• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 53
  • 19
  • 11
  • 6
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 113
  • 113
  • 38
  • 38
  • 28
  • 26
  • 23
  • 19
  • 17
  • 16
  • 16
  • 13
  • 13
  • 12
  • 10
  • 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.
11

Renewable Portfolio Standard : an analysis of design and implementation issues /

Parvanyan, Tigran. January 2005 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 2005. / Typescript. Includes bibliographical references (leaves 95-100).
12

Photovoltaics for educational television in rural schools

Cowan, William Douglas January 1989 (has links)
One application for photovoltaic (PV) technology is in providing electricity for educational aids, in developing areas remote from grid supply. Technical, social and economic aspects of this option are investigated, in local context, by examining the use of small PV systems to power educational television and video in secondary schools in Bophuthatswana. Technical performance was assessed through monitoring PV system behaviour and climatic variables over an extended period, using remote data-capture techniques at a demonstration site. Modelling provided for further prediction of performance in nonobserved conditions. Social and educational aspects of the schools television project were investigated through interviews with educationists, planners, project administrators and a limited sample of teachers and pupils in Bophuthatswana. Overall conclusions are that PV systems can provide a reliable and technically appropriate solution to the problem of powering light electrical loads in off-grid schools. Levelised unit energy costs can be acceptable if PV systems are critically sized, and if there is close match between designed capacity and actual load energy demand. If this is not the case - as in Bophuthatswana school systems - unit energy costs may be very high. Organisational features of project implementation and inadequate central resources, particularly for delivering appropriate educational software to schools, have impaired the potential of the project, and the equipment in schools is under-utilised. Proceeding from an inductive performance analysis of the monitored system, a PV system performance model was developed, in order to assess the optimum sizing of components in small stand-alone photovoltaic systems in such applications, and to judge the sizing of the systems installed. The model is based upon critical runs of adverse weather, leading to-wards system loss of power to load. It predicts the minimum insolation required to avoid system loss of power to load over runs of days, and compares this with percentiles for plane-of-array insolation over runs of days, derived from long term · hourly weather station records. The approach allows development of a loss of power probability (LOPP) sizing methodology which preserves the run-length characteristics of local climatic data. Sizing predictions from this method are compared with other sizing methodologies, and are used to indicate design savings possible for the monitored systems. The proposed critical-run LOPP sizing method has potential for incorporation in a microcomputer-based sizing tool, suitable for more accurate design of photovoltaic systems with battery storage in local applications.
13

The difficulties faced by African utilities to secure finance for infrastructure development : energy sector

Mkhonta, Ernest Sipho Godfrey 04 1900 (has links)
Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Expansion of electricity generation and transmission infrastructure in Sub-Saharan Africa is on a very slow path compared to the demand and is by far lower than the potential demand. The projects needed to bridge the gap demand high capital input from the project sponsors. Securing finance to bring the generation expansion and new transmission line project into operation is difficult for utilities from small economies. The study contained in this document intends to investigate the difficulties faced by utilities to secure funding as they make efforts to meet the demand for electricity in their own countries and contribute to the regional electricity supply. Often projects are delayed because utilities have not fulfilled the strict requirements of the financial institutions. The research is limited to the two utilities and a sample of the development finance institutions that traditionally support these two countries with facilities for development. Data was collected from senior officials of the utilities and institutions involves using questionnaire and interview questions and analysed using statistical tools and inductive methods. The difficulties were divided into four major themes were found through the study. These are economic issues, financial issues, capacity issues and governance issues. The utilities need to be assisted in order to deal with these difficulties. The industry needs reforms are to truly liberalise it and allow other players in particular the private sector to participate in power generation. The impact of this would be the relaxation of the entry barriers for independent power producers and a better framework for public private partnerships.
14

A comparative study of the woodfuel crisis and rural energy planning in India and China

Tsa, Tak-yan, Dane., 謝得恩. January 1992 (has links)
published_or_final_version / Comparative Asian Studies / Master / Master of Arts
15

Public attitudes and perceptions of wind energy development within the Rolling Plains and Breaks ecological region

Tucker, Terry January 1900 (has links)
Master of Regional and Community Planning / Department of Landscape Architecture/Regional and Community Planning / John W. Keller / The Great Plains possesses one of the best sources of wind energy in North America. Based upon the need to diversify energy production domestically, wind energy’s future in both the immediate and long term should be dynamic. The success of wide scale development of this potential will be largely determined by the perceptions of local residents, who are most affected by the siting and design of wind energy projects. Currently, regulation of this natural resource is left largely to state and county governments. A majority of these entities in the Great Plains region have no regulations governing wind energy development or employ a patchwork of "borrowed" codes from across the nation. The system of regulation of natural resources by political boundary is archaic. It fails to recognize that there are high degrees of correlation between social, economic, and natural resources without respect for artificial political boundaries. This study is the first in the Great Plains to examine public attitudes toward the development of wind energy and its relationship to the landscape based upon ecological regions rather than political boundaries. The analysis of collected data will provide a useful tool for local planners, policy makers, and the general public in understanding the prevalent issues involved with wind energy development in this region.
16

Palladium supported graphene oxide based metal organic framework composite for hydrogen technology

Makhafola, Mogwasha Daphney January 2019 (has links)
Thesis (M.Sc. (Chemistry)) -- University of Limpopo, 2019. / The concept of sustainable energy development is one of the crucial topics of the 21st century. It has evolved into a guiding principle for a liveable future world where human needs are met while maintaining balance with the environment. In this regard, hydrogen technology is a promising alternative energy source since it does not produce undesirable greenhouse gas (CO2). In order to place hydrogen energy into practical applications, there are certain problems that need to be addressed, these include the efficient production and storage of hydrogen. Currently, hydrogen is mostly produced from conventional processes such as steam reforming of fossil fuels, gasification and water splitting (photo/electrochemical and thermochemical). Among these methods, electrochemical water splitting is identified as a noble process to produce clean hydrogen gas and monitor all processes through hydrogen evolution reactions (HER). The entire HER processes are sluggish in nature and cathodic electrocatalysts are utilised to accelerate the process. Hence, in this work, we present highly active graphene oxide/metal organic framework (GO/MOF) and palladium (Pd) supported GO/MOF electrocatalysts for HER. GO/MOF was prepared through impregnation method of MOF and GO, whereas Pd@GO/MOF composite was synthesised using electroless Pd deposition on GO and followed by impregnation method of direct mixing of Pd@GO and MOF. The structural, morphological and electrochemical properties of the synthesised materials (GO/MOF and Pd@GO/MOF) were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR), simultaneous thermogravimetric analysis (STA), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), high resolution transmission electron microscopy/Energy dispersive x-ray spectroscopy/selected area electron diffraction (HRTEM/EDX/SAED) and cyclic voltammetry (CV). XRD, FTIR, TGA and DSC results revealed the presence of GO on MOF confirming the formation of composites. The SEM/EDS and HRTEM/EDX/SAED results confirmed the presence of octahedral structure of MOF in the Pd@GO sheet-like structure, elemental composition and crystallinity of the synthesised materials. Furthermore, the electrocatalytic efficiency of GO/MOF and Pd@GO/MOF composites on HER was studied using three important parameters (exchange current density, Tafel slope and charge transfer coefficient) calculated from Tafel analysis. The GO/MOF and Pd@GO/MOF composites showed excellent HER activity at 0.45 mol.L-1 H2SO4 withexchange current densities of 25.12 A.m-2 and 24.5 A.m-2, Tafel slopes of 116 mV/dec and 123 mV/dec, and transfer coefficients of 0.49 and 0.52, respectively. These observed results are consistent with theory, thus suggesting the Volmer reaction as the limiting mechanism at high concentration. However, at low concentration both composites showed an increase in the Tafel slope and transfer coefficient, suggesting the reaction order of Volmer reaction coupled with either Heyrovsky or Tafel reaction. The proposed reaction order was further supported by slope of logarithm of current as a function of pH and Pourbaix diagram. The composites demonstrated the enhancement turnover frequency (TOF) values in this order MOF <GO/MOF <Pd@GO/MOF. The large TOF value of 7.81 mol H2.s-1 in the case of Pd@GO/MOF was due the H2 spillover effect as a result of the presence of Pd nanoparticles. The fabricated composites displayed high activity, good stability and excellent tolerance to the crossover effect, which may be used as a promising catalyst in electrochemical hydrogen production and storage technology via hydrogen evolution reaction.
17

Relacionamento planejadores energeticos e jornalistas : a analise da crise energetica de 2001 / Relationship of energy planners and journalists : the analysis of the 2001 energy crisis

Viana, Fabiana Gama 30 July 2004 (has links)
Orientadores: Vera Regina Toledo Camargo, Ennio Peres da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T09:52:06Z (GMT). No. of bitstreams: 1 Viana_FabianaGama_M.pdf: 2074407 bytes, checksum: e1153317a18b33fc3601c40ab9065f33 (MD5) Previous issue date: 2004 / Resumo: Estudar a relação entre planejadores energéticos do meio acadêmico e jornalistas no processo de divulgação científica, tendo como cenário a crise energética de 2001, e propor procedimentos para o aperfeiçoamento desta relação. Este é o trabalho "Relacionamento planejadores energéticos e jornalistas: a análise da crise energética de 2001", que apresenta a relação entre planejadores energéticos e jornalistas e como este relacionamento pode ser favorável a estes dois profissionais e atender os interesses da sociedade. A pesquisa, em se tratando de um estudo interdisciplinar e através de uma revisão bibliográfica, proposta como metodologia, busca apresentar detalhadamente como são desenvolvidas as atividades destes dois profissionais para que um possa entender a realidade do outro e, com isso, procurar melhorar os entendimentos de uma boa relação. A crise energética de 2001 foi escolhida como cenário do estudo, por se tratar de um evento mobilizador da sociedade na compulsória economia de energia / Abstract: The study of relations between academic energy planners and journalists in the process of scientific divulgation, having the 2001 energy crisis as the scenario and the proposal of procedures to improve this relationship, are the basis of this work, which presents this connection and the manners in which it can be favorable to both of these professionals while also attending the interests of society. Since this research deals with an interdisciplinary study, through a bibliographic revision proposed as a methodology, it attempts to present in detail the manner in which the activities of these two professionals are developed so that one is able to understand the reality of the other, thus promoting a good relationship. The 2001 energy crisis was chosen as a scenario for this study because it was an event that mobilized society due to the compulsory economy of energy / Mestrado / Planejamento de Sistemas Energeticos / Mestre em Engenharia Mecânica
18

Appropriate technology and the rural energy sector in South East Asian developing countries

Subbakrishna, Nagendra January 1988 (has links)
Given increasing problems in the availability, affordability and deliverability of commercial primary and secondary energy resources, coupled with growing macroeconomic uncertainties, the use of renewable, non-commercial energy resources has been actively promoted in rural areas of developing countries. This, in addition to the fact that conventional, 'state-of-the-art' energy facilities present technical problems, are inequitable and pose potential environmental hazards, has led to proposals for instituting alternative, intermediate or 'appropriate' technologies in rural settlements. This thesis identifies technical, economic, social, cultural and institutional barriers to the introduction of intermediate or 'appropriate' technologies in rural areas. The cases of solar and biogas technologies in Korea, Malaysia, Papua New Guinea the Philippines and Thailand are considered. Policy and planning process recommendations are made on the roles of government, voluntary aid-agencies and the rural user, to overcome the obstacles to implementing these technologies. These recommendations cover the micro (village) and macro (regional and national) levels over two time horizons, and stress the need for a comprehensive approach to discerning rural needs, followed by integrated technology diffusion through effective program and project implementation. In addition, this thesis identifies the need for a continuous collection of information on rural socio-economic conditions and potential for rural interfuel substitution and finally, recommends research into improving technical efficiencies of alternative energy technologies such as solar and biogas. Alternative or intermediate energy technologies such as solar and biogas can play an important role in augmenting rural energy supply. Unless steps are taken to remove the identified barriers to implementation in future technology diffusion efforts, this potential will not be realized. Policy and planning process recommendations made in this thesis present means through which these barriers could be removed. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate
19

Elucidation of Photoinduced Energy and Electron Transfer Mechanisms in Multimodular Artificial Photosynthetic Systems

Lim, Gary Lloyd 05 1900 (has links)
Multimodular designs of electron donor-acceptor systems are the ultimate strategy in fabricating antenna-reaction center mimics for artificial photosynthetic applications. The studied photosystems clearly demonstrated efficient energy transfer from the antenna system to the primary electron donor, and charge stabilization of the radical ion pair achieved with the utilization of secondary electron donors that permits either electron migration or hole transfer. Moreover, the molecular arrangement of the photoactive components also influences the route of energy and electron transfer as observed from the aluminum(III) porphyrin-based photosystems. Furthermore, modulation of the photophysical and electronic properties of these photoactive units were illustrated from the thio-aryl substitution of subphthalocyanines yielding red-shifted Q bands of the said chromophore; hence, regulating the rate of charge separation and recombination in the subphthalocyanine-fullerene conjugates. These multicomponent photosystems has the potential to absorb the entire UV-visible-NIR spectrum of the light energy allowing maximum light-harvesting capability. Furthermore, it permits charge stabilization of the radical ion pair enabling the utilization of the transferred electron/s to be used by water oxidizing and proton reducing catalysts in full-scale artificial photosynthetic apparatuses.
20

An analysis of non-utility generation alternatives

Russell, Alexander George 14 April 2009 (has links)
Interest in BiCMOS technology has been generated recently due to the potential advantages this technology offers over conventional CMOS which enjoys widespread use in today’s semiconductor industry. However, before BiCMOS can be readily adopted by the VLSI community, an understanding of the design issues and tradeoffs involved when utilizing it, must be achieved. The principal focus of this research is to move towards such an understanding through the means of analytical modeling and circuit simulation using PSPICE [1]. The device chosen for the modeling approach is the basic BiCMOS Inverting Buffer Driver. The model yields equations that characterize output rise and fall transients and quantify the delays incurred therein. At the end of the analysis, we have a composite set of delay equations that are a measure of the total gate delay and reflect the importance of individual device and circuit parameters in determining this delay. Further investigations conducted to determine the influence of device, circuit and process parameters on BiCMOS, indicate that this technology is far more resilient to variations in such parameters than CMOS. At the end of this research, we are able to make a definitive judgement about BiCMOS performance and its superiority over CMOS in the switching speed domain. / Master of Science

Page generated in 0.0911 seconds