This paper presents an analysis of the feasibility of utilizing a hybrid renewable energy system to supply the energy demand of a milk and meat farm in Cuba. The study performs simulation and optimization to obtain a system design of a hybrid renewable energy system for application on the farm Desembarco del Granma in the Villa Clara province in the central part of Cuba, for three different cases of biomass availability. The energy resources considered are solar PV, biogas, and wind. A field study is carried out to evaluate the energy load and the biomass resource available for biogas production of the farm Desembarco del Granma, and the feasibility of biogas electrification is evaluated for the three different scenarios of biomass availability. The field study methodology includes semi structured interviews and participant observation for information collection. The farm Desembrero del Granma is estimated to have a scaled annual average electrical load of 264 kWh/day with peak load 26.34 kW, while the scaled annual average deferrable load of the farm was estimated to be 76 kWh/day with a peak load 16 kW. The thermal load was find to consist primarily of energy for water heating and cooking. The thermal demand for cooking was estimate to be 4.5 kWh per day, while the thermal load for water heating was not estimated. The thermal energy need for water heating is assumed to be provided for by solar thermal energy, and is not included in the energy system models of this study. For the modeling, the thermal demand for cooking is assumed to be provided by combustion of biogas. System simulation and optimization in regard to energy efficiency, economic viability and environmental impact is carried out by applying the Hybrid Optimization Model for Electric Renewables (HOMER) simulation and optimization software tool. For two of the biomass scenarios, the optimized energy systems received in HOMER were identical; hence only two biomass scenarios were analyzed. The first one represents the current biomass collected and the biogas production capacity of the farm (including the one not yet utilized), and the second one represents the amount of biomass available if the animals would be gathered in the same place all of the time. A PV-wind hybrid energy system with 100 kW PV installed capacity, 30 kW wind power installed capacity consisting of 10 wind turbines of the size 3 kW, a battery bank of 100 batteries (83.4 Ah/24 V), and a 100 kW inverter is considered the most feasible solution for the current biomass scenario. For the increased biomass scenario, a PV-biogas hybrid energy system configuration of 5 kW PV installed capacity, a 60 kW biogas generator, and an inverter of the size 10 kW is considered the most feasible option. Biogas electrification is shown to not be economically feasible for the current biomass scenario during the conditions modeled in this study, but for the increased biomass scenario biogas electrification was shown to be a feasible option. If the farm would build more biodigestors, biogas electrification could thereby be effective from a financial point of view.

The challenge of managing the present and projected electricity energy needs along with targets of mitigating CO2 emissions leads to the need for energy systems to reduce reliance on fossil fuels and rely on more energy from renewable sources. The integration of more renewable energy technologies to meet present and future electricity demand leads to more challenges in matching the trade-o between economic, resilient, reliable and environmentally friendly solutions. Energy storage technologies can provide temporal resilience to energy systems by solving these challenges. Energy storage systems can improve the reliability of energy systems by reducing the mismatch between supply and demand due to the intermittency of renewable energy sources. This thesis presents a comprehensive analysis of various energy storage systems, analyzing their speci c characteristics including capital cost, e ciency, lifetime and their usefulness in di erent applications. Di erent hybrid energy systems are designed to analyze the impacts of renewable and non-renewable energy sources and energy storage systems in residential on-grid and o -grid buildings and districts. An optimization analysis is performed to determine which technology combinations provide the most economic solution to meet electric energy demands. The optimization analysis is solved using the "energy hub" model formulation which optimizes energy system operation and capacity of di erent technologies. Di erent energy systems can be optimized by using energy hub model, including multiple input energy carriers that are converted to multiple energy outputs. The analysis in this thesis employs a building simulation tool to model residential building, and real data sets to explore the di erent electricity pro le e ects on the results. The environmental e ect of hybrid energy systems comparing with base cases of conventional energy systems or grid connection are also analyzed. Results show that the feasibility of energy storage systems is a factor of di erent variables including capital cost of energy converters and energy storage systems, cost of input streams (grid electricity in on-grid systems and diesel fuel in o -grid systems, energy demand pro les and availability of renewable energy sources. The on-grid single and district buildings do not select storage technologies at current costs due to cheap grid electricity. Reduction in the cost of renewable energy technologies and/or energy storage systems (e.g. Li-ion batteries) results in more energy storage installations. In o -grid systems (single buildings and districts), Li-ion battery and pumped hydro are the main storage systems that can balance the daily and seasonal energy demands. / Graduate / 2021-03-13

Wind power can be related to natural disasters in several ways. This licentiate thesis gives some background and introduces four papers devoted to two aspects of this relation. The first section looks into how small-scale wind energy converters (WECs) could be used to generate power after a natural disaster. For this application diesel generators are the most common solution today, but there would be several advantages of replacing these systems. A study of off-grid systems with battery storage at 32 sites showed that photovoltaics (PV) were more suitable than WECs. The results were confirmed by a study for the entire globe; PV outperformed WECs at most sites when it comes to small-scale application. This is especially true for areas with a high disaster risk. Hybrid systems comprising both PV and WECs are however interesting at higher latitudes. For the Swedish case, it is shown that gridded data from a freely available meteorological model, combined with a statistical model, give good estimates of the mean wind speed at 10 meters above ground. This methodology of estimating the mean wind speed can be used when there is no time for a proper wind measurement campaign. The second section is directed towards wind power variability and integration. The results presented in the thesis are intended as a basis for future studies on how a substantially increased wind power capacity affects the electric grid in terms of stability, grid reinforcement requirements, increased balancing needs etc. A review of variability and forecastability for non-dispatchable renewable energy sources was performed together with researchers from the solar, wave and tidal power fields. Although a lot of research is conducted in these areas, it was concluded that more studies on combinations of the sources would be desirable. The disciplines could also learn from each other and benefit from the use of more unified methods and metrics. A model of aggregated hourly wind power production has finally been developed. The model is based on reanalysis data from a meteorological model and detailed information on Swedish WECs. The model proved very successful, both in terms of low prediction errors and in the match of probability density function for power and step changes of power. / Vindkraft kan relateras till naturkatastrofer på flera olika sätt. Den här licentiat\-avhandlingen ger bakgrund till och introducerar fyra artiklar som beskriver två aspekter av detta samband. I den första avdelningen undersöks hur småskalig vindkraft skulle kunna användas för att generera el efter en naturkatastrof. I dagsläget är det dieselaggregat som används för detta ändamål, men det skulle finnas stora fördelar med att övergå till förnybara system. En studie av 32 platser (myndigheten MSB:s utlandsstationeringar augusti 2012) visade att solceller var mer lämpade än vindkraftverk. Resultaten bekräftades av en studie för hela världen; solceller ger billigare system än småskaliga vindkraftverk för de flesta platser, inte minst om man tittar på områden som är utsatta för naturkatastrofer. Hybridsystem med både solceller och vindkraftverk var dock intressanta på högre breddgrader. För Sverige så visas det att data från en fritt tillgängliga meteorologisk modell tillsammans med en statistisk korrigering beroende på terrängtyp ger bra uppskattningar av medelvinden på 10 meters höjd. Den föreslagna metodiken kan vara användbar som ett komplement till vindmätningar eller om det inte finns tid eller möjlighet till en riktig mätkampanj. Den andra avdelningen är inriktad mot vindens variabilitet och integrering av vindkraft i kraftsystemet. De resultat som presenteras i denna avhandling är tänkta som en bas för framtida studier av hur en kraftigt ökad andel vindkraft påverkar elsystemet med avseende på stabilitet, nödvändiga nätförstärkningar, ökade krav på balanskraft etc. En översiktsstudie av variabilitet och prognosbarhet för intermittenta förnybara energikällor gjordes tillsammans med forskare inom sol-, våg och tidvattenkraft. Även om mycket forskning pågår inom dessa områden så var en slutsats att mer studier för kombinationer av olika källor skulle vara önskvärt. Forskare inom de olika disciplinerna skulle också kunna lära från varandra och dra fördel av gemensamma metoder och mått. Slutligen har en modell av aggregerad timvis vindkraftproduktion tagits fram. Modellen baseras på data från en meteorologisk modell samt detaljerad information om vindkraftverk i Sverige. Modellen visade sig vara mycket träffsäker, både vad gäller låga prediktionsfel och i överensstämmelse av sannolikhetsfördelning av effekt och stegförändring av timvis effekt.

The aim of this thesis study is to design a hybrid energy system comprised of wind turbines, diesel generators and batteries to provide electricity for an off - grid rural community in Kenya. Wind Measurements collected over six years from 12 locations in Kenya have been studied and one site selected for this project due to its wind potential, geographical location and socio-economic potential. The energy system is designed to cater for the electricity demand of 500 households, one school, one medical clinic and an irrigation system. The system will support up to 3000 people. The Hybrid Optimization Model for Electric Renewables (HOMER) is the software tool that has been used to simulate the hybrid system and analyze its results. The optimization has been carried out and presented according to cost of electricity and sensitivity graphs have been used demonstrate the optimization based on diesel price and wind turbine hub height.

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The rise in population causes serious issues in larger cities since the electrical grid is becoming overloaded. Simultaneously, the demand on more sustainable energy production and the use of renewable energy sources increase. Renewable energy based off-grid electrical systems are a possible solution to decrease the magnitude of these issues. The purpose of this thesis is to compare solar cells, solar thermal collectors and PVT (Photovoltaic thermal hybrid solar collectors) and design the most suitable combination of solar panels for a selfsufficient multi-family house in Jönköping, Sweden. The solar panels were compared from a cost and energy production perspective, then a suitable renewable energy system with all three types of panels was constructed and optimized using Opti-CE, which is a MATLABbased software. During the course of this thesis, an interview was made with Hans-Olof Nilsson who is a co-founder of Nilsson Energy and owner of a self-sufficient off-grid house. The results show that PVT-panels have higher energy production per area and 22% higher LCC (life cycle cost) than regular solar cells in combination with solar thermal collectors. Optimization results indicate that the house cannot be self-sufficient by installing solar panels on the given roof area only, rather the area of installed solar collectors should be increased to a minimum of 1497𝑚2 . With the given roof area of 900𝑚2 the house can only be self-sufficient a maximum of 75% of the time. The results also indicate that the introduction of compact systems with the simultaneous decrease of cost will make renewable off-grid energy systems more attractive in the future.

The increasing popularity and improvements in the blockchain technology that offers decentralized communication and transactions in the form of cryptocurrencies that have now days a market value of almost 1.3 Trillion dollars and a huge potential to contribute to other fields such as health care, financial transactions, information technology, secure data exchange, data storage and many others has been pushing towards more integrating of renewable energies in this field. The process of approving and inserting the information and contracts with Bitcoins on the blockchain is called mining of Bitcoin and accounts for a large electricity consumption which has been estimated to be around 120 Terawatt_hour (TWH) worldwide in 2023. To keep this field of technology improving and strengthen its development, leading it towards more usage of clean energy will benefit the field and most importantly will help our societies to face climate change and align with the United Nations sustainable goals regarding integrating and increasing the usage of renewable energies and sustainable methods in all fields of life and industry.  The purpose of this study is to assess the feasibility of building a mining farm for bitcoin powered by renewable energies, solar and wind, by using photovoltaics systems and wind turbines with the integration of storage mediums to utilize the clean energy as much as possible. The project is done by firstly conducting a literature review about the technologies used followed by choosing the most appropriate alternatives that fit best for the current project properties and goals. After choosing the components and methods to be used , the technical feasibility is analyzed by simulating the hybrid energy system using a code program written in the software MATLAB which optimizes and calculates on one hand the electricity production of the system that is used for the hourly reliability in meeting the load demand of the mining devices and on the other hand the total cost of the system which will be built upon to estimate the levelized cost of energy and hence analyze the economic feasibility of the project.After conducting the simulation and financial calculations, the results show that the project is technically feasible and the reliability can be as high as around 8650 hours of the year, however, to achieve a 100 percent reliability a support power should be used such as a diesel generator which has also been done in this work. The economic feasibility indicates that the project will be profitable based on the installed capacities and mined Bitcoins, however a storage medium and a support power production source are vital for the success of such a project.

Due to the result of the sudden fossil fuels over-night price rises of 1973/1974, coupled with the depletion of the traditional energy resources, many initiatives globally have addressed the efficient use of these resources. Since then, several renewable energy sources have been introduced as alternatives to traditional resources to protect environmental resources and to improve quality of life. Globally, there are more than a quarter of the human population experiencing an energy crisis, particularly those living in the rural areas of developing countries. One typical example of this is Nigeria. This is a country with approximately 80% of her population consistently relying on combustible biomass from wood and its charcoal derivative. Nigeria has an abundant amount of both renewable and fossil fuel resources, but due to the lack of a reasonable energy policy (until recently), it has concentrated on traditional fossil fuels alone. Renewable energy is now Globally considered as a solution for mitigating climate change and environmental pollution. To assess the sustainability of renewable energy systems, the use of sustainability indicators is often necessary. These indicators are not only able to evaluate all the sustainability criteria of the renewable energy sources,1 but also can provide numerical results of sustainability assessment for different objective systems.