Vindkraften expanderar allt mer i Sverige och årsproduktionen ökade till 6,1 TWh år 2011, vilket är en ökning med 74 % jämfört med 2010. De nya vindkraftverken som sätts upp idag är oftast av effektstorlekarna 2 000 – 3 000 kW. De som restes tidigare är omkring 200 – 600 kW. I Sverige finns det många vindkraftverk som har varit i drift under en längre tid, och det är flera som passerat sin tekniska livslängd på 20 år. De första vindkraftverken som man reste står ofta på platser med väldigt goda vindförhållanden och har väldigt låga effekter, om man jämför med dagens vindkraftverk. Det börjar därför bli högaktuellt att demontera äldre befintliga verk och resa nya. Detta kallas för vindkraftens generationsskifte, kanske mer känt som repowering. Tyskland, Danmark och Nederländerna är länder som redan har bytt ut stora delar av sina vindkraftsflottor. Danmark är världsledande inom repowering och har bytt ut omkring två tredjedelar av sina äldre verk. I många av de projekt som genomförts har en dubblering och ibland till och med en fyrdubblering av energinmängden skett! Genom att resa nya verk blir det oftast färre verk på platsen, samtidigt som mer energi levereras. På så sätt utnyttjas platsen på ett bättre sätt, vindkraftselen blir billigare. Det blir samtidigt enklare att uppnå politiska riktlinjer med mål inom förnybar energi och många anser att landskapsbilden förbättras. Detta examensarbete genomfördes i syfte att undersöka möjligheterna och lönsamheten för generationsskiften i Hallands län. För att veta vart de olika vindkraftverken är placerade i Halland genomfördes en kartläggning och identifiering initialt. När verken var kartlagda gjordes projekteringar av nya parker. Det visade sig vara ont om plats att resa de nya verken, eftersom de är högre än de gamla och kräver längre avstånd till bostäder. Därför genomfördes inte enbart projektering av parker där befintliga vindkraftverk står utan även på helt nya områden som idag inte har någon vindkraft. I varje projekt utfördes ekonomiska beräkningar som grundar sig på energiberäkningarna från projekteringen i vindatlasprogrammet WindPRO. Arbetet har också behandlat hur och om ersättning till ägare av befintliga verk och markägare kan ske, samt vad alternativen är för de befintliga vindkraftverken vid ett generationsskifte. Projektgruppen har varit i kontakt med vindkraftsägare och ställt frågor om hur de ställer sig till ett generationsskifte. Det främsta resultatet som projektgruppen kommit fram till är att generationsskiften absolut har goda möjligheter till att bli lönsamma. Det kan dock bli problematiskt att få plats med nya vindkraftverk på områden där gamla verk står. Det beror på kommunens regler om avstånd till närboende, och att ett visst antal verk måste resas vid nybyggnation. Ändras dessa regler för generationsskiften, blir möjligheterna väldigt goda. Vad det gäller efterhandsvärde på de gamla verken är slutsatsen, att det går att göra en bra affär genom att sälja sitt verk. Vid skrotning däremot blir intäkterna från försäljning av metallerna för små för att täcka demonteringskostnaden. Generellt sett har vindkraftsägarna en positiv syn till ett generationsskifte. / The installations of wind turbines are expanding rapidly each day in Sweden and 2011 wind energy generated 6,1 TWh. This is an increase with 74 % compared to 2010. The modern wind turbine that becomes integrated in the Swedish electricity grid at the moment often has a power capacity of 2000-3000 kW. Many of those wind turbines which are already integrated in the grid soon need to be replaced. These turbines often have a power capacity of 200-600 kW. Many of these old turbines have been generating electricity for almost 20 year, which is the technical lifetime for a wind turbine. These old turbines are also often located on sites with great energy levels. This makes it interesting to investigate the possibilities and if there is a profit in repowering. Repowering is when you dismantle old turbines and replace them with new ones. Germany, Denmark and the Netherlands are countries in Europe, which have already been doing repowering for some time. Denmark is the country where most repowering has been done. They have exchanged two thirds of their old turbines. In most of the projects which has been done, the energy level has been doubled and in some cases even quadrupled! When the modern larger turbines replace the old smaller ones, fewer turbines are raised on the site although the energy level increases. While doing repowering the sites are used in a better way, it makes the electricity prices cheaper, the political ambitions in renewable energy are easier reached and many people also claim, that the landscape is improved. This bachelor´s thesis has the objective to investigate the possibilities and the profit for future repowering projects in county of Halland, Sweden. To find out where the wind turbines are located in the county, mapping and identification where done. When the mapping was done, projections of new parks where created. It turned out that these old turbines often where located on a very limited area, which makes it hard to establish new larger turbines. This is because they need larger distance to the nearest residences. Because of this, projections also where done on other locations. In every project economical calculations were made, which are based on the energy results from the projections, which were made in WindPRO. The thesis has investigated how and if the owner of the old wind turbines and the land holder can be compensated when repowering. Researching and brainstorming on different scenarios for what will happen to the old turbines has also been done. We have had contact with owners of wind turbines to find out, what their opinion are about repowering. The prime conclusion from this bachelor thesis is that repowering has good possibilities to be profitable. There might be some problems to project new wind turbines on the same site where the old turbines where located, if the municipality don’t change the distance demands to residences and the demand that a group of wind turbines must be raised. If these demands are changed, the future for repowering looks very promising. Another conclusion where that there might be good profit in selling the used wind turbine, but to sell the used material of a wind turbine to recycling is not profitable. Profit from selling the turbine material to recycling does not cover the cost for dismantling it. Owners of the wind turbines have in general a positive attitude to repowering.

Many reasons to consider extending the useful time of ageing wind farms. Like to take advantage of it being located in a good wind source, besides existing infrastructure, etc. Repowering can be an appropriate option for the ageing wind farm that suffering less yield energy and increment of cost of operation and maintenance.  The thesis discusses the repowering potential of old wind farms. The case study is implemented on a selected wind farm in Denmark. Different repowering scenarios were considered with the technical-economic assessment for each scenario to determine which scenario is viable. The sensitivity analysis was done taking into consideration selected parameters to find out the effect of each parameter on the profitability and productivity of the repowered wind farm. More details will be explored in the following chapters.

Germany is one of the pioneer countries in wind turbine technology. They installed many wind turbines during the last decades and are now confronted with a shortage of land suitable for new wind parks. Now, with an estimated wind turbine service life of 20 – 25 years whole wind parks are becoming obsolete and owners have to decide whether do decommission, repower or to continue the operation of their parks. The advantages of repowering as well as the bureaucratic hurdles are outlined and evaluated. This thesis deals with the repowering potential in North Rhine-Westphalia and is analysing the technical and economical possibilities of repowering. The main objectives are to identify wind turbines eligible for repowering and also to develop repowering scenarios in order to determine their techno-economic feasibility.  The designed steps of the methodology allow the census and the subsequent implementation of the results in WindPro and RETScreen.

There is a need for an efficient adjustment of the energy supply system towards renewable energy resources in the near future. This raises the question whether it is financially efficient to repower an onshore wind turbine or wind farm in operation with respect to specific surrounding conditions? To this purpose, the objective of this Thesis is a quantitative analysis of a wind power project repowering addressing certain legislative parameters, varying economic factors and WT models respectively. To enable this analysis, a case-study considering a number of hypothetical scenarios for repowering a wind farm in Germany has been applied. The scenarios address in particular the widely implemented limitation in overall building heights of 100m depending upon varying economical parameters. Nevertheless, this case-study applies three different WT models whereof one model matches the legislations and the other two models exceed the legislations by a varying degree in order to evaluate a potential productivity growth. The varying economic conditions are represented by a base case projection applying average wind power construction costs and financial rates whereas a best case and worst case projection consider deviating interest rates, capacity factors, investment and O&M costs respectively.   The economic calculations together with the determination of the capacity factor with respect to each WT model are performed by utilising the decision aid tool RETScreen. The results obtained by this case-study show versatile economic and technological performance. WT models of minor size addressing in particular local existing legislation regarding the limitation of overall height which must not exceed 100m are inefficient regardless of varying economic conditions. Exceeding the limitation, WT models provide a significant increase in performance and thus return positive economic results independent of varying economic conditions. The main conclusion is that existing local legislations based on previous considerations from the past but which no longer correspond to the state of technology have to be questioned in general or have to be mitigated by subsidy instruments in order to support a generation shift in technology before the end of life of operational wind farms and thus promptly increase efficiency by repowering.

Orientador: Prof. Dr.Antônio Garrido Gallego / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2017. / Atentando-se à diversificação da matriz energética, expansão da oferta de energia e a aproximação do fim da vida útil de usinas nucleares, como Angra I, planejado para 2025, este trabalho apresenta um estudo de repotenciação de usinas nucleares PWR (Pressurized Water Reactor). A estratégia de repotenciação utilizada baseou-se na combinação da usina nuclear com turbinas a gás, compondo um arranjo similar aos ciclos combinados tradicionais, mas que utiliza energia nuclear e do gás natural paralelamente. A conexão entre as duas fontes ocorre por meio de caldeiras de recuperação, que utilizam os gases de exaustão das turbinas a gás para geração de vapor, que é utilizado na usina nuclear, o que possibilita a redução da potência térmica do reator. Efetuaram-se análises de energia nos ciclos propostos e constatou-se que os ciclos podem atingir eficiências energéticas entre 44% e 46%, no caso de ciclos que ultrapassam a potência nominal da antiga usina nuclear, e eficiências energéticas por volta de 39% no caso de ciclos com potência limitada à da antiga usina nuclear. Também foi possível avaliar qualitativamente as configurações que exigiriam menores modificações na usina nuclear. Foi realizada análise econômica onde estimou-se o custo de geração de energia elétrica dos ciclos propostos, obtendo 69,5 US$/MWh, que foi menor que o custo de uma nova usina a gás natural (80,8 US$/MWh) e uma nova usina nuclear (110,9 US$/MWh). Entretanto, os ciclos de repotenciação apresentaram custo de energia maior do que a possibilidade de extensão da vida útil de usinas nucleares por meio de investimentos em trocas de equipamentos e programas de manutenção (36,2 US$/MWh - Extensão das operações LTO ¿ do inglês: Long Term Operation). / Considering the diversification of the energy matrix, expansion of the energy supply and the approximation of the end of life of nuclear power plants, such as Angra I, planned for 2025, this work presents a repowering study of PWR (Pressurized Water Reactor). The repowering strategy was based on combination of the nuclear power plant with gas turbines, composing an arrangement like traditional combined cycles, but utilizing nuclear and natural gas in parallel. The connection between the two sources occurs through recovery boilers, which use the exhaust gases from gas turbines for steam generation, which is used in the nuclear power plant, which allows the reduction of the reactor thermal power. Energy analyzes were carried out in the proposed cycles and it was found that the cycles can achieve energy efficiencies between 44% and 46% in the case of cycles exceeding the nominal power of the former nuclear power plant, and energy efficiencies around 39% in the case of cycles with power limited to that of the old nuclear power plant. It was also possible to qualitatively evaluate the configurations that would require minor modifications at the nuclear power plant. An economic analysis was carried out to estimate the cost of generating electricity from the proposed cycles, obtaining 69.5 US$/MWh, which was lower than the cost of a new natural gas plant (80.8 US$/MWh) and a new nuclear power plant (110.9 US$/MWh). However, the repowering cycles had a higher energy cost than the possibility of extending the life of nuclear power plants through investments in equipment exchanges and maintenance programs (36.2 US$/MWh, LTO - Long Term Operation).

Wind power is a fast-growing industry (GWEC, 2013) and already accounts for seven percent of the total electricity consumption in the EU. The largest market in the EU, and the third largest in the world, is Germany, with an installed base of 31 GW onshore. This master‟s thesis has examined the German onshore wind power market from a developer perspective, through a market study based on existing literature and semi-structured interviews with industry experts, a case study of a developer competing in the market and a survey, with the aim of investigating the sourcing models used as well as the success factors and challenges the developers are facing.  The study has found that Germany is a large, growing market with a generous feed-in tariff based support scheme, offering low-risk investments in wind power. However, there are many challenges for wind power developers, such as limited availability of designated areas for wind power development, non-uniform regulations, fierce competition and acceptance issues.  The authors believe that the future growth of the German onshore market will come from repowering and that having local contacts and credibility offer distinct advantages in the highly competitive arena.

In the southern part of Sweden, specifically in price zone SE4, there is an increasing cost of electricity and a contemporary supply deficit. This research aims to elaborate on the deficit in electrical generation to consumption in SE4. The found values indicate a 42% unmet demand, equaling 5.152 TWh annually. However, long-term solutions on a European and Swedish regional level require years to be implemented, and the complications of permitting and public acceptance of new renewable projects pose a delaying factor. Henceforth, repowering aging wind farms, which are nearing the end of their operational lifetime, presents a viable solution. In this research, a case study for SE4 old wind sites has been identified and assessed, using three repowering scenarios: Scenario I - wind, Scenario II - wind & solar, and Scenario III - wind, solar & storage system. The scenarios have been simulated using the available renewable resources in the case study area and retrofitted within the exact required surface area that the current case study system occupies of 42.71 km2. The results have shown that all scenarios have great potential to limit the 42% deficit of supply in SE4 when implemented. The share of annual generation found for each scenario was 0.939 TWh, 3.08 TWh, and 3.962 TWh, respectively. These annual generations will contribute to 7.7%, 25.32%, and 32.5% of the annual electrical consumption found for SE4. The first scenario of only wind energy is the most economical and has the highest capacity to productiveness of area ratio, at a 22.27 GWh/km2/year for 68 MW installed capacity.

The Florida manatee (Trichechus manatus latirostris), a subspecies of the West Indian manatee, is one of the most endangered marine mammals in United States waters. The Florida manatee is the only manatee that ranges into subtropical and temperate regions. During the winter months manatees adopt a “refuging strategy” where they aggregate at warm-water sources immediately following decreases in the ambient water temperature to below 20° C (68° F) in order to avoid cold stress syndrome (CSS). During the winter manatees aggregate in warm water refuges, including natural warm water springs and the effluent discharges of power plants. The purpose of this study was to determine the number of manatees that aggregate and utilize the waters of the Florida Power and Light (FPL) Plant in Port Everglades (PPE), Florida, its effluent canal, and the surrounding Intracoastal Waterway during the winter months. This study documents the importance of Port Everglades as a wintering refuge for the Florida manatee. This study analyzed the inverse relationship between the number of manatees present at a warm water effluent and water temperature. In this study data were collected over five manatee winter seasons (between 15 November and 31 March) from 1999-2004, from both boat-based and land-based surveys monitoring the presence of manatees in the effluent canal from the FPL electricity generating facility in Port Everglades, FL and the Intracoastal Waterway. Findings indicated that there was an inverse relationship between the number of manatees present and water temperature, where more manatees were present in cooler months, and fewer in warmer months. This study also analyzed the parameters of Catch per Unit Effort (CPUE) as well as heating degree-days and their effect on and relationship to the number of manatees present. The higher the heating degree-days number, the more severe, or cold, winter this indicates. The year with the highest heating degree-days, 24.98, was the 2002-2003 season, which was also the season with the highest number of manatees observed, 393, and the highest CPUE, 10.62 manatees/day.

Transitioning to a low-carbon energy system includes deploying renewables such as wind power, which has been installed in Sweden since the 1980s. After a 20 to 25-year lifetime, a wind turbine´s end-of-life options come into play, therefore many of the turbines deployed in Sweden prior to 2011 will reach this mark by 2035. To utilize a site´s wind resource in the best possible way, full repowering is considered in an assessment of seven case studies in Swedish municipalities with the highest deployed pre-2011 wind power capacity. Each case study uses various turbine models to evaluate full repowering scenarios. The most profitable scenarios are estimated through the investment over production (I/P) value and the break-even electricity price. The identified municipalities’ comprehensive plans are reviewed in terms of repowering strategies and wind power deployment guidelines. Only three out of seven investigated municipalities consider repowering in comprehensive plans, with Gotland being best prepared in terms of repowering strategies. Strömsund and Eslöv mention repowering in their comprehensive plans with no specific guidelines. Restrictive policies were identified in the municipality of Laholm, where the maximum total height of turbines is 150m, decreasing the potential annual energy production of an analyzed case study by 64%. The municipalities of Falkenberg, Laholm, Piteå, and Åsele do not include repowering in their comprehensive plans. All the simulated repowering scenarios increased the annual energy production of the identified sites by up to 73%, lowered the number of turbines by up to 70%, decreased the wake losses by up to 77%, and decreased the noise level by 10% while increasing the potential shadow flicker by 19%. The results of the study indicate a possible divide between the intention of the municipalities of Eslöv, Strömsund, and Åsele to maximize energy production from wind power at each exploited site on the one hand and the business cases that developers face on the other. The results suggest the turbines which increase energy production the most at already developed sites, are not necessarily the ones with the lowest investment over production (I/P) value or the lowest break-even electricity price.

Como parte de um projeto de pesquisa e desenvolvimento (P&D) mais amplo, que está sendo desenvolvido pela Escola de Engenharia de São Carlos - USP e Companhia Paulista de Força Luz (CPFL), com previsão de conclusão para 2010, este trabalho tem por objetivo apresentar os principais procedimentos para a realização da repotenciação de linhas de subtransmissão de 34,5 KV para 69 KV. Para atingir esse objetivo, é realizada inicialmente uma apreciação do estágio atual dos estudos sobre o tema, abordando inclusive outros métodos além daquele que será objeto específico desse estudo. Em seguida, discutem-se tópicos relevantes dos métodos apresentados de forma que, esse estudo, além de cumprir o já mencionado objetivo específico de apresentar soluções para aumentar a capacidade de transmissão de uma determinada linha, mantendo a sua faixa de servidão, indicará parâmetros válidos para a realização de outros projetos da mesma natureza. Sequencialmente são apresentadas as etapas desenvolvidas para a operacionalização da repotenciação de uma linha, a começar pela escolha da mais adequada, a seleção do método a ser utilizado, levando-se em consideração tanto a alteração do limite térmico da linha quanto à elevação de sua tensão operativa e os aspectos ambientais que envolvem a repotenciação. Finalmente, fazendo uso dos softwares ATP, através da interface gráfica ATPDraw (empregado para as XIV simulações de transitórios eletromagnéticos) e do Flux®, para as simulações dos campos elétricos em torno dos isoladores, realizou-se um conjunto de simulações computacionais pertinentes para um bom conhecimento do funcionamento da linha de subtransmissão a ser repotenciada na classe de interesse. Todas as etapas e as conclusões preliminares sobre o assunto delineado serão apresentadas neste documento. / As part of a wider research and development project, which is being developed between Escola de Engenharia de São Paulo USP and Companhia Paulista de Força e Luz (CPFL), scheduled to be finished in 2010, this work aims to present the main procedures to perform a repowering on subtransmission lines from 34.5 KV to 69 KV. To achieve this purpose, an assessment of the current studies about the subject is carried out, including an approach of other methods besides the one which is going to be the specific object of this study. After this, relevant points about the main methods are discussed in such a way that this study, in addition to serve its specific purpose, that is to present solutions in order to increase the transmission capacity of a determined line, keeping its right-of-way, can also point out valuable parameters which can be used to develop other projects of similar nature. Sequentially, the steps followed to operationalize the line repowering are presented, starting with the choice of the most suitable line, the selection of the method to be used, and taking into consideration both the change in the line thermal limit and the elevation on its operating voltage and also the environmental aspects involving repowering. At last, making use of ATP software throughout ATPDraw graphical interface (which is used to simulate electromagnetic transients) and Flux®, that simulates electrical fields around insulators, it is carried out a set of computational XVI simulations which are relevant to a good knowledge of the line subtransmission running. All the steps and preliminary conclusions about the subject are going to be outlined on this document.