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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Data-driven modelling for demand response from large consumer energy assets

Krishnadas, Gautham January 2018 (has links)
Demand response (DR) is one of the integral mechanisms of today's smart grids. It enables consumer energy assets such as flexible loads, standby generators and storage systems to add value to the grid by providing cost-effective flexibility. With increasing renewable generation and impending electric vehicle deployment, there is a critical need for large volumes of reliable and responsive flexibility through DR. This poses a new challenge for the electricity sector. Smart grid development has resulted in the availability of large amounts of data from different physical segments of the grid such as generation, transmission, distribution and consumption. For instance, smart meter data carrying valuable information is increasingly available from the consumers. Parallel to this, the domain of data analytics and machine learning (ML) is making immense progress. Data-driven modelling based on ML algorithms offers new opportunities to utilise the smart grid data and address the DR challenge. The thesis demonstrates the use of data-driven models for enhancing DR from large consumers such as commercial and industrial (C&I) buildings. A reliable, computationally efficient, cost-effective and deployable data-driven model is developed for large consumer building load estimation. The selection of data pre-processing and model development methods are guided by these design criteria. Based on this model, DR operational tasks such as capacity scheduling, performance evaluation and reliable operation are demonstrated for consumer energy assets such as flexible loads, standby generators and storage systems. Case studies are designed based on the frameworks of ongoing DR programs in different electricity markets. In these contexts, data-driven modelling shows substantial improvement over the conventional models and promises more automation in DR operations. The thesis also conceptualises an emissions-based DR program based on emissions intensity data and consumer load flexibility to demonstrate the use of smart grid data in encouraging renewable energy consumption. Going forward, the thesis advocates data-informed thinking for utilising smart grid data towards solving problems faced by the electricity sector.
212

Connecting the dots : a systemic approach to evaluating potential constraints to renewable electricity technology deployment to 2020 and beyond in the United Kingdom

Wood, Geoffrey Craig January 2013 (has links)
The UK government has committed to challenging climate change and renewable energy obligations to 2020 and beyond. The renewable electricity sector remains a key focus in meeting these targets, given the critical need to decarbonise the power sector in the longer term. This has led to an ambitious renewable electricity sectoral target of 30 percent of total electricity generation from renewable sources (RES-E) by 2020, corresponding to a deployment target of 35-40GW of installed capacity. In 2011, RES-E deployment stood at 12.3GW, resulting in the UK requiring 23-28GW of additional renewable electricity technology (RET) deployment in eight years. This requires a substantial amount of new RET capacity be adopted, the majority anticipated to come from a four large-scale (>5MW) technologies (onshore and offshore wind, biomass conversion and dedicated biomass). However, large-scale renewable deployment has consistently under-performed against previous targets and other policy objectives. There are a number of failures that historically and currently act as constraints to RET deployment. This thesis categories those constraints as either internal or external failures. Internal failures are due to the design of the subsidy mechanism used to promote renewable deployment (type of mechanism, how it operates, revenue risk, investment (lender) risk, subsidy support levels and mechanism complexity). External failures are those constraints out-with the direct control of the mechanism (planning, network, public participation and engagement and policy risk). These constraints need to be addressed. This thesis has carried out an evaluation of the current UK approach to large-scale RET deployment to 2020 and beyond by adopting a systemic framework approach to determine whether or not the UK will be successful in addressing the potential constraints – the internal and external failures – to deployment. The systemic approach is based on three key criteria regarding the potential constraints: a comprehensive set of constraints, analysed in-depth and taking into account the interaction of the constraints in a systemic fashion. In contrast, the government approach to dealing with these potential constraints has typically focused on failures in isolation; also government commissioned modelling and existing research does not take into account all of the internal and external failures and/or examine them in-depth. Critically, no research has analysed the systemic interactions. With this approach, this research aims to fill the gap in extant knowledge and analysis due to the absence of existing research meeting the key criteria. This thesis was carried out by a textual analysis of key policy documents and legislation that form the basis of the UK government’s current approach to addressing the barriers to RET deployment. The method of inquiry utilised here is that of the qualitative research approach. The results show that there are significant systemic interactions between the internal and external failures (internal>internal; external>external; and internal to external and vice versa). There are also a number of feedbacks, specifically between grid>planning and public participation and engagement>planning. This creates systemic imbalances and unresolved tensions between the constraints. Importantly, the systemic interactions impact disproportionately on the key RETs, with a particular emphasis on onshore and offshore wind. By not addressing potential constraints from a systemic perspective, the current UK approach discriminates in favour of a system highly dependent on large-scale developments, of a few select RETs by a limited number of developers of a particular type (typically ex-utility, large-scale). This limits the focus on social and behavioural issues, particularly in terms of participation and engagement in ownership, decision-making and reducing the role of small-scale, independent and community group participation. In conclusion, under the current approach, decisions will be made on a separate ad-hoc basis leading to continual reform and adjustment with less clarity of where the risks lie. Increasing deployment year-by-year will only accumulate and intensify the potential constraints with limited options to address this. Effectively, government can only buy or control its way out of the constraints. In contrast, a systemic approach offers policy makers a way out of this. By providing an overview of the system and identification of systemic interactions in an early and novel way, this approach offers the opportunity for pragmatic decision-making at the systemic level leading to more predictable routes to solving problems via focused reforms, thus mitigating risks to a greater extent and redefining the system in a more optimal and resilient way. In other words, it allows government to connect the dots in addressing potential constraints to deployment.
213

Caracterização e avaliação do potencial de aplicação bioindustrial da bacteriofauna intestinal de Armitermes euamignathus Silvestri, 1901 (Isoptera: Termitidae) e Coptotermes gestroi (Wasmann, 1896) (Isoptera: Rhinotermi / Characterization and potential for bioindustrial application of the gut bacteriofauna of Armitermes euamignathus Silvestri, 1901 (Isoptera: Termitidae) and Coptotermes gestroi (Wasmann, 1896) (Isoptera: Rhinotermitidae)

Peruchi, Aline 04 December 2013 (has links)
Microrganismos simbiontes são essenciais para a exploração de dietas de baixo valor nutricional, o desenvolvimento, crescimento e a reprodução de seus hospedeiros. Insetos que se alimentam de dieta rica em materiais celulósicos, como é o caso de cupins, apresentam protozoários e/ou bactérias associadas ao trato digestivo que auxiliam na quebra do polímero de celulose e na fixação de nitrogênio. A celulose e a hemicelulose são polímeros estruturais formados por unidades de glicose, sendo a hidrólise desses polímeros de grande interesse industrial para a produção de etanol. O modo mais eficiente de hidrolisar a celulose é pelo uso de enzimas, as celulases. Os cupins apresentam grande eficiência na digestão de celulose e hemicelulose, sendo que a compreensão do processo de digestão de celulose por esses insetos pode facilitar o desenvolvimento de tecnologia mais eficiente para a quebra desse polímero. Assim, este trabalho buscou i) isolar, identificar e caracterizar microrganismos associados ao trato digestivo dos cupins Armitermes euamignathus (Isoptera: Termitidae) e Coptotermes gestroi (Isoptera: Rhinotermitidae); ii) verificar o potencial da microbiota na degradação dos principais componentes da lignocelulose (celulose, xilana e pectina); iii) caracterizar o potencial hidrolítico e determinar as condições ótimas de hidrólise (pH e temperatura das diferentes enzimas produzidas). A análise da microbiota cultivável levou à identificação de 14 filotipos para A. euamignathus e de 11 para C. gestroi, distribuídos nos quatro principais filos, Proteobacteria, Firmicutes, Bacteroidetes e Actinobacteria. A caracterização da microbiota não-cultivável levou à identificação de 17 filotipos em operários e três em soldados de A. euamignathus, enquanto que em C. gestroi foi possível identificar seis filotipos em operários e oito em soldados. O filo Firmicutes foi o mais abundante em A. euamignathus, enquanto Proteobacteria predominou em C. gestroi. O isolamento de bactérias em meio seletivo para degradação de celulose, xilana ou pectina levou à seleção de oito filotipos para A. euamignathus e cinco para C. gestroi. Extratos brutos obtidos do cultivo dessas bactérias apresentaram atividade de hidrólise de pectina e xilana, mas não celulose. Ensaios para otimização das reações de degradação indicaram a presença de enzimas que atuam em diferentes faixas de pH ótimo. Assim, a microbiota associada aos cupins estudados foi bastante diversa, apresentando ainda diferenças entre as diferentes castas desses insetos. Essa microbiota também atua em parte do processo de degradação da celulose, demonstrando o potencial que bactérias associadas ao intestino de cupins podem apresentar para a identificação de enzimas digestivas que possam ser utilizadas no processamento da celulose. / Symbionts are essential for insect hosts as they enhance the nutritional value of their host diets and support host development, growth and reproduction. Insects that feed on diets rich in cellulose, such as termites, exhibit protozoa and/or bacteria within their digestive tract that aid in breaking the cellulose and in nitrogen fixation. Cellulose and hemicellulose are polymers formed by units of glucose, and the hydrolysis of these polymers is of great industrial interest for the production of ethanol. Cellulases are the most efficient enzymes to break cellulose. Termites have a huge capacity to digest cellulose and hemicellulose; thefore, understanding the process by which they digest cellulose may allow the development of more suitable technologies devoted to the industrial utilization of cellulose. This work aimed to i) isolate, identify and characterize microorganisms associated with the digestive tract of Armitermes euamignathus (Isoptera: Termitidae) and Coptotermes gestroi (Isoptera: Rhinotermitidae), ii) investigate the potential of symbionts in the degradation of the main components of lignocellulose (cellulose, xylan and pectin); iii) characterize the hydrolytic potential and determine the optimum hydrolysis conditions (pH and temperature) for the different enzymes produced. The analysis of culturable microorganisms led to the identification of 14 phylotypes for A. euamignathus and 11 for C. gestroi, which were distributed in four Phyla, Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria. The characterization of the non-culturable microbiota led to the identification of 17 phylotypes in workers and three in soldiers of A. euamignathus, while six phylotypes were identified in workers and eight in soldiers of C. gestroi. Firmicutes was the most abundant in A. euamignathus, while Proteobacteria predominated in C. gestroi. The isolation of bacteria in selective medium to degrade cellulose, xylan or pectin led to the selection of eight phylotypes from A. euamignathus and five from C. gestroi. Crude extracts obtained from the cultivation of these bacteria showed hydrolytic activity towards to xylan and pectin, but not cellulose. Assays for optimization of enzymatic reaction indicated the presence of enzymes that act at different pH ranges great. As a conclusion, symbiont diversity was quite different between the termites species and in between the castes of these species. But the microbiota isolated also acts in the degradation of cellulose, demonstrating the potential for the gut-associated bacteria of termites may present for the identification of digestive enzymes which can be used in the processing of cellulose.
214

Is India's Push for Renewables a Shove to its Impoverished Communities?

Mehra, Amaani 01 January 2019 (has links)
India has ambitious targets to develop extensive renewable energy infrastructure by 2022. These targets are driven by the country’s pressing environmental and demographic concerns. While the development of such infrastructure can have many benefits, the costs of are often disproportionately borne by some of the most impoverished groups due to land acquisition and displacement. Land acquisition often occurs in rural areas, where the majority of the population are farmers or tribal groups. While there are laws to protect the rights of these groups, the effectiveness of these laws is often undermined by state governments that prioritize investment. Looking at the development of solar, wind, and small hydropower, the various impacts on rural communities are evident. Without adequate compensation for the loss of land and the suffering caused by displacement, these groups can often be left worse off than before. Government support needs to be carried out in a way that encourages maximum deployment, while also enforcing regulations that protect the rights of rural communities.
215

Small-Scale Solar Central Receiver System Design and Analysis

Murray, Daniel 01 June 2012 (has links)
This thesis develops an analytical model of a small-scale solar central receiver power plant located at the California Polytechnic State University in San Luis Obispo, California at 35.28° N, 120.66° W. The model is used to analyze typical energy output at any time during the year. The power plant is designed to produce an output of 100 kW electrical power, and is supplemented by the combustion of natural gas. Methodologies for determining the proper size and layout of heliostats, optimal tower height, receiver size, and turbine engine selection are developed. In this specific design, solar shares of up to 73.2% and an annual average of 44% are possible through the use of a gas-solar hybrid microturbine engine. Larger solar shares are not possible due to the limited size of land (about 0.5 acres used for this project) which limits the number of possible heliostat installations.
216

Distributed Generation: Issues Concerning a Changing Power Grid Paradigm

Therien, Scott G.M. 01 June 2010 (has links)
Distributed generation is becoming increasingly prevalent on power grids around the world. Conventional designs and grid operations are not always sufficient for handling the implementation of distributed generation units; the new generation may result in undesirable operating conditions, or system failure. This paper investigates the primary issues involved with the implementation of distributed generation and maintaining the integrity of the power grid. The issues addressed include power flow, system protections, voltage regulation, intermittency, harmonics, and islanding. A case study is also presented to illustrate how these issues can be addressed when designing distributed generation installation on an existent distribution system. The case study design is performed on the campus distribution system of California Polytechnic State University, San Luis Obispo, with the design goal of implementing renewable energy sources to make the campus a net zero energy consumer.
217

Technology Assessment Model of Developing Geothermal Energy Resources for Supporting Electrical System: the Case for Oregon

Alshareef, Ahmed Shehab 03 April 2017 (has links)
The demand for energy is increasing worldwide. All applications contributed to increase the demand of all energy industry, and therefore the effect on the environment and the rise in pollution increased significantly. This is considered a large problem, and researchers focused their research on renewable energy for reducing the cost of energy in the future. Geothermal energy has significant impact as a source of electricity generation since it will not harm the environment. There are more than twenty countries that benefit from geothermal plants, which generate more than 6000 megawatts .Three alternatives of geothermal energy technology (GHP, Direct use of Geothermal Heat, and Geothermal Electricity) can be used for supporting electrical systems in Oregon. At the same time, the success of using the geothermal energy alternatives in Oregon relies on different goals for achieving the best geothermal development. Oregon has been ranked third in the potential use of geothermal energy after Nevada and California. The objective from the research study was to develop an assessment model framework that can be used for supporting cost effective renewable energy in Oregon by the development of geothermal energy sources. This research of study was done by using the Hierarchical Decision Model (HDM) and consisted of four levels: Mission, objectives, goals, and alternative. Criteria used in this research study are based on five objectives to know what are the most important factors in the decision-making process. These objectives are: social, environmental, economical, technical, and political. The decision model connected objectives, goals, and alternative for obtaining the accurate decision. HDM used for this purpose to analyze the result of data collected from experts. Seven experts who had experience in the geothermal field participated in this research study, and they gave their judgment in the questionnaire survey link by using pair-wise comparison method. The outcome analysis of the results showed that in terms of objectives that Minimizing Environmental Impact was rated at the highest value at 0.26 with respect to the mission. Within the category of Minimizing Environmental Impact, Seismic Activity and GHG Emissions had higher values. The results show that "Geothermal Electricity," with a rating of 43%, was ranked as the most important alternative with respect to mission, objectives, and goals. "Direct Use of Geothermal Heat" was ranked as the second most important alternative with 31%. The results of this research study were discussed with the experts to get their feedback, and learn from them what requirements are necessary for improvement in the geotechnical energy sector for future research. The experts agreed that this methodology is a good approach to help reach the right decision since this methodology (HDM) divides the problem into small sets, which will make the decision process easier.
218

Fabrication of CIGS Absorber Layers Using a Two-Step Process for Thin Film Solar Cell Applications

Sankaranarayanan, Harish 14 June 2004 (has links)
Copper Indium Gallium DiSelenide absorber layers are fabricated using a two step manufacturing-friendly process. The first step involves the sequential deposition of Copper and Gallium and codeposition of Indium and Selenium, not necessarily in that order, at 275o C. This is followed by the second stage, where the substrate is annealed in the presence of Selenium and a thin layer of Copper is deposited to neutralize the excess Indium and Gallium on the surface to form the Copper Indium Gallium diSelenide absorber layer. Elimination of the need for high degree of control and elimination of toxic gases like hydrogen selenide aid in the easy scalability of this process to industry. The performance of CuInGaSe2/CdS/ZnO solar cells thus fabricated was characterized using techniques such as I-V, C-V, Spectral Response and EDS/SEM. Cells with open circuit voltages of 450-475 mV, short circuit current densities of 30-40 mA/cm², fill factors of 60-68% and efficiencies of 8-12% were routinely fabricated. Gallium in small amounts seems to improve the open circuit voltages by 50-100 mV without significantly affecting the short circuit currents and the band gap in Type I precursors. Gallium also improves the adhesion of the CIS layer to the molybdenum back contact. Efforts are also being aimed at improving the short circuit current densities in our high bandgap devices. It is believed that improperly bonded Ga is hurting the electronic properties of the CIGS films. A part of this work involves the reduction of the detrimental effect of Ga on the Jsc's by modifying the base process, so as to improve the homogeneity of the film. The modifications include lowering the Ga level as well as fine-tuning the annealing step. Ar annealing of the samples has also been incorporated. The short circuit current densities have been improved significantly by the above mentioned modifications. At present, the best Jsc's are in the 33-35 mA/cm² range. The Voc's have also been improved by splitting the Ga into two layers and replacing the top Cu layer by a Ga layer. Light soaking studies of the absorber have also been carried out. The baseline Type I process has also been adapted to a new load-locked in-line evaporator system. Device performance dependence on Ga and In thickness as well as the top selenization temperature has been determined in this research. The effect of moisture on the quality of the films has been studied. Bandgap variations due to the presence/absence of Se during the Cu deposition has been investigated. The impact of substrate cleaning/Moly deposition conditions on the device performance has been explored. Insitu Ar annealing studies of CIGS absorbers have been carried out. Alternate buffer layers have been pursued. Devices with Voc's as high as 480 mV, Jsc's as high as 40.7 mA/cm² and fill factors of 66% have been fabricated.
219

Analyse des perspectives à long terme du système énergétique du Québec : le potentiel renouvable

Connord-Lajambe, Hélène January 1986 (has links)
No description available.
220

A Case Study of Solar Powered  Cellular Base Stations

PANDE, GEETHA January 2009 (has links)
<p>Green power, environment protection and emission reduction are key factors nowadays in the telecom industry. Balancing of these modes while reducing the capital and operational costs are of prime importance.  Cost efficient and reliable supply of electricity for mobile phone base stations must be ensured while expanding the mobile phone network. In this context, solar energy, using sophisticated photovoltaic cell technology, is considered to be playing very important role.</p><p>Currently, companies such as ABI research, Flexenclosure AB, etc believe that the solar powered cellular base stations are capable of transforming the telecom industry into one of the greenest in the world. Hence, lot of research is in progress across the globe to use solar power in telecom industry.</p><p>In this thesis work, the significance of solar power as renewable energy source for cellular base stations is reviewed. Moreover, simulation software called PVSYST4.37 is used not only to obtain an estimate of the cost of generation of solar power for cellular base stations but also to obtain the system parameters such as the number of modules, batteries and inverters needed for designing the solar powered cellular base stations. The simulations were carried out for the Grid-Connected and the Stand-Alone solar power systems by considering the cases of New Delhi, India and Stockholm, Sweden.</p><p>The PVSYST4.37 simulation results shows that the power generation costs for the grid connected solar powered system is less compare to standalone solar powered system both in New Delhi, India as well as in Stockholm, Sweden.</p><p> </p>

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