• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1139
  • 270
  • 103
  • 74
  • 68
  • 58
  • 47
  • 40
  • 25
  • 14
  • 13
  • 11
  • 10
  • 9
  • 8
  • Tagged with
  • 2264
  • 2264
  • 723
  • 565
  • 452
  • 320
  • 280
  • 261
  • 249
  • 246
  • 239
  • 209
  • 194
  • 175
  • 169
  • 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.
161

Multi-criteria assessment of wave and tidal power along the Atlantic coast of the southeastern USA

Defne, Zafer 11 January 2010 (has links)
The increasing demand for energy and the increased depletion rate of nonrenewable energy resources call for research on renewable alternatives. Mapping the availability of these resources is an important step for development of energy conversion projects. For this purpose, the wave power potential along the Atlantic coast of the southeastern USA, and the tidal stream power along the coast of Georgia are investigated in this study. Wave power potential is studied in an area bounded by latitudes 27 N and 38 N and longitudes 82 W and 72 W (i.e. North Carolina, South Carolina, Georgia, and northern Florida). The available data from National Data Buoy Center wave stations in the given area are examined. Power calculated from hourly significant wave heights and average wave periods is compared to power calculated using spectral wave energy density. The mean power within 50 km of the shore is determined to be low, whereas higher power is available further offshore beyond the 3500 m contour line. The tidal stream power potential along the coast of the state of Georgia is evaluated based on the NOAA tidal predictions for maximum tidal currents and three dimensional numerical modeling of the currents with Regional Ocean Modeling System (ROMS). The modeling results are validated against the available measurements. This region has low to moderate average tidal currents along most of the coast, but with the possibility of very strong local currents within its complex network of tidal rivers and inlets between barrier islands. Tidal stream power extraction is simulated with a momentum sink in the numerical models at the estuary scale to investigate effect of power extraction on the estuarine hydrodynamics. It is found that different power extraction schemes might have counterintuitive effects on the estuarial hydrodynamics and the extraction efficiency. A multi-criteria method that accounts for the physical, environmental and socioeconomic constraints for tidal power conversion schemes is proposed to select favorable locations and to rank them according to their suitability. For this purpose, the model results are incorporated into a Geographical Information System (GIS) database together with other geospatial datasets relevant to the site selection methodology. The methodology is applied to the Georgia coast and the candidate areas with potential are marked.
162

Competitive renewable energy zones in Texas : suggestions for the case of Turkey

Ogunlu, Bilal 20 July 2012 (has links)
As an energy-importing developing country, Turkey depends heavily on imported petroleum and natural gas. The increase in the global petroleum price has affected the Turkish economy adversely in the last decade. Renewable energy is an important alternative in reducing Turkey’s energy dependency. Turkey’s strategies are improving domestic production and diversifying energy sources for the security of supply. New investments, especially in renewables, have been chosen to achieve these objectives. As a model for Turkey, Texas is the leader in non-hydroelectric renewable energy production in the U.S. and has one of the world’s most competitive electricity markets. However, wind generation creates unique challenges for the Electric Reliability Council of Texas (ERCOT), the transmission system operator of Texas. The market environment has forced the Public Utility Commission of Texas (PUCT) to develop unique deregulated energy markets. In 2005, the Texas Legislature passed Senate Bill 20, in part to break the deadlock between transmission and wind generation development. This legislation instructed the PUCT to establish Competitive Renewable Energy Zones (CREZs) throughout the State, and to designate new transmission projects to serve these zones. In this context, first of all, the electricity market development in Turkey is introduced in terms of renewable energy, especially wind power. Next, considering wind power, the progress in the Texas electricity market is investigated. Subsequently, we examine the development of CREZs in Texas from a regulatory perspective and discuss Texas’ policy initiatives, including the designation of CREZs. Finally, we review the impact of wind power on the primary electricity market of Texas and evaluate market conditions and barriers to renewable energy use in Turkey in order to extract suggestions. This experience may be particularly instructive to Turkey, which has a similar market structure on the supply and transmission sides. This study suggests ways that Turkey might handle renewable applications in combination with existing transmission constraints. / text
163

Going solar in paradise : solar water heaters on the island of Hawaii

Murray, Julie Marie 20 November 2013 (has links)
Energy efficient technologies and renewable energy technologies are becoming less of a novelty in the American energy mix. These technologies offer the promise of a decreased dependence on foreign oil, considerable savings of energy bills, and protections for the environment. Despite the many potential benefits, these technologies face many barriers to adoption. The lack of renewable energy technologies and energy efficient technologies is particularly damaging in the State of Hawaii, where 90% of energy needs are met with imported fossil fuels. This report focuses on the current energy policies in Hawaii and the barriers to the incorporation of renewable energy technologies and energy efficient technologies, specifically solar water heaters. / text
164

Clean Development Mechanism : is it a tool to promote the use of renewable energy in South Africa?

Moosa, Nadia. January 2013 (has links)
Climate change, greenhouse gas emissions (GHG), and environmental pollution have all become buzzwords of our time. The awareness in recent years of the degradation of the planet by prioritising economic gain has allowed for open debate about the way the planet is being affected by development. However, there is wide consensus that development cannot be stopped or slowed down, but may be conducted in a sustainable way. The aim of this research is to investigate the role of Clean Development Mechanism (CDM) as a tool to promote the use of renewable energy in South Africa. The Kyoto Protocol was adopted in 1997, which stipulated that developed nations of the world would take on emission reduction targets to reduce their GHG emissions by five percent below 1990 levels. These emissions will be evaluated by the CDM Executive Board at the end of 2012 and penalties are payable should countries not meet their stipulated targets. South Africa is defined as a country (under CDM) which is eligible for hosting CDM projects, and does not have emission reduction targets. This research aims to explore the barriers to the successful implementation of CDM projects in South Africa, with a particular focus on renewable energy projects. In order to address the research problem, the theory of ecological modernisation (Mol, 1995; Hajer, 1995; Christoff, 1996) is applied to analyse the policy decisions around renewable energy, thus highlighting areas that need attention in order to make significant changes in the climate change policy decisions prevailing at the time of the study. Ecological modernisation is a policy orientated discourse which describes environmental issues in a particular manner. In the developing country context of South Africa, a case of weak ecological modernisation has been established (Christoff, 1996; Scott and Oelofse, 2005; Blowers and Pain, 1999). This is in part due to the weak participatory approach which has been adopted by government. This study had found that South Africa has robust and progressive policies in terms of environmental management and renewable energy. However, the area in which it seems to be failing is implementation. The results of this study show that CDM is not popular in South Africa due to a host of reasons. Funding and lack of implementation of projects seem to be the key factors. Eskom’s relatively low electricity price still hinders the wide spread implementation of renewable energy and energy efficiency projects. This study concludes that CDM projects have not succeeded in South Africa due to the bureaucratic process that CDM projects need to undergo coupled with the two issues mentioned above (funding and relatively cheap electricity). This is completely different compared to its other developing country counterparts like India, China and Brazil. This study was conducted at a time when the Kyoto Protocol was nearing its end. Should the agreement not be extended, it would be a lost opportunity for South Africa in terms of gaining technology transfer from the developed world as well as much needed funding for climate change projects. / Thesis (M.Soc.Sc.)-University of KwaZulu-Natal, Durban, 2013.
165

Renewable electricity from salinity gradients using reverse electrodialysis

Gilstrap, Matthew Coleman 20 September 2013 (has links)
Renewable power generation from the controlled mixing of sea and fresh water is relatively unexplored when compared to the development for solar, wind, and other sustainable power alternatives. When global river discharge was taken into account, an estimated 2.6 TW of obtainable energy exists in untapped salinity gradients. Reverse electrodialysis is one proposed power-generating mechanism for harnessing energy from brackish environments and relies on the transport of aqueous salt ions through an apparatus of ion-exchange membranes. In this thesis, operational parameters, including flow direction, salinity composition, and membrane selectivity, are investigated. For optimal performance, I have employed counter-current flow mode with monovalent ion selective membranes and pure 0.5 M NaCl saline solution. The results show that a maximum open circuit voltage (OCV) level of 2.01 V is obtained with an active membrane area of 0.0756 m². The presence of multivalent ions in the feed solutions hinders OCV levels, but the effects are reduced with monovalent-selective membranes. Preliminary results are insightful; in order to increase the commercially viability of this technology, future work is needed to enhance the performance properties of the ion exchange membranes.
166

The effects of alternative energy on Saudi Arabia and the implications for U.S. national security /

Yaggi, Danielle Nicole, January 1900 (has links)
Thesis (M.S.)--Missouri State University, 2008. / "May 2008." Includes bibliographical references (leaves 128-136). Also available online.
167

The Icelandic Example: Planning for Hydrogen Fueled Transportation in Oregon / Planning for Hydrogen Fueled Transportation in Oregon

Fisher, Jeffrey Dean, 1966- 06 1900 (has links)
xii, 91 p. :ill. (some col.), maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The ability to provide an adequate supply ofrenewable energy necessary to offset the emissions of"zero emission" vehicles is of importance for Oregon's planners and policy makers. An increase in electricity generation caused by the electricity required for zero-emissions hydrogen fuel cell vehicles will result in an increase in greenhouse gas emissions ifrenewable energy is not installed to meet hydrogen fuel cell needs. What are the renewable energy implications for Oregon planners to consider for meeting future fuel cell zero emission vehicle (ZEV) needs? Work done in Iceland can serve as an example for Oregon's need for renewable energy to meet ZEV needs. Icelandic data about hydrogen generation and the renewable energy requirements necessary for ZEVs at the Gtj6thaIs hydrogen fueling station set a benchmark for Oregon planners to consider when figuring the impact of ZEVs. / Committee in Charge: Dr. Robert F. Young, Chair; Dr. Greg Bothun; Mr. Roger Ebbage
168

Nové trendy v energetice pro udržitelný rozvoj / Modern trends in energetics of sustainable development

Moric, Rostislav January 2012 (has links)
The aim of the thesis is to explain both the practical and theoretical aspects of the current trends in the development of sustainable communities. On the one hand, saving electricity and heat energy standards implementations - passive house, energy+, etc.; on the other hand, the possibilities of local communities supplying renewable electricity and heat in order to reach the highest share of renewable energy. In the practical part I will focus on the implementation of saving measures and the installation of renewable energy sources to a specific community. I will draw from the current architectural trends and the latest technologies for renewable energy sources.
169

Weak Power Grid Analysis for Renewable Energy Sources Integration

Aldaoudeyeh, Al Motasem January 2019 (has links)
Weakness analysis based on grid strength assessment is useful for identifying potential weak grid issues. However, when taking into account the impact of the interactions among Renewable Energy Sources (RESs), the weakness analysis becomes computationally challenging. Different combinations of PointsofInterconnections (POIs) of RESs may have different impacts on grid strength at each POI. Due to the combination nature, such weakness analysis may be time-consuming when identifying the weakest combination of POIs from a large number of potential candidate locations in realistic power grids. This dissertation addresses the topic of determination of the weakest RESs combinations. Based on impedance ratios as a criterion, the dissertation shows that the impacts of impedance ratios magnitudes and angles are ‘quasi-mutually exclusive’. Such a concept is then used to reduce the computational burden with a fast screening algorithm. To further understand the impact of network components on grid strength, vector-based interaction analysis is developed based on the concepts of operational transfer impedances and operational interaction operators. In particular, this dissertation shows how mathematical models of interaction of multiple RESs can be simplified by replacing them with equivalent impedances, allowing us to simplify the mathematical expressions that quantify interactions among RESs. The conclusions and concepts established based on simplified models are statistically tested for their applicability to the generalized interaction model. The result would be a more simplified mathematical representation of interaction among RESs. Finally, a new technique is presented to efficiently update the Bus Impedance Matrix (Zbus) following changes in the series impedance of a branch. Conventionally, such update requires redundant recalculations, which involve matrix inversion operations (i.e., inverting the Bus Admittance Matrix, Ybus) and thus cause high computational burden because of potential matrix ill-conditioning, especially for largescale power grids. This dissertation overcomes these shortcomings by deriving an analytical expression for changes in Zbus in terms of its old elements and the variation of the impedance of a given branch. Hence, the computation overhead is comparatively small, and no issues arise due to the new Ybus being ill-conditioned. Such contribution helps facilitate real-time applications of methods that rely on Zbus.
170

International Competitiveness of Wind Power Industry: : the case of GAMESA Corp. S.A

Batlle Linares, Oriol January 2011 (has links)
The modern lifestyle is highly dependent on the electricity consumption, which demand is expected to continue growing worldwide, especially in those developing areas where the whole economy is transforming. Until now, most of this electricity demand had been supplied through the combustion of fossil fuels or nuclear power. But the utilization of these energy sources to power the human activity is unsustainable because of limitless of the resources and the hazardous emissions and wastes that they generate. That is why since few decades ago thewind power became one of the best-positioned renewable energy in terms of costs effectiveness as a viable alternative to the energetic model based on pollutant fossil fuels. This technology was firstly developed and implemented on those countries with a traditional environmental conscientiousness, but as the global warming issue increased new countries were interested to use wind power as a clean and sustainable energy source. The growing wind power demand of developing countries has changed in few years the entire industry, because new local manufacturers have appeared thanks to the government renewable policy, which main objective is to develop a strong domestic wind power industry capable of lead the world transformation to a clean energy model. The thesis defines the most commons renewable energy policies, and focus in the policy used in China with the aim to analyze if it is promoting or damaging the expansion of wind power use because of the priority is protect its own domestic wind power industry from international firms. The conclusions are that those protectionist policies are useful in the early stage of the industry development but the government must know the exact moment in which these subsidies and supporting mechanisms become counterproductive. If those are used during a prolonged period, then companies become dependent on subsidies and don’t act like in free markets where the innovation is the key to gain and maintain sustainable competitive advantage.

Page generated in 0.0636 seconds