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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.
61

Future Energy Supply, Simulations with Limited Resources

Benichou, Léo January 2011 (has links)
Many different organizations publish energy scenarios, from International Energy Agencyto oilproducers, but also independent academic institutions or experts. Each of these scenarios presentsome particularities. They may also reflect the interests of the institutions producing them. Ifpolicy makers are to safely rely on some scenarios for planning and analysis, there is clear needfor awareness rising regarding energy scenarios and, more generally, the future energy constraint. The Shift Project think tank addresses energy and climate change constraints in the modern world.The double degree thesis work presented in this report is the result of a five month internshipwith the Shift Project. The work was dedicated to, on the one hand, the implementation of an onlineinformation platform gathering long term historical data and energy scenarios and, on the otherhand, the development of an analytical framework for energy scenarios. These tools bring a betterunderstanding of published scenarios first by providing a unique overview of the whole ‘scenariolandscape’ allowing making comparison on relative scales and questioning their credibility. Theobjective is to increase transparency around the assumptions and meaning of the scenarios. Thetools produced will help decision makers by providing transparent material and operative filters inthe wide information base of energy scenarios. Ultimately, they help highlight the keyissuesinfluencing the global energy agenda.
62

Analysis of simultaneous cooling and heating in supermarket refrigeration systems

Marigny, Johan January 2011 (has links)
In this master thesis project, conventional supermarket refrigeration systems using R404A are compared with refrigeration system solutions using natural refrigerants such as carbon dioxide and ammonia. This systems analysis considers the behavior of those systems in floating condensing and heat recovery mode. System heating and cooling COP have been calculated by using computer simulation with the calculation software EES (Engineering Equation Solver). The impact of important parameters such as sub-cooling, external superheating and compressor discharge was also determined through the computer models.The estimation of the system annual energy consumptions shows that systems using natural refrigerant can compete with systems using artificial refrigerant by using heat recovery system such as heat pump cascade, heat pump cascade for sub-cooling, fixed pressure system and de-superheater. If the indirect emission of systems using natural refrigerant and artificial refrigerant is approximately similar, the direct emission for carbon dioxide systems and ammonia systems can be estimated to be 10000 times less important than R404A systems.Multi-unit refrigeration systems have also been studied in this project; it appears that in theory COP improvement of 10% is possible if the condensing temperature of each unit is controlled adequatelly. / B
63

Potential for biogas production fromslaughter houses residues in Bolivia : Systematic approach and solutions to problems related to biogas production at psychrophilic temperature

Tesfaye Tefera, Tadious January 2011 (has links)
Residues from slaughter houses offer an abundant resource in Bolivia. The residues can beused for biogas production with biofertilizer as a bi-product. These resources are, however,currently not being used. Instead, they are released in water systems, implying heavycontamination, e.g., on the Lake Titicaca in western Bolivia. Severe environmental effects areobserved in the lake and connected water systems. The residues from slaughter houses are animportant part of the problem. If the contamination continues, important environmental values willbe lost. Information around the resource is scarce, since no extensive inventory has been carried out. It isestimated that officially registered slaughter houses in the four major cities of Bolivia aloneproduce over 75 tons of organic residues per day. This flow of residues has increased since theworld market for animal fodder based on blood dropped significantly. In addition, there is littleexperience of biogas production in cold environments at that altitude, almost4000 meters over sea level. Production of biogas from waste is one of the most common methods to generate energy and at thesame time best waste reduction methods. Biogas production can be practiced favoring one theextremities, that is, either for the purpose of energy production or waste reduction. In this thesis, the focus is on waste reduction, that is the slaughter houseresidues. Nevertheless, the ultimate outcome is always to reduce as much waste as possible and, atthe same time, generate profitable energy. There are many technological and financial challenges that have to be addressed to see the completerealization of the biogas concept. Therefore, this master thesis focus on producing biogas fromresidues of slaughter houses in the greater area around Lake Titicaca and studies whichtechnological issues have to be solved. Furthermore, analyzing how the biogas segment can befurther developed in Bolivia according to the appropriate technology selection is alsoinvestigated.
64

Effekten av en ökad andelsolceller på Linköpingslokalnät : En konsekvensanalys av Linköpings solelsmålgenom identifiering av kritiska områden medhänsyn till svaga nät och troliga adopters

Edvardsson, Astrid, Lundkvist, Nils January 2021 (has links)
Antalet installerade solcellsanläggningar i Sverige har ökat exponentiellt de senaste åren och iLinköping har kommunen antagit ett solelprogram som innebär att lokalproducerad solkraftska stå för fem respektive 20 procent av kommunens totala elanvändning år 2025 och 2040.Linköpings solelprogram förväntas leda till ökade installationer av solcellsanläggningar både iform av solkraftsparker och decentraliserade solpaneler som installeras på byggnader. Dennastudie fokuserar på utmaningarna som följer av decentraliserad solelsproduktion.Syftet med studien är att undersöka vilka fastighetsägare som har drivkrafter, hinder ochegenskaper som kan användas för att identifiera geografiska områden där installationen avsolpaneler på byggnader förväntas bli hög i framtiden. Genom att kombinera dessa parametrarmed identifiering av svaga elnät utvecklas metoden områdessegmentering, för att identifieraområden i elnätet med potentiellt stora utmaningar kopplade till ökad andel solceller. Vidareanvändes områdessegmentering för att ta fram ett fallstudieområde i Tekniska verken iLinköping AB:s lågspänningsnät. Fallstudieområdet användes sedan för att jämföra trenätåtgärder: nätförstärkning, energilagring och curtailment. Åtgärderna kan hantera deutmaningar som uppstår på grund av solelens intermittenta och dyngsvarierande karaktär ochanalyserades utifrån nyttjandegrad av energi och ekonomisk lönsamhet.Resultatet visade att småhusägare är den enda typ av fastighetsägare vars parametrar kanidentifieras för att tillämpas i områdessegmentering. De viktigaste parametrarna är relateradetill goda ekonomiska förutsättningar eftersom de ekonomiska hindren visats vara viktiga attöverkomma. Dessutom är även parametrar kopplade till fysiska förutsättningar, samt antaletgrannar som installerat solpaneler, viktiga faktorer för småhusägare i beslutsprocessen attsjälva installera. Gällande åtgärderna har nätförstärkning högst nyttjandegrad av energi,medan curtailment har lägst nyttjandegrad men också den lägsta årliga kostnaden. Batterilagermåste överdimensioneras effektmässigt för att närma sig samma nyttjandegrad somnätförstärkning och är i dagsläget inte ett ekonomiskt försvarbart alternativ. Däremotförväntas batteripriserna fortsatt sjunka och lönsamheten ökar troligtvis om batterilagringkombineras med andra elnätstjänster. Slutsatsen är att i nuläget antas nätförstärkningfortfarande vara den bästa åtgärden som Tekniska verken i Linköping AB kan vidta menalternativa lösningar blir mer och mer konkurrenskraftiga. Ytterligare utvärderingar avbatterilagring eller annan typ av energilagring i kombination med curtailment rekommenderasdärför eftersom det sannolikt kommer bli lönsamt inom en överskådlig framtid. / The number of installed photovoltaic systems in Sweden has increased exponentially in recentyears and in Linköping the municipality has adopted a solar program, Solelprogrammet, whichmeans that locally produced solar power will account for five and 20 percent of themunicipality's total electricity use in 2025 and 2040. Linköping's solar program is expected tolead to increased installations of photovoltaic systems in the form of both large solar powerplants and decentralized solar panels installed on buildings. This study focuses on thechallenges posed by decentralized solar power production.The purpose of the study is to investigate which property owners that have driving forces,barriers and characteristics that can be used to identify geographical areas where the potentialfor large installations of solar panels on buildings is high. By combining these three types ofparameters with the identification of weak electricity grids, a method was developed to identifyareas in the electricity network with potentially major challenges linked to an increasedproportion of solar cells. Furthermore, this method was used to identify a case study area inTekniska verken in Linköping AB's low voltage grid. The case study area was then used tocompare three grid solutions: network reinforcement, energy storage and curtailment. Themeasures can handle the challenges that arise due to the sun's intermittent and diurnal natureand were analyzed based on the degree of utilization of energy and economic profitability.The results showed that single-family homeowners are the only type of property owner whoseparameters can be identified for application in the developed method. The most importantparameters are related to good economic conditions as the economic barriers have been shownto be important to overcome. In addition, parameters linked to physical conditions, as well asthe number of neighbors who have installed solar panels, are important factors for homeownersin the decision-making process to install themselves. Regarding the solutions, gridreinforcement has the highest degree of utilization of energy, while curtailment has the lowestdegree of utilization but also the lowest annual cost. Battery storage must be oversized interms of power to approach the same utilization rate as grid reinforcement and is currentlynot an economically feasible alternative. On the other hand, battery prices are expected tocontinuously fall, and the profitability is likely to increase if battery storage is combined withother grid services. The conclusion is that at present, network reinforcement is still assumedto be the best measure that Tekniska verken i Linköping AB can take, but alternative solutionsare becoming more and more competitive. Further evaluations of battery storage or other typesof energy storage in combination with curtailment are therefore recommended as it is likely tobe profitable in the foreseeable future.
65

A new energy model for the Lakshadweep islands : Change from a diesel-based model to a hybrid model with renewable energy systems considering the ecological fragility of the islands

Alcoverro Colom, Pau January 2019 (has links)
No description available.
66

Evaluating the onshore wind power potential of Gotland using the New European Wind Atlas

Arteaga Ossa, Andres January 2021 (has links)
The island of Gotland has played an important role in the history of wind energy in Sweden since the very beginning. In the past decade, the island reached the maximum intermittent wind power capacity that the local grid and the current connection to the mainland can safely manage without compromising the security of supply. There were plans to install a new submarine cable, but they were finally cancelled. Nevertheless, the Swedish Government has decided to start a pilot project to make Gotland the spearhead of the energy transition. Most likely, this means that a new wind power expansion will have to take place on the island. In that context, the present study aims to estimate the onshore wind power potential of Gotland based on the New European Wind Atlas released in 2019. The starting assumption is that the potential of the island is limited to the areas appointed of national interest for wind energy by the Swedish Energy Agency. Then, the wind power potential is estimated under three technological scenarios ranging from the wind turbines operating on the island to the wind turbines recently launched on the global market. The results show that Gotland has the potential to annually produce between 2.2 TWh and 2.7 TWh of additional energy from the available wind depending on the technology used. Comparisons with real production records showed that the wind speed time series from the wind atlas proved to be useful to accurately reproduce the production patterns of real wind turbines on the island when values were aggregated at a daily or higher time scale. Additionally, mean wind speed at 100 m and the parameters of the Weibull functions fitted to the wind speed distributions were mapped for the whole island. Mean wind speeds obtained from the New European Wind Atlas for the areas of national interest on Gotland were compared to the respective values from the Swedish Wind Atlas. It was found that the latter gives systematically higher values with an average difference of 0.4 m/s within the sample.
67

Trendning och tillståndsövervakning av ventilmanöverdon i säkerhetssystem på Forsmark 1 och 2

Schultz, Egil January 2020 (has links)
Nuclear power is one of the main players in the Swedish energy system with close to40% of the electricity production. As nuclear power needs to have a well- functioningsafety system for cooling the reactor and prevent contamination in case of anaccident, the components of this system must be maintained in a functioningcondition.The aim of this report is to find a system for predicting malfunction in the valveactuators in one of the safety systems in Forsmark nuclear plant. This is done byanalysing the curve of the consumed power generated during ordinary valve operationand testing to extract key values. Key values include time of the operation, middlepower, total power, peak value, standard deviation, frequency density between 0 and10 Hz and frequency density between 20 and 30 Hz. These values, in turn, are used intwo methods to identify faults. The first method is classification via machine learningand the second is a calculation of the Mahalaniobis distance.None of these methods proved useful in analysing the most commonly reported faultsin the valve actuators but some evidence suggests that an analysis of the Mahalaniobisdistance can be used to detect faults in the power converter and faults relating towear of the mechanical components.
68

Quenching a rotary cylinder by multiple arrays of water impinging jets

Mir-Mir, Óscar January 2020 (has links)
No description available.
69

An Open Source Energy Modelling Framework Comparison of OSeMOSYS and oemof

Muschner, Christoph January 2020 (has links)
Well-founded research is needed to gain sound insights into the relationship between energy and the environment in order to ensure a basis for responsible policy-making in the face of a climate crisis. Transparency in code and data is a prerequisite for reproducible research in energy modelling and its quality assurance and is embedded in the philosophy of open source energy modelling frameworks (OSEMFs). While the focus was on improving the quality of input data and comparing models to compare results, there has been a lack of research on the effects of the structural assumptions across different frameworks. This thesis analyses the structural differences and structural assumptions between the OSEMFs OSeMOSYS and oemof. The methodology applies a wholly harmonised experimental setup to allocate output differences to diverging contextual assumptions in the underlying different mathematical equations among the OSEMFs. Diverging results between OSEMFs based on different structural assumptions occurred in this thesis and traced back to their origin. OSeMOSYS's and oemof's underlying energy balance equations lead to the same results though, when diverging structural assumptions are removed. Already a single undocumented opaque assumption in the underlying mathematical equations among frameworks can have a noticeable influence on the optimisation results. The documentation of OSEMFs is still not comprehensive enough to facilitate investigations of this kind efficiently, and the documentation of assumptions embedded in OSEMFs’ mathematical equations needs to be more detailed. The thesis could identify opportunities to enhance the performance of OSeMOSYS and highlights the importance of correct framework documentations to ensure their usability in practice. / Välgrundad forskning är fundamentalt för att få en god insikt i förhållandet mellan energi och miljö för att säkerställa en grund för ansvarsfullt beslutsfattande inför diverse klimatkriser. Transparens i kod och data är en förutsättning för reproducerbar forskning inom energimodellering, dess kvalitetssärkring och är inbäddad i filosifin som behandlas av Open Source Energy Modelling Frameworks (OSEMF). Den primära fokusen av rapporten behandlar förbättring av kvaliteten av inmatningsdata och att jämföra resultatet från olika modeller. Det visar sig även finnas forskningsbrister inom effekterna av de strukturella antagagendana i dessa ramverk. Examensarbetet analyserar strukturella skillnader och strukturella antagendan mellan OSEMF, OSeMOSYS och eomof. Metoden tillämpar en harmoniserad experimentell uppsättning för att fördela resultat skillnaderna mellan OSEMF och dess strukturella antaganden. Avvikande resultat mellan OSEMF baserad på olika strukturella antaganden inträffade i denna avhandling och spårades tillbaka till deras ursprung. OSeMOSYS och oemofs underliggande energibalansekvationer leder dock till samma resultat när avvikande strukturella antaganden tas bort. Enstaka odokumenterat osammanhängande antagande i de underliggande matematiska ekvationerna mellan ramarna kan ha ett märkbart inflytande på optimeringsresultaten. Enligt resultat av examensarbetet går det att påstå att dokumentationen av OSEMF ännu inte är tillräckligt omfattande för att underlätta undersökning inom forskningsområdet, samt att dokumentationen av antaganden, vilka är inbäddade i OSEMF:s matematiska ekvationer måste vara mer detaljerade. Denna studie lyckades identifiera möjligheter att förbättra prestandan hos OSeMOSYS samt poängterar vikten av korrekta ramdokumentation för att säkerställa programmets användbarhet i praktiken.
70

Mobility-as-a-Service and Electrification of Transport : A Study on Possibilities and Obstacles for Mobility-as-a-Service in Stockholm and Implications for Electrification of Vehicles / Mobility-as-a-Service och Elektrifiering av Transport : En Studie av Möjligheter och Hinder för Mobility-as-a-Service i Stockholm ochImplikationer för Elektrifiering av Fordon

Petersson, Albert January 2020 (has links)
Increasing urbanization drives the need for cities to make transport more efficient, both to meet climate goals as well as creating an attractive living environment for its residents, with less congestion, noise and local pollution. As vehicles are increasingly electrified, further innovations will be needed in order to meet environmental, social and economic sustainability targets, and a more efficient use of vehicles and public transport is central in this endeavor. As new generations are increasingly multimodal and digitalization opens up for innovative concepts, the possibilities for innovations to meet these challenges increases. Against this backdrop, Mobility as a Service (MaaS) has emerged as a concept with the potential to increase sustainability and mobility in cities. MaaS is based on the goal to challenge private car ownership by gathering different mobility services in one application, thereby creating a service offering with the potential to be more attractive than car-ownership. However, many varieties of MaaS exists and intensive efforts are ongoing to understand how MaaS can work in practice. MaaS has been described as a phenomenon with potential to radically change how people move in the future. The purpose of this thesis has been to understand how MaaS can affect the electrification of sustainable cities, with a focus on e-mobility. Starting off by trying to understand barriers to increased car-sharing in Stockholm, possibilities and challenges for MaaS in the city is discussed and its potential effects on emobility there. Data has been collected through continuous evaluation and review of literature and conducted interviews with actors and stakeholders within traffic and sustainable mobility in Stockholm. The results have been analyzed from a sustainable innovation perspective to discuss opportunities and challenges for the development of MaaS and its impact on electrification of vehicles. Collected empirics indicate that Stockholm has good opportunities for facilitating MaaS in the future, mainly due to accessible and extensive public transport (PT). The success of MaaS largely depends on the understanding of the service among consumers and why increased attention and marketing is important. An actor’s logic in individually owning the customer contact to be able to improve a service offering can be an obstacle to the growth of future mobility platforms. This underlines the need for cooperation between involved players to create momentum for MaaS. At the same time, MaaS benefits from a wide range of underlying mobility services and progressive traffic planning. In this regard, the results indicate that there are a number of different instruments at a macro level that could facilitate the sharing services to be developed. A legal definition of car sharing is a first step to facilitate measures to stimulate MaaS. Measures that smooth the relationship between the private car and car sharing services can create momentum for these, for example through exemptions from congestion tax. Access to parking at reasonable costs appears to be a key enabler for flexible shared mobility services in the future, partly because it currently accounts for a large part of the costs, and partly because the degree of flexibility and accessibility is determined by access to parking. At the same time, tougher parking regulations for BRFs and companies have also created a market for mobility services. Long term, there is a consensus that the future of transport is electrified. However, the impact of shared services and MaaS is highly shaped by the technical development of vehicles. Ongoing electrification of vehicles highlights the need for charging infrastructure deployed at locations that fits the need of shared services. Also, the charging equipment and solutions has to be developed to fit the needs of shared services and have a shared customer in mind. / Urbanisering ökar behovet för städer att effektivisera sina transportsystem, dels för att möta klimatmål och dels för att skapa en attraktiv stadsmiljö för sina invånare med mindre trängsel, föroreningar och buller. Elektrifiering av fordonsflottan för att minska utsläpp påverkar redan idag transportsektorn i hög grad, men samtidigt krävs ytterligare åtgärder för att möta ekonomiska, miljömässiga och sociala hållbarhetsmål, där ett effektivare utnyttjande av fordonsflottan och kollektivtrafiken är centralt. Yngre generationers förändrade resvanor och digitaliseringens utveckling ökar möjligheterna för innovativa modeller som kan möta dessa behov. Mot denna bakgrund har Mobility as a Service (MaaS) utvecklats som ett koncept med potential att förbättra hållbarhet och utöka mobiliteten i städer. MaaS bygger på att utmana det privata bil-ägandet genom att samla olika mobilitetslösningar i en plattformstjänst, för att skapa ett serviceerbjudande till en användare med potentialen att vara mer attraktivt än en bil. Emellertid finns flertalet olika varianter av MaaS och det pågår intensivt arbete och forskning för att förstå hur MaaS kan fungera i praktiken. Denna studie har utgått från syftet att förstå hur MaaS kan utvecklas och påverka framtidens hållbara städer, med fokus på e-mobility. Med utgångspunkt i att försöka förstå barriärer för bildelningstjänster i Stockholm, diskuteras möjligheter och hinder för MaaS i samma stad och dess eventuella effekter på e-mobility där. Underlag har samlats in genom en litteraturstudie och genom intervjuer med aktörer inom trafik och hållbar mobilitet i Stockholm. En extern workshop i ämnet med inblandade aktörer i Stockholm har också besökts under arbetets gång. Resultaten har analyserats från ett hållbart utvecklings - perspektiv för att kunna diskutera möjligheter och hinder för MaaS framväxt och dess påverkan på elektrifiering av fordon. Underlaget visar att Stockholm har goda möjligheter för framväxt av MaaS framöver, framförallt beroende på en tillgänglig och utbyggd kollektivtrafik. Framgången för MaaS till stor del beror på förståelsen för tjänsten bland konsumenter, varför ökad medvetenhet och marknadsföring generellt är viktigt. Aktörers vilja att enskilt äga kundkontakten för att kunna förbättra ett serviceerbjudande kan vara ett hinder för en framväxt av framtida mobilitetsplattformar och understryker behovet av ett kooperativt samarbete mellan inblandade aktörer för att skapa medvind för MaaS. MaaS gynnas samtidigt av ett stort utbud av underliggande mobilitetsttjänster och progressiv trafikplanering. I detta avseende indikerar resultaten att det finns ett antal olika styrmedel på en makro-nivå som skulle kunna underlätta för delningstjänster att utvecklas. En juridisk definition av bildelning är ett första steg för att underlätta åtgärder för att stimulera delad mobilitet och MaaS. Åtgärder som jämnar ut förhållandet mellan den privata bilen och bildelningstjänster kan skapa medvind för dessa, exempelvis genom undantag från trängselskatt. Tillgång till parkering till rimliga kostnader framträder som en central möjliggörare för flexibla delade mobilitetstjänster i framtiden, dels eftersom det i nuläget står för en stor del av kostnaderna, dels eftersom graden av flexibilitet och tillgänglighet bestäms av tillgång till parkering. Samtidigt har hårdare parkeringsregleringar för BRF: er och företag också skapat en marknad för mobilitetstjänster. På längre sikt framstår det en konsensus kring att framtiden för transporter är elektrifierad, men att MaaS och delade mobilitetstjänsters påverkan på elektrifierade transporter i hög grad avgörs av den tekniska utvecklingen hos fordon. Elektrifiering av fordonsflottan understryker behovet av laddinfrastruktur utformad efter delningstjänster, både geografiskt men även genom att utrustning för laddning är utformad med en delad bil i åtanke.

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