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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.
141

Windmill driven water pump for small-scale irrigation and domestic use : In Lake Victoria basin

Salomonsson, Sara, Thoresson, Helena January 2010 (has links)
This project is a combination of mechanical engineering and sustainable development in developing countries. The goal has been to build a windmill driven water pump and to design a small-scale irrigation system for SCC-Vi Agroforestry’s demonstration farm in Musoma, Mara region, Tanzania. The purpose was to enable SCC-Vi Agroforestry to demonstrate and spread knowledge about these techniques to farmers in the region. In 2007, two students from Halmstad University conducted a field study in the Mara region and found that many farmers lack clean and running water. Back in Sweden they constructed a prototype of a windmill that employs wind energy to pump water using a semi-rotary pump. The intention is that local farmers should be able to build their own windmill, and thus have running water in their household. However, the windmill has never been built in Tanzania. The windmill construction in this report is based on the prototype, but the original drawings were changed to fit the specific situation in Tanzania better. Important throughout the project has been to minimise cost and to only use material that local farmers can get hold of. Building and assembling of the windmill were then performed by the authors in co-operation with local workers. The windmill drives a pump that pumps water from a well to a tank for further use in irrigation. Calculations have been made on the energy available in the wind and an energy analysis was then performed to see what wind speed is required for the system to work. If wind speed is low, the windmill can be adjusted by placing the connecting rod closer to the rotation centre where it requires less work to function. As a result of that, the volume of water per stroke will decrease and it will take longer time to fill the tank. This project was carried out during the rainy season when there is less wind; therefore the windmill has not been tested during optimal wind speed conditions. The tests that have been performed during the circumstances at the time showed that the performance of the windmill is consistent with the theoretical calculations. A proposed design for a simple drip irrigation system has been developed based on the conditions at the project area. It is constructed of plastic pipes with holes that emit water. Covers are in place to prevent soil from clogging the holes. Building the irrigation system was not part of this project.
142

Ekonomiska innovationer i den gotländska vindkraftsindustrin / Sources of funding for the wind power industry on Gotland

Carlzon, Jonathan, Lundborg, Rebecca January 2011 (has links)
Currently there is a controversial debate about that we must reduce our impact on the global warming; therefore both the Government and the local authorities have invested heavily in developing renewable energy in Sweden. The major development on the wind power market can be seen as a result of both the technological development and also on the decision that the Government took in 1996, which opened up the wind power market for private parties. This paper has aimed to examine the types of financial innovations that have arisen from the investments and financing of wind power on Gotland, and what these innovations can contribute to the future development of wind power. The problems that this thesis is based on is; what kind of financial innovations have occurred within investment and financing of wind power? How can these innovations contribute to the continued development of wind power on Gotland? The conclusion of this study shows that respondents and participants have defined a number of financial innovations that have emerged. Where some of the innovations only can be seen as incremental since they are based on continuous improvements, while others can be seen as radical as they are completely new for the context in which they operate. The study has also shown that Gotland has a great potential to produce more renewable electricity, but the development is dependent on the new power lines being built, in order to export electricity to the mainland.
143

Windmill driven water pump for small-scale irrigation and domestic use : In Lake Victoria basin

Salomonsson, Sara, Thoresson, Helena January 2010 (has links)
<p>This project is a combination of mechanical engineering and sustainable development in developing countries. The goal has been to build a windmill driven water pump and to design a small-scale irrigation system for SCC-Vi Agroforestry’s demonstration farm in Musoma, Mara region, Tanzania. The purpose was to enable SCC-Vi Agroforestry to demonstrate and spread knowledge about these techniques to farmers in the region.</p><p>In 2007, two students from Halmstad University conducted a field study in the Mara region and found that many farmers lack clean and running water. Back in Sweden they constructed a prototype of a windmill that employs wind energy to pump water using a semi-rotary pump. The intention is that local farmers should be able to build their own windmill, and thus have running water in their household. However, the windmill has never been built in Tanzania.</p><p>The windmill construction in this report is based on the prototype, but the original drawings were changed to fit the specific situation in Tanzania better. Important throughout the project has been to minimise cost and to only use material that local farmers can get hold of. Building and assembling of the windmill were then performed by the authors in co-operation with local workers. The windmill drives a pump that pumps water from a well to a tank for further use in irrigation.</p><p>Calculations have been made on the energy available in the wind and an energy analysis was then performed to see what wind speed is required for the system to work. If wind speed is low, the windmill can be adjusted by placing the connecting rod closer to the rotation centre where it requires less work to function. As a result of that, the volume of water per stroke will decrease and it will take longer time to fill the tank. This project was carried out during the rainy season when there is less wind; therefore the windmill has not been tested during optimal wind speed conditions. The tests that have been performed during the circumstances at the time showed that the performance of the windmill is consistent with the theoretical calculations.</p><p>A proposed design for a simple drip irrigation system has been developed based on the conditions at the project area. It is constructed of plastic pipes with holes that emit water. Covers are in place to prevent soil from clogging the holes. Building the irrigation system was not part of this project.</p>
144

Wind Turbine Production losses in Cold Climate : case study of ten wind farms in Sweden

Malmsten, Jon January 2011 (has links)
As wind power expands rapidly worldwide, it is becoming more common to build wind farms in alpine locations where the wind resources often are good and conflicting interests are few. This is evident in Sweden where a substantial portion of the large wind parks planned are to be built in cold climate locations. The fact that icing of turbine blades and sensors can severely impact the production raises the question how large the losses are. In this thesis 10 wind parks comprising 45 turbines, well dispersed throughout Sweden are investigated. Daily production figures are compared to wind data from the MERRA reanalysis data-set in order to see if it is possible to determine the level of losses during the winter period caused by cold climate. A method is suggested where a relationship between daily production and daily average wind speed is established using representative summer days. This relationship is then used to calculate an expected production for the winter period. Losses are concluded as the difference between expected and actual production. The method did not produce a consistent and reliable result for the sites investigated. However, the method captures the overall trend with higher losses in the north of Sweden compared to the sites in the south where little or no icing is likely. At the sites where icing is expected, losses in the range of 10 to 20% of the annual production were calculated.
145

Mean Wind and Turbulence Conditions in the Boundary Layer above Forests

Arnqvist, Johan January 2015 (has links)
As wind turbines have grown, new installation areas become possible. Placing wind turbines in forested landscapes introduce uncertainties to the wind resource estimation. Even though close-to-canopy processes have been studied intensively during the last thirty years, the focus has mostly been on exchange processes and the height span of the studies has been below the rotor of a modern wind turbine. This thesis contains analysis of new measurements from a 138 m high tower in a forested landscape. The previous knowledge of near-canopy processes is extended to the region above the roughness sublayer. It is shown that above the roughness sublayer, the surface layer behaves as over low vegetation, and Monin-Obukhov similarity is shown to hold for several variables. However, in stable stratification, effects that could be linked to the boundary layer depth are shown to be present in the measurements. These include wind turning with height, the behaviour of the turbulence length scale and the curvature of the wind profile. Two new analytical models are presented in the thesis. One is a flux-profile expression in the roughness sublayer, which allows for analytical integration of the wind gradient. The model suggests that the roughness-sublayer effect depends on stratification and that the aerodynamic roughness length changes with stability. A decrease of roughness length in stable stratification is confirmed with a new method to determine the roughness length using measurements from the 138 m tower. The other model determines the spectral tensor in stable stratification using analytical solution to the rapid distortion equations for stratified shear flow, with homogeneous stratification and shear. By using a formulation for the integration time of the distortions of an isotropic spectrum, a model is derived which provides the cross spectra of velocity and temperature at any two given points in space. Finally the existence of waves in the wind over forests is investigated and it is concluded that the Kelvin-Helmholtz instability can create waves which are coherent in time and exist over the entire height span of wind turbine rotors. Linear wave theory is shown to be able to explain certain features of the waves. / Vindforsk III, Wind power in forests / Vindforsk IV, Forest wind
146

En obruten fjällmiljö och konflikten med vindkraften : En studie om rumsliga landskapspreferenser och vindkraftens påverkan på de svenska fjällen

Haeffner, Oscar January 2014 (has links)
De svenska fjällen skyddas i dagsläget av miljömålet Storslagen fjällmiljö, ett mål som ämnar bevara fjällens ursprunglighet och därmed skydda dem mot ingrepp. Den svenska regeringen har även inrättat 13 områden klassade som obruten fjällmiljö, områden vars natur- och kulturvärden ska värnas om och som, i så stor utsträckning som möjligt, ska hållas orörda. Båda dessa skyddsformer hotas nu av de planer som finns på att bygga ut vindkraften i landet. I denna studie undersöks den visuella påverkan som finns från dagens vindkraftverk samt den ökade visuella påverkan som genom fattade beslut är på väg. Metoden för studien är en rumslig GIS-analys som undersöker hur stora områden som vindkraften påverkar visuellt. Detta kopplas sedan till studier kring platskänsla, platsidentitet och vindkraftens konflikt med landskapet. Studien har visat att vindkraftverken i de svenska fjällen har en signifikant visuell påverkan på de obrutna fjällen och att miljömålet Storslagen fjällmiljö i dagsläget inte ser ut att uppnås. Dock måste nämnas att hur den framtida förändringen av landskapsbilden i de svenska fjällen kommer att uppfattas till stor grad beror på varje individs koppling till landskapet som förändras. / In the Swedish mountains the government has established 13 areas, covering around 10 % of the country, as areas of undisturbed mountain regions. These areas are to be protected against activities threatening environmental and cultural values. There is also an environmental goal aiming to maintain the originality of the Swedish mountains called Storslagen fjällmiljö, in translation: A magnificent mountain landscape. These two factors are being threatened by the future plans of increasing the number of wind turbines in these areas. In this study the visual effects of the existing and not yet existing wind turbines are being examined by performing a GIS-analysis. This is analyzed based on place sensitivity and people’s relation to their surrounding landscape. The study has shown that wind turbines have a significant visual impact on the undisturbed mountain regions and that the environmental goal aiming to keep the originality of the mountains does not reach its target. However, it must be pointed out that this future change in the scenic landscape of the Swedish mountains also can be seen as something good, this depending strongly on your relationship with the landscape.
147

Vindkraft och lokala förankringsprocesser : Perspektiv på deltagande, förståelse och acceptans / Wind Power and Local Consultation Processes : Perspectives on Participation, Understanding, and Acceptance

Mels, Sanna January 2016 (has links)
This study examines different meanings attached to and practices adopted during Swedish local consultation processes on offshore wind power projects. It analyses the role played by those processes in a democratic planning context, as well as the ways in which they are implemented. It also identifies overarching process models. The study is informed by theories on democracy, planning, participation, communication, and media. The empirical material comprises three case studies, each examining experiences of local consultation processes for wind power projects that led to differences in local reception. Methodologically, the study triangulates analyses of semi-structured interviews, documents and news articles. The results show that, in a Swedish context, the role of local consultation processes is to create legitimacy and trust in the process and planning decisions. The complex dynamics become evident in the different forms of participation, knowledge generation, and communication employed during the consultation. This is shown to be the result of various democratic and planning attitudes to locally-situated interests and knowledge, which in turn lead to differing views on local understanding for and acceptance of project proposals. The study develops three schematic models that correspond to different types of consultation processes. An important conclusion is that the content and form of local consultation processes depends on the agency of several actors on different scales. They are not simple pre-designed by project planners, but the result of a far more complex interaction between a host of local actors, including officials, local media, and local communities. The categorisation of different local consultation processes could contribute to awareness about the implications of various ways of working with large-scale projects from local perspectives. / I den här avhandlingen undersöks lokala förankringsprocesser med ett särskilt fokus på havsbaserade vindkraftsprojekt. Diskussionen uppehåller sig vid frågor om förankringsprocessens roll i en svensk planeringskontext, samt hur olika utformningar av processen kan påverka det lokala mottagandet. Studien visar att förankringsprocesser ytterst handlar om legitimitet och tillit. I praktiken förekommer en stor variation, komplexitet och dynamik i lokala förankringsprocesser. Det yttrar sig bland annat genom olika former av deltagande, kunskapsbyggande och kommunikation. Centralt i resonemangen är demokratiska och planeringsmässiga förhållningssätt till platsbundna intressen och kunskaper. På så sätt tydliggörs skillnader i synen på förståelse och lokal acceptans avseende ett projektförslag. Genom studien urskiljs också tre schematiska förankringsmodeller som belyser sådana skillnader. Förståelse för lokala förankringsprocesser har betydelse inte minst avseende påverkan på lokal acceptans för storskaliga projekt.
148

Djuren och naturens värde mot grön energi : En analys av miljökonsekvensbeskrivningar inom vindkraft för prioritering av djur ochnatur jämfört med andra intressen / Animals and nature's value against green energy : An analysis on environmental impact assessment’s in wind power on their prioritising ofanimals and nature compared to other interests

Ahlin, Nina January 2021 (has links)
Syftet med denna uppsats är att undersöka hur Miljökonsekvensbeskrivnings (MKB)dokument på vindkraft prioriterar djur och natur jämfört med andra faktorer, för dennauppsats grön energi. Grön energi i dagens samhälle värdesätts högt då det är steg närmare enhållbar framtid. MKB dokumentens syfte är att lyfta fram konsekvenser som sker till följd aven åtgärd/verksamhet. Men MKB dokument har lång väg att gå då det finns brister iprocessen.  Dessa brister beror till viss del på en avsaknad av fungerande teoretiska ramar förMKB utredningar, och dels på hur beställare och författare till MKB dokumenten påverkas avsin omgivning. I uppsatsens fall den rådande kulturen och hur samhällets syn på människansrelation till naturen och djuren är. Resultatet av uppsatsen blev: Djur och natur får ofta ståtillbaka för mänskliga intressen som värderas högre. Exempel på dessa intressen är merförnybar energi, konsekvenser för människor och deras samhälle i form av begränsadframkomst på området. En förändrad landskapsbild. Oljud, skuggtimmar och iskastning. / The purpose of this essay is to research how Environmental Impact Assessment (EIA)documents for wind power prioritises animals and nature compared to other factors, for thisessay it is green energy. Green energy in today’s society is valued high for a more sustainablefuture. EIA in Sweden has the purpose to show the consequences of an action/operation. ButEIA documents have a long way to go, because there are shortcomings in the process. Theseshortcomings are partly due to the lack of proper theoretical frameworks for EIA, and in partdue to how the authors and those who request an EIA document are affected by their society.In the essays case the dominant culture and society’s view on the relationship between manand nature and the animals there. The result of the essay is: Animals and nature often gets tostand back in the face of human interest, which is valued higher. Examples of interest are,renewable energy, consequences for humans and society in the form of limited access to thearea. A changed landscape picture (ethical value), noises, shadow hours and ice throwingfrom the rotor blades.
149

Ekonomiska förutsättningar för vätgasproduktion som stöd till vindkraft

Nilsson, Henrik, Larsson, Christoffer January 2020 (has links)
Världen står inför utmaningen att minska sin klimatpåverkan som till en del beror på utsläpp av växthusgaser såsom koldioxid. Detta samtidigt som behovet av energi spås öka markant. Förnybara källor, företrädesvis vind- och solkraft, spås öka sin andel av den globala energiförsörjningen. Förnybar elkraftgenerering är dock inte oproblematisk då produktionen är svår att förutspå. När solen lyser eller vinden blåser sammanfaller dessutom inte alltid med när behovet av elektricitet finns vilket skapar stabilitetsproblem i elnätet. Att lagra energi för att sedan kunna återföra är ett sätt att både lösa stabilitetsproblem i elnätet och säkerställa att energi finns när den behövs. I den här studien undersöks möjligheten att, med el från vindkraft, genom elektrolys framställa vätgas som sedan lagras för att senare återföras som el via bränslecell eller säljas som råvara. Avsikten är att motverka negativa ekonomiska konsekvenser vid försäljning av intermittent vindkraft. I studien används modeller som gör simuleringar utifrån historiska data för 2019 från en vindpark. Detta för att undersöka om regleravgifter vid prognosavvikelser går att undvika eller delvis motverka samt om det går att flytta elproduktion i tid med en vätgasanläggning för att förbättra det ekonomiska utfallet för en vindkraftsproducent. Resultaten visar att detta i dagsläget inte är lönsamt utifrån de antaganden som gjorts. Detta främst för att alltför få drifttimmar uppnås i båda fallen. Studien visar att det dock kan vara lönsamt om syftet är att producera vätgas istället för att vara ett stöd för en vindkraftsproducent. / The world faces the challenge of reducing the emissions of greenhouse gases in order to mitigate climate change. At the same time, global energy demand is predicted to increase significantly. Renewable power generation like wind and solar power are believed to dominate the increase of needed power generation. These renewables power sources do not come without problems. Power fluctuations, due to their variable production causes grid stability problems and does not necessarily correspond to the demand for energy. Energy storage is a possible solution for both grid stability as well as for non-corresponding production/demand situations. This study investigates the feasability of hydrogen production by water electrolysis with electricity from a wind park. The produced hydrogen could either be sold or stored and used in a fuel cell to generate electricity at a later point in time. The aim is to mitigate negative economic consequenses from selling intermittent wind power. In the study simulations are made with historic data from 2019 from a wind park. Two models were created to investigate if imbalance costs due to forecast errors could be avoided or partially avioded and to investigate the possibility to move production of electricity in time and avoid unfavourable spot market prices. This in order to enhance the finacial results. The results from the study shows that at the present moment this is not a profitable approach with the assumptions made. The foremost reason for this is that too few system operating hours is obtained in each case. However, the results also shows that if the objective shifts from supporting wind power to producing hydrogen, the outcome could be profitable.
150

Technology and Volume Uncertainty in a Tradable Green Certificate System : Lessons from the Swedish-Norwegian system / Teknologi- och volymosäkerhet i ett elcertifikatsystem : En studie av det svensk- norska elcertifikatsystemet

LÖWING, WILHELM, BERG, HENRIK January 2015 (has links)
The global emission of greenhouse gases is perceived as one of the most prominent threats to the world today and a socio-technological transformation (STT) of the energy industry is considered essential for long term sustainability. Organisations’ decisions to participate in the diffusion of electricity generation from renewable energy sources (RES-E) are deemed essential for achieving the transformation. Governments have therefore introduced support systems promoting RES-E, and since 2003 a radable green certificate (TGC) system has been used to support increased diffusion. However, there are a number of uncertainties regarding investments in onshore wind power which may, or may not demotivate investors to take further part in the diffusion of the technology. Understanding the magnitude and impact of uncertainties is of interest as they can act as barriers for achieving STT. This thesis contributes to the understanding of uncertainties in the Swedish-Norwegian TGC system by exploring two groups of uncertainties; technology uncertainty and volume uncertainty. Evaluation of the technology and volume uncertainty in the Swedish-Norwegian TGC system has been performed by statistically investigating the relationship between technological development of onshore wind power and the certificate price, as well as the accumulated surplus of certificates and the certificate price. The surplus of certificates accumulated on the Swedish-Norwegian TGC market has also been tracked to its source of origin. In addition, the financial results of previous onshore wind power investments have been estimated. The results have been validated by interviews with Swedish wind power investors. The results indicate that both the technology development of onshore wind power in Sweden and the accumulated surplus on the market have impacted the price of certificates, and thus also the profitability of investors in the system. The technology development of onshore wind power has been difficult to forecast, resulting in a considerable technology uncertainty perceived by investors. Regarding volume uncertainty, of the total accumulated surplus of certificates at the end of 2014, 70 % can be derived from forecast errors of quota obliged electricity production by the Swedish Energy Agency. In addition, there is a possible relationship between lower costs of onshore wind power and the accumulated surplus of certificates on the Swedish-Norwegian TGC market. The major implication of these uncertainties is that previous investors choose to delay or refrain from further onshore wind power investments. If actors choose not to participate in further diffusion of the technology, this could potentially harm the STT of the energy industry in Sweden. Introduction of long term contracts, more frequent quota adjustments and a record of RES-E investment decisions could potentially reduce the uncertainties perceived by investors. / De globala utsläppen av växthusgaser anses av många vara samtidens stora utmaning och en socioteknisk omställning av energisektorn framhålls som en nödvändighet för en hållbar framtidsutveckling. Elproducenters deltagande i utbyggnad och utveckling av förnyelsebar elproduktion förespråkas som en viktig del av denna omställning. I led med den politiska agendan har flertalet stödsystem utvecklats vars mål är att stödja utbyggnaden av förnyelsebar elproduktion. I Sverige introducerades 2003 ett stödsystem med gröna elcertifikat vars mål är att främja utbyggnaden av förnyelsebar elproduktion i landet. Stödsystemet till trots är investeringar i landbaserad vindkraft i Sverige fortfarande  associerat med stor osäkerhet i form av teknologins och marknadens framtida utveckling. Dessa osäkerheter kan hämma fortsatt utbredning av förnyelsebar elproduktion vilket kan leda till fördröjning eller stagnation av den nödvändiga omställningen mot en hållbar energisektor. Denna examensuppsats bidrar med kunskap kring de osäkerheter som råder inom det svensk-norska certifikatsystemet genom att undersöka två huvudsakliga osäkerheter; teknikutveckling samt överskott av certifikat på marknaden. Osäkerheten kring teknologins utveckling har undersökts genom att statistiskt utforska ett möjligt samband mellan teknologins kostnadsutveckling och marknadspriset av elcertifikat. Volymosäkerheten på marknaden har undersökts på ett liknande sätt där ett möjligt samband mellan överskottet av elcertifikat och marknadspriset av elcertifikat har utforskats statistiskt. Vilka faktorer som bidrar till överskottet av elcertifikat på markanden och från vilka källor dagens ackumulerade överskott härstammar har identifierats. Vidare har lönsamheten för tidigare investeringar i landbaserad vindkraft i Sverige uppskattats och analyserats. Resultaten antyder att såväl teknikutveckling som överskott av elcertifikat har haft en  etydande påverkan på marknadspriset av elcertifikat. Detta har i sin tur påverkat lönsamheten för investerare i systemet. Teknikutvecklingen har varit svår att förutse vilket resulterat i att investerare upplever stor osäkerhet kring framtida lönsamhet. Vidare visar resultaten att 70 % av det totala överskottet av elcertifikat på marknaden vid slutet av 2014 har sitt ursprung i Energimyndighetens felaktiga prognoser av kvotpliktig elanvändning. Det är även troligt att det finns ett samband mellan teknikutvecklingen och det överskott av elcertifikat på som genererats på marknaden. Innebörden av de två analyserade osäkerheterna är att investerare potentiellt fördröjer eller helt avstår från fortsatta  investeringar. Detta är problematiskt då det kan hämma utbredningen av förnyelsebar  lproduktion och verka som ett hinder för omställningen mot en mer hållbar energisektor i Sverige. Genom att introducera långtidskontrakt för handel med elcertifikat, mer frekventa kvotjusteringar samt etablera ett register över investeringsbeslut kan den osäkerhet som investerare i systemet upplever idag minskas.

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