechanisms; statechart diagrams, double exponential smoothing and frequency decoupling. The last part deals with the evaluation, operation and control of HRES in the light of the improved system models and the energy management strategy. Various simulated case studies were defined to assess a building-integrated HRES on an annual basis. Results show that the overall performance of the hydrogen loop can be improved by limiting the operational window and by reducing the dynamic operation. The capability to capture the waste heat from the electrolyser to supply hot water to the residence as a means of increasing the overall system efficiency was also determined. Finally, the energy management strategy was demonstrated by real-time experiments with the HREP and the dynamic performance of the combined operation has been evaluated. The presented results of the detailed experimental study to characterise the hydrogen loop and the VRFB as well as the developed system models revealed valuable information about their dynamic operation at system level. These findings have relevance to the future application and for simulation studies of building-integrated HRES. There are still integration aspects which need to be addressed in the future to overcome the proprietary problem of the control systems. The innovations in the HREP provide an advanced platform for future investigations such as electric-vehicles as decentralised mobile storage and the development of more advanced control approaches.

APA, Harvard, Vancouver, ISO, and other styles

39

Yu, Fu-Chen. "Reactivation Mechanism Studies on Calcium-Based Sorbents and its Applications for Clean Fossil Energy Conversion Systems." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1298957301.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Johnson, Matthew. "Sustainable design analysis of waterjet cutting through exergy/energy and LCA analysis." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003231.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Lundquist, Philip. "Operation strategies of using energy storage for improving cost efficiency of wind farms. : Examining emergency power supply and support services." Thesis, Uppsala universitet, Elektricitetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-447078.

Full text

Abstract:

With the increase in the world energy demand and environmental incentives, renewable energy sources (RES) need to determine their place as some of the primary power sources in future power systems. However, due to uncertain energy production, renewable energy sources cause unbalance in the power system due to the unsynchronized supply and electricity demand. The intermittent power production causes undesired power fluctuation, affecting the power quality and reliability of the power source. Energy storage is one solution that is debated to increase the reliability of renewable energy production. This thesis aims to model and simulate hybrid energy storage system (HESS), constructed of hydrogen and ultracapacitor energy storage, to investigate different operation strategies for everyday use and crises. The two different energy storage technologies complement each other, where hydrogen fuel cells can produce power for long periods of time while the ultracapacitor can quickly maintain the balance of production and consumption of electricity for a short instance. The HESS showed promising results for emergency power supply and supported service operation strategies. In case of a power shortage, the HESS could cover for the disconnected production. The ultracapacitor proved to be a suitable component due to its ability to support the shortcomings of a hydrogen energy storage system. Moreover, the HESS could meet the requirements to deliver support services. However, further studies have to be done to investigate how the HESS can deliver multiple support services to increase profit and help maintain the power system's balance and security.

APA, Harvard, Vancouver, ISO, and other styles

42

Hoeppner, Jeffrey Wayne. "The effects of legume green manures, perennial forages, and cover crops on non-renewable energy use in western Canadian cropping systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62754.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Weigel, Brent Anthony. "Development of a commercial building/site evaluation framework for minimizing energy consumption and greenhouse gas emissions of transportation and building systems." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44735.

Full text

Abstract:

In urbanized areas, building and transportation systems generally comprise the majority of greenhouse gas (GHG) emissions and energy consumption. Realization of global environmental sustainability depends upon efficiency improvements of building and transportation systems in the built environment. The selection of efficient buildings and locations can help to improve the efficient utilization of transportation and building systems. Green building design and rating frameworks provide some guidance and incentive for the development of more efficient building and transportation systems. However, current frameworks are based primarily on prescriptive, component standards, rather than performance-based, whole-building evaluations. This research develops a commercial building/site evaluation framework for the minimization of GHG emissions and energy consumption of transportation and building systems through building/site selection. The framework examines, under uncertainty, multiple dimensions of building/site operation efficiencies: transportation access to/from a building site; heating, ventilation, air conditioning, and domestic hot water; interior and exterior lighting; occupant conveyances; and energy supply. With respect to transportation systems, the framework leverages regional travel demand model data to estimate the activity associated with home-based work and non-home-based work trips. A Monte Carlo simulation approach is used to quantify the dispersion in the estimated trip distances, travel times, and mode choice. The travel activity estimates are linked with a variety of existing calculation resources for quantifying energy consumption and GHG emissions. With respect to building systems, the framework utilizes a building energy simulation approach to estimate energy consumption and GHG emissions. The building system calculation procedures include a sensitivity analysis and Monte Carlo analysis to account for the impacts of input parameter uncertainty on estimated building performance. The framework incorporates a life cycle approach to performance evaluation, thereby incorporating functional units of building/site performance (e.g energy use intensity). The evaluation framework is applied to four case studies of commercial office development in the Atlanta, GA metropolitan region that represent a potential range of building/site alternatives for a 100-employee firm in an urbanized area. The research results indicate that whole-building energy and GHG emissions are sensitive to building/site location, and that site-related transportation is the major determinant of performance. The framework and findings may be used to support the development of quantitative performance evaluations for building/site selection in green building rating systems and other efficiency incentive programs designed to encourage more efficient utilization and development of the built environment.

APA, Harvard, Vancouver, ISO, and other styles

44

von, Hepperger Florian. "Implementation of water electrolysis in Växjö´s combined heat and power plant and the use of excess heat : A techno-economic analysis." Thesis, Linnéuniversitetet, Institutionen för byggd miljö och energiteknik (BET), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105276.

Full text

Abstract:

Renewable energies are fluctuating and the bigger its share on the Swedish energy market, the more fluctuating are the prices. Therefore, CHP plant operators as VEAB in Växjö, are more and more struggling to be competitive. There is, hence, a need of alternative options for the use of produced electricity, rather than being dependent on such a volatile and unclear market. Hydrogen production through water electrolysis could therefore be an alternative to be decoupled from the electricity business and instead being part of a promising, future hydrogen economy. Since state-of-the-art electrolysers have efficiencies between 51% and 75%, it was assessed that some of the efficiency losses could be recuperated by implementing the excess heat in an existing District heating (DH) grid. Calculations of the base scenario electrolyser with a power input of 870 kW showed, that an increase of the overall temperatures of the returning mass flow of the DH grid from 0,05°C to 0,23°C should be achievable. The economic analysis showed, that for this size of hydrogen production unit, the minimum hydrogen selling price (MHSP) would be 6,64 €/kg, which is not competitive on today’s market. However, the sensitivity analysis showed, that by a decreased investment cost, lower electricity prices and especially by scaling up the base scenario, the MHSP could be lowered significantly. Assuming a reduction of investment costs of 20% and scaling up the electrolyser by 1000% to 8700 kW, the MHSP resulted in 1,9 €/kg, a competitive price on the market. This study revealed that hydrogen production could be part of the future business model of CHP plant operators and provides a guideline on the feasibility of such a project.

APA, Harvard, Vancouver, ISO, and other styles

45

Almatouq, Abdullah. "Study of the parameters for optimisation of the design and performance of bio-electrochemical systems for energy/hydrogen generation and resource recovery." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/100405/.

Full text

Abstract:

This study focused on the exploration, assessment and experimental investigation of bio-electrochemical systems (BES) for concurrent phosphorus (P) recovery and energy generation/hydrogen (H2) production. The main aim was to study and understand the parameters for optimisation of the design and the performance of BESs for concurrent phosphorus recovery and energy generation/hydrogen production. In total, four dual chamber bio-electrochemical systems (Microbial Fuel Cells (MFCs) and Microbial Electrolysis Cells (MECs)) were used to investigate the impacts of key design and operational conditions on BES performance. P was precipitated successfully as struvite in both MFCs and MECs. The MFCs and MECs achieved a maximum P precipitation efficiency of 90% and 95% with a maximum columbic efficiency of 10% and 51% respectively. The MFCs and MECs achieved an average of 80 % and 70 % COD removal efficiency respectively, which confirms the ability of these systems to be used in wastewater treatment. Deterioration in both reactors occurred due to P precipitation on the cathode surface and the membrane. The three operational parameters (influent COD, cathode aeration flow rate, and external resistance) were found to have significant impacts on MFC performance and P recovery. In addition, applied voltage and influent COD had significant effects on MEC performance and P recovery. Results were supported through statistical analysis and optimisation modelling using full factorial design, central composite design, and response surface methodology. Generally, results have shown that MFCs and MECs have the potential to concurrently recover P, treat wastewater, and generate electricity/produce H2. Further research is needed to enhance the performance of MFCs for energy generation and MECs for H2 production in addition to P recovery and minimising scaling on electrodes. The results of this study increase the understanding of P recovery mechanisms in MFCs and MECs and can contribute to future BES research. Moreover, the results will help in selecting the optimum operational parameters of BESs depending on the applications and process requirements. Applying BESs in wastewater treatment plants will reduce energy consumption and, at the same time, find an alternative source of P.

APA, Harvard, Vancouver, ISO, and other styles

46

Torstensson, Johan, and Jon Gezelius. "Waste-to-Energy in Kutai Kartanegara, Indonesia : A Pre-feasibility study on suitable Waste-to-Energy techniques in the Kutai Kartanegara region." Thesis, Energi och teknik, SLU, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-269607.

Full text

Abstract:

The thesis outlined in this report is a pre-feasibility study of the potential to use waste-to-energy technology in the region Kutai Kartanegara, Borneo, Indonesia. The project is a collaboration between the Kutai Kartanegara government, Uppsala University, the Swedish University of Agricultural sciences and the technology consulttancy Sweco. The current waste management system in Kutai Kartanegara consists of landfills in the cities and open burnings and dumping in the lesser developed sub-districts. This is a growing problem both environmentally and logistically. The electrification in the sub-districts is sometimes as low as 17 % and access to electricity is often limited to a couple of hours per day. The current electricity production in the region is mainly from fossil fuels. Data was collected during a two month long field study in Tenggarong, the capital of Kutai Kartanegara. From the collected data, various waste-to-energy systems and collection areas were simulated in Matlab. Results from the simulations show that a system using both a waste incineration and biogas plant would be the best solution for the region. The chosen system is designed to handle a total of 250,000 tons of waste annually, collected from Tenggarong and neighbouring districts. The system will provide between 155 and 200 GWh electricity and between 207 and 314 GWh of excess heat energy annually. Some of this is used in a district heating system with an absorption-cooling machine. The system investment cost is around 42.5 MUSD and it is expected to generate an annual profit of 16 MUSD. The recommended solution will decrease the emissions of CO2-equivalents compared to the current waste system and fossil electricity production with 50%. The results in the study clearly show that there are both economic and environmental potential for waste-to-energy technologies in the region. But the waste management and infrastructure has to be improved to be able to utilize these technologies. By implementing waste-to-energy technologies, the supplied waste can be seen as a resource instead of a problem. This would give incentives for further actions and investments regarding waste management.

APA, Harvard, Vancouver, ISO, and other styles

47

Ekström, Adrian, and Karl Johan Tegnér. "Green National Innovative Capacity : An empirical study of the determinants of patenting in technologies related to renewable energy sources." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264092.

Full text

Abstract:

Climate change constitutes a major threat to our planet. Finding and developing new technologies that can utilize renewable sources of energy is an essential component in combating this threat. The concerns are global, and today there is large variation in innovation intensity across advanced countries. Motivated by these differences, this thesis provides an empirical investigation of the determinants of country-level production of patents related to renewable energy generation. The investigation examines the impact of public environmental policy by assessing the effect of policy stringency and environmental taxes on renewable patents. Green innovative capacity is not separated from general innovative capacity. Drawing from the concept of national innovation system we therefore identify country-specific factors of innovation and examine to what extent they can be translated to the domain of environmental technology. We construct a panel of 22 OECD countries over the years 1994-2015 and analyze how governmental R&D expenditures, how different macroeconomic and institutional factors, as well as how environmental policy stimulate innovative activities. We analyze these factors using regression analysis and we use two count data models, namely the Poisson model and the Negative Binomial model. Our findings suggest that public policy is important for inducing innovation, both by deciding the level of R&D resources available to the economy and the level of environmental taxes. Furthermore, our thesis provides evidence that certain determining factors of general innovative performance also affect countries’ innovative capacity in green technologies. Klimatförändringarna utgör idag ett allvarligt hot mot vår planet. Vår förmåga att ta fram ny teknologi, inte minst inom förnyelsebar energi, har pekats ut som en avgörande faktor för att vi ska kunna möta klimatkrisens utmaningar. Idag kan vi observera stora skillnader mellan länder när det kommer till deras förmåga att introducera och utveckla teknik kopplad till förnybara källor. För att förstå vilka faktorer som avgör ett lands benägenhet att generera ny teknologi inom detta område genomför vi i denna uppsats en empirisk undersökning med fokus på patentstatistik. Vi undersöker både effekten av stringens samt om miljöskatter kan användas för att stimulera mer förnybar innovation. Då länders innovativa förmåga inom grön teknologi är svår att separera och är starkt kopplad till dess generella innovativa förmåga utgår vår studie från teorin om nationella innovationssystem. Genom att använda det ramverket identifierar vi flera olika landspecifika faktorer som antas påverkar länders benägenhet att patentera teknik och vi utvärderar således teorins relevans inom området för förnyelsebar energi. Denna studie bygger på paneldata från OECD-länder mellan åren 1994 - 2015, data som sedermera används för att analysera hur statliga insatser kopplade till FoU, hur olika institutionella och makroekonomiska faktorer, samt hur miljöpolicy påverkar innovation inom grön teknologi. Våra resultat visar att policy, både i form av satsningar på FoU samt att miljöpolitiska åtgärder, spelar en betydande roll för att främja innovation inom förnyelsebar energi. Vidare finner vi i denna uppsats att de faktorer som påverkar ett lands generella innovativa förmåga också till en viss del påverkar dess förmåga att ta fram och patentera ny teknik kopplad till förnyelsebara energikällor.

APA, Harvard, Vancouver, ISO, and other styles

48

Cai, Zhichang. "From energy efficiency to integrated sustainable urbanism in residential development in China." Licentiate thesis, KTH, Industriell ekologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25233.

Full text

Abstract:

China has adopted Sustainable Development as a national strategy for all industries. In civil construction sector, sustainability is regarded as the development of Green Building in China. Since 2000, China has introduced a series of policies and laws to promote Green Building. Green Building was defined as buildings that are “energy-efficient, land-efficient, water-efficient, and material-efficient” and emit “minimal pollution” in during its entire life cycle, and meets a specified standard for indoor environment at the same time. However, energy efficiency is the central issue of current Green Building development in China, while issues of resources and pollution are neglected, which is partly due to China’s energy structure. Social and economic aspects are also always ignored. The main aim of this thesis is to map pathways towards more comprehensive frameworks for how residential areas in China could be constructed in a more sustainable way in hot –summer and cold-winter area. Case study was the main method used to examine the specifications of Green Residential Building in China. This paper offers a general overview of the current green trend in China and presents a specific analysis on three cases to search for the proper approach for China’s unique situation by three specific cases representing three types of Green Building: Modern Vernacular Architecture, Eco-office and Mass-housing, according to their features in scale, location and function. This paper then presents a specific integrated sustainability analysis of the Landsea Housing Project in Nanjing, a hot-summer/cold-winter zone. Hammarby Sjöstad, a cutting edge project in Stockholm, is also discussed as a reference area from which experiences can be drawn for China. The aim was to improve the framework for construction of residential buildings in China in a more sustainable way, from energy efficiency to integrated sustainability. The paper also discusses the relationship between the economic growth and energy consumption in the fast-growing situation, presents several scenarios depicting energy and comfort and makes suggestions for China. The roles of government, developers and residents are also addressed. The paper argues that an adaptive and holistic approach, which must be expanded from both spatial scale and temporal span, should be established for the Green Residential Building development in China, as an effective way to meet the sustainability goal. QC 20101013

APA, Harvard, Vancouver, ISO, and other styles

49

Topriska, Evangelia Vasiliki. "Experimental and computational study of a solar powered hydrogen production system for domestic cooking applications in developing economies." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12824.

Full text

Abstract:

In many developing economies, a high percentage of domestic energy demand is for cooking based on fossil and biomass fuels. Their use has serious health consequences affecting almost 3 billion people. Cleaner cooking systems have been promoted in these countries such as solar cooking and smokeless stoves with varying degrees of success. In parallel, solar electrolytic hydrogen systems have been developed and increasingly used during the last 25 years for electricity, heat and automobile fueling applications. This study has developed and tested experimentally in the laboratory a solar hydrogen plant numerical model suitable for small communities, to generate and store cooking fuel. The numerical model was developed in TRNSYS and consists of PV panels supplying a PEM electrolyser of 63.6% measured stack efficiency and hydrogen storage in metal hydride cylinders for household distribution. The model includes novel components for the operation of the PEM electrolyser, its controls and the metal hydride storage, developed based on data of hydrogen generation, stack temperature and energy use from a purpose constructed small-scale experimental rig. The model was validated by a second set of experiments that confirmed the accurate prediction of hydrogen generation and storage rates under direct power supply from PV panels. Based on the validated model, large-scale case studies for communities of 20 houses were developed. The system was sized to generate enough hydrogen to provide for typical domestic cooking demand for three case-studies; Jamaica, Ghana and Indonesia. The daily cooking demands were calculated to be 2.5kWh/day for Ghana, 1.98kWh/day for Jamaica and 2kWh/day for Indonesia using data mining and a specific quantitative survey for Ghana. The suitability of weather data used in the model was evaluated through Finkelstein Schafer statistics based on composite and recent weather data and by comparing simulation results. A difference of 0.9% indicated that the composite data can be confidently used. Simulations results indicate that a direct connection system to the PV plant rather than using a battery is the optimal design option based on increased efficiency and associated costs. They also show that on average 10tonnes of CO2/year/household can be saved by replacing biomass fuel with hydrogen. The potential of total savings in the three case-study countries is shown in the form of novel solar hydrogen potential maps. The results of this study are a contribution towards better understanding the use of hydrogen systems and enhancing their role in renewable energy policy.

APA, Harvard, Vancouver, ISO, and other styles

50

Reissner, Alexander [Verfasser], Martin [Akademischer Betreuer] Tajmar, and Andreas [Gutachter] Werner. "Metal Hydrides as Enabling Technology for the use of Hydrogen-Based Energy Storage Systems on Telecommunication Satellites / Alexander Reissner ; Gutachter: Andreas Werner ; Betreuer: Martin Tajmar." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/1140735268/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Green hydrogen energy systems'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles