Offshore wind is rapidly growing and optimised grid connections are crucial for its success. Generally, costs and losses are higher for HVDC at short distances due to the converters, while HVAC costs and losses increase more rapidly with distance due to the ac cables. Hence, there is a breaking point over which HVDC becomes beneficial, which is important knowledge for grid connection design. Recent research and practice indicate increasing distances for the breaking point, enabled by the introduction of offshore reactive compensation substations (RCS) for HVAC. In the study, steady-state models of HVAC and modular-multilevel converter (MMC) based VSC HVDC systems up to 260 km have been simulated in the Matlab/Simulink based program EeFarm-II. For base case assumptions, the average loss breaking point is 80 km and the levelised cost breaking point is 229 km. The resulting breaking point with respect to levelised cost of energy (LCOE) is 205 km and with respect to net present value (NPV) 186 km, agreeing with the trend of increasing breaking points. Given the range of distances in literature, it is of interest to also investigate how the breaking point depends on assumptions on technical, practical and economic parameters. For the NPV breaking point: lifetime and interest rate have no impact, availability and cost of RCSs have low impact, electricity price has moderate impact, operation and maintenance (O&M) cost has high impact while investment cost and lead time have very high impact. This could be taken into consideration in offshore projects and in future research.

A climate-neutral city can be viewed at in many different aspects. This report investigates the greenhouse gas, exergy and energy balance for both heat pumps and district heat supply at local, national and methane gas perspectives of the energy conversion processes. Through a numerical grey box model of a geographical information system based urban district. There seven different passive-, nearly zero-, and plus-energy residential buildings are implemented. That are developed and annually simulated in the IDA ICE software. There, thermal transmittance and building geometry are the most urgent parameters that impacts the space heating demand and energy performance. They are estimated by current and proposed primary energy weight factors where the geometry shape is undefined, while the altitude impact’s the building's energy, exergy, and greenhouse gas balance. Therefore high-rise building's energy performance are poorer than low-rise buildings, simultaneously as heat pump supply enables higher altitude than district heating. Other energy savings occur through additional energy-efficient technologies, energy generating technologies and soft tools that change residents’ behavior. The investigated urban district is placed in the Swedish city Gävle, which meets residents’ demand for approximately 6000 apartments without additional service. It is a plus energy district for heat pump supply and passive energy for district heating supply. Although the district heated urban district electricity-saving towards heat pump corresponds to 32 percent of the urban district's total facility and household electricity utilization. The energy analysis include the perspective of the facility’s energy utilization and generation, and the perspectives of residents’ energy utilization and recovery from their waste resource production. This makes the urban district exergy productive and carbon-negative during the operating phase, regardless of emission value and heat supply technology, since the facility perspective compensates for the residents’ electricity utilization and consumption of goods. Therefore, there are no need for tree plantation as compensation of greenhouse gas pollution since the carbon negativity corresponds to between 2 to 154 hectares of forest. The study is therefore relevant for other geographical locations in Sweden depending on geographical location, heat supply technology and emission value from the primary energy conversion processes. / <p>Förstudie i future heat projekt angående Framtidens klimatsmarta stad genom klimatneutral bebyggelse med fjärrvärme.</p>

Municipal energy systems in Nordic environments face multiple challenges: the cold climate, large-scale industries, a high share of electric heating and long distances drive energy consumption. While actions on the demand side minimize energy use, decarbonization efforts in mining, industries, the heating and the transport sector can increase the consumption of electricity and biofuels. Continued growth of intermittent wind and solar power increases supply, but the planned phase out of Swedish nuclear power will pose challenges to the reliability of the electricity system in the Nordic countries. Bottlenecks in the transmission and distribution grids may restrict a potential growth of electricity use in urban areas, limit new intermittent supply, peak electricity import and export. Environmental concerns may limit growth of biomass use. Local authorities are committed in contributing to national goals on mitigating climate change, while considering their own objectives for economic development, increased energy self-sufficiency and affordable energy costs. Given these circumstances, this thesis investigates existing technical and economic potentials of renewable energy (RE) resources in the Nordic countries with a focus on the northern counties of Finland, Norway and Sweden. The research further aims to provide sets of optimal solutions for sustainable Nordic municipal energy systems, where the interaction between major energy sectors are studied, considering multiple objectives of minimizing annual energy system costs and reducing carbon emissions as well as analyzing impacts on peak electricity import and export. This research formulates an integrated municipal energy system as a multi-objective optimization problem (MOOP), which is solved by interfacing the energy system simulation tool EnergyPLAN with a multi-objective evolutionary algorithm (MOEA) implemented in Matlab. In a first step, the integration or coupling of electricity and heating sectors is studied, and in a second step, the study inquires the impacts of an increasingly decarbonized transport sector on the energy system. Sensitivity analysis on key economic parameters and on different grid emission factors is performed. Piteå (Norrbotten County, Sweden) is a typical Nordic municipality, which serves as a case study for this research. The research concludes that significant techno-economic potentials exist for the investigated resources. Optimization results show that CO2 emissions of a Nordic municipal energy system can be reduced by about 60% without a considerable increase in total energy system costs and that peak electricity import can be reduced by up to 38%. The outlook onto 2030 shows that the transport sector could be composed of high electrification shares and biofuels. Technology choices for optimal solutions are highly sensitive to electricity prices, discount rates and grid emission factors. The inquiries of this research provide important insights about carbon mitigation strategies for integrated energy sectors within a perspective on Nordic municipalities. Future work will refine the transport model, develop and apply a framework for multi-criteria decision analysis (MCDA) enabling local decision makers to determine a technically and economically sound pathway based on the optimal alternatives provided, and analyze the existing policy framework affecting energy planning of local authorities. / Kommunala energisystem i nordiska miljöer möter flera utmaningar: det kalla klimatet, storskaliga industrier, en stor andel elvärme och långa distanser driver energiförbrukningen. Medan åtgärder vidtas på efterfrågesidan för att minimera energianvändningen, kan utsläppsminskande åtgärder inom gruvdrift, industrier, uppvärmningen och transportsektorn öka förbrukningen av el och biobränslen. Fortsatt tillväxt av intermittent vind- och solkraft ökar elproduktion, men den planerade avvecklingen av svensk kärnkraft kommer att utmana tillförlitligheten i elsystemet i de nordiska länderna. Flaskhalsar i överförings- och distributionsnäten kan begränsa en potentiell tillväxt av elanvändningen i stadsområden, begränsa ny intermittent utbud, och påverka elutbyte mellan länderna. Miljöhänsyn kan begränsa ökad användning av biomassa. Lokala myndigheter är engagerade i att bidra till nationella klimatmål, samtidigt som de följer sina egna mål för ekonomisk utveckling, ökad självförsörjning av energi och överkomliga energikostnader. Mot bakgrund av dessa omständigheter undersöker denna avhandling befintliga tekniska och ekonomiska potentialer för förnybar energi i Norden med fokus på de nordliga länen i Finland, Norge och Sverige. Forskningen syftar vidare till att utveckla optimala lösningar för hållbara nordiska kommunala energisystem, där samspelet mellan stora energisektorer studeras, med tanke på att minimera årliga energisystemkostnader och samtidigt minska koldioxidutsläppen samt analysera påverkan på elimport till och export från kommunen. Denna forskning formulerar ett integrerad kommunalt energisystem som multimåloptimeringsproblem (multi-objective optimisation problem - MOOP), som löses genom att kombinera simuleringsverktyget EnergyPLAN med en evolutionär algoritm implementerad i Matlab. I ett första steg studeras kopplingen av el- och värmesektorerna, och i ett andra steg effekterna av en integrerad och alltmer förnybar transportsektor på energisystemet. Känslighetsanalys på viktiga ekonomiska parametrar och på olika utsläppsfaktorer utförs. Piteå (Norrbottens län, Sverige) är en typisk nordisk kommun som fungerar som en fallstudie för detta arbete. Forskningens slutsatser innebär att det finns betydande teknisk-ekonomiska potentialer för de undersökta förnybara resurserna. Optimeringsresultaten visar att koldioxidutsläppen från ett nordiskt kommunalt energisystem kan minskas med cirka 60% utan en avsevärd ökning av de totala energisystemkostnaderna och att den högsta elimporten kan minskas med upp till 38%. Resultat för år 2030 visar att transportsektorn kan ha en mycket hög elektrifieringsgrad och samtidigt används biobränslen i tunga fordon. Optimala lösningar är mycket känsliga för elpriser, räntor och utsläppsfaktorer. Detta arbete ger viktiga insikter om strategier för koldioxidminskning för integrerade energisektorer i ett perspektiv på nordiska kommuner. Min framtida forskning kommer att förfina transportmodellen, utveckla och tillämpa ett ramverk för beslutsanalys med flera kriterier (multi-criteria decision analysis - MCDA) som ska stödja lokala myndigheter att fastställa tekniskt och ekonomiskt hållbara lösningar i deras energiplanering.

Wind resources are highly intermittent and fluctuant, making wind turbines less reliable and the unstable power output will affect grid stability and security. This paper presents an idea of integrating the solar PV plant and energy storage system into an existing wind project, project Rödene in Gothenburg. The hybrid renewable system, which consists of two or more renewable energy sources, is considered the renewable energy development trend. An economic analysis of a 1.2 MW PV plant, 5 MW lithium-ion battery storage system and 300 kg hydrogen fuel cell storge system are assessed in terms of LCOE and LCOS of plants. The revenue stream is discussed separately, consisting of electricity tariff, ancillary services and energy arbitrage. The results show that both PV plant and energy store systems are unprofitable. When the PV panel cost is reduced more than 30% and the annual production increases at least 30%, the LCOE of the PV plant arrives at the break-even point. Also result shows the hydrogen fuel cell energy storage system is too expensive of commercial use, and the battery energy storage system has a high potential of profitable if the ancillary service in Sweden is well organized in the future

This is a report of a verification study of the multiphysics simulation framework MOOSE which was preformed at the company Seaborg Technologies. In the process of designing molten salt reactors there is a special need of making credible multiphysics simulations since the fuel is in motion. In this study the incompressible version of Navier-Stokes equations of finite volumes available in the Navier-Stokes module of the MOOSE framework is verified by modelling and simulations of fluid flow and heat transfer in two different systems with available benchmarks. The first system, a thin buoyancy driven molten sodium hydroxide test loop which is verified by a similar model made with the high fidelity CFD software STAR-CCM+ as benchmark. The second system, forced convection of air through a straight pipe with heated walls which is verified by comparisons with an analytical solution. The resulting velocity profiles from simulations of the first system corresponds well with the benchmark but certain conclusions can not be drawn from it since the the transient simulations stops to converge before reaching equilibrium. The results from simulations of the second system corresponds well with the analytical solution and no convergence issues arise. The conclusion from the results is that the incompressible version of Navier-Stokes equations of finite volumes available in the Navier-Stokes module of the MOOSE framework has potential to be used in multiphysics simulations of molten salt reactors but seemingly not in cases of buoyancy driven flows in thin geometries. Two proposals for further work is recommended. The first is that this implementation is applied in a context with forced fluid flow or a context with thicker fluid domain. The second proposal is that the other available abilities of MOOSE such as finite element method and/or the compressible version of the Navier-Stokes equations should be tested.

The study sets out to review various literatures concerning photovoltaic/thermal (PVT) modules for the extraction of electricity and heat, it also reviews different PVT collectors as well as their performance. The study provides an understanding of a system that fully supports ecological society by promoting the use of solar modules from a different scope in future global resolutions. Furthermore, it looks into renewable energy in Sweden, solar energy and PVT systems, operational principles of hybrid PVT collectors, PVT applications, PVT market and legal face of PVT in Sweden among others. Among other social benefits, PVT system contributes enormously to energy savings and energy consumption which in turn lowers CO2 emissions. The review shows that PVT modules can provide homes and industries with 100% renewable electricity and heat that is affordable. This paper adopts systematic literature review, as it allows thorough cross-examination of various publications regarding the subject.

The increasing demand for renewable energy sources to meet climate targets and reduce carbon emissions poses challenges to the power grid due to their intermittent nature. One potential solution to maintain grid stability is by implementing Hybrid Energy Systems (HESs) that incorporate a Battery Energy Storage System (BESS). To achieve the most favorable outcome in terms of both technical feasibility and profitability of a BESS, it is essential to employ models for simulating and optimizing the control of system components. This thesis focuses on the analysis of energy and revenue streams in a HES consisting of a BESS, photovoltaics (PVs), and an energy load including a fast charging station for electric vehicles (EVs). The objective is to optimize the system based on revenue generation by comparing the control techniques of peak shaving, energy arbitrage, and the integration of ancillary services within the Swedish energy market. The research questions explore the optimal utilization of the BESS and assess the impact of the different control techniques. A model is created in Python with the package CasADi where data from an ongoing installation of a HES in southern Sweden is combined with data from literature research. The model includes an objective function that minimizes the total cost of power from the grid based on the day-ahead price, battery degradation, and monthly peak power.  To answer the research questions, four different scenarios are simulated. The first scenario is a base for comparison, the second one focuses on peak shaving and energy arbitrage, the third on participation in the ancillary service FCR-D upwards regulation, and the last one is a combination of peak shaving, energy arbitrage, and the ancillary service FCR-D. The results show that the remuneration from the ancillary service FCR-D is comparably much higher than the revenues generated from peak shaving and energy arbitrage, providing more than 500% of revenue compared to the same system but without a BESS. The scenario with peak shaving and energy arbitrage shows an increase in revenue of 29% but with more cycling of the battery which could cause losses in performance in the long term. To validate the results, sensitivity analyses are conducted by evaluating weighting in the objective function, implementing Model Predictive Control (MPC), and reviewing price variations.  In conclusion, efficient control techniques can enhance system performance, minimize losses, and ensure optimal utilization of different energy sources, leading to improved feasibility and profitability. The optimal usage of a BESS involves finding a balance between maximizing revenue generation and minimizing battery degradation. This can be achieved through control strategies that optimize the charging and discharging patterns of the BESS based on electricity price signals, demand patterns, and battery health considerations.

The construction sector is responsible for 20% of Greenhouse Gas (GHG) emissions, of whichdiesel-powered construction equipment are large contributors. Currently there are many ongoing Fuel Cell (FC) powered construction equipment projects as it is seen as an attractiveoption to power the futures zero-emission heavy-duty machines. Although an attractivealternative, hydrogen FC has drawbacks such as releasing liquid water and water vapor viathe exhaust as a byproduct which in their working environment can cause a suite of issues. Agap in the literature on the water exhausted is present and therefore this degree project seeksto investigate the amount, and ratio, of liquid water and water vapor released from threetypical construction equipment drive cycles which would allow further investigation onappropriate management. The method used for this degree project was to modify a pre-mademodel in Simulink built with Simscape blocks. The model was modified to represent a FCsystem used in a test-rig by implementing experimental and measured data for design andoperating parameters. Different pressures, temperatures, and cathode inlet RelativeHumidity (RH) were investigated to find their effect on the performance and water in theexhaust. A sensitivity analysis of different unknown parameters was also conducted tounderstand their influence on the results. For the reference case, the results showed that foran articulated hauler, the water in the exhaust was 26% liquid which translates to 8.6 kg for a1-hour drive cycle. The crawler excavator and wheel loader, both had 30-minute drive cyclesand had 1.1 kg liquid water with a liquid water ratio of 7% and 0.7 kg liquid water with aliquid water ratio of 5% in the exhaust respectively. For a full 8-hour workday with twoparallel FCs connected, the articulated hauler liquid water amount is 137.6 kg, the crawlerexcavator 35.2 kg, and the wheel loader 22.4 kg. Overall, it was found the liquid water ratiocould be changed to a large extent with different operating parameters, where thetemperature had the greatest influence. The system and stack efficiencies did not changeconsiderably with different operating parameters, meaning that the total water in the exhaustremained similar for the different respective drive cycles.

The goal of achieving carbon neutrality for year 2045 puts Sweden on a road towards further implementation of renewable energy into their energy system. The goal of this degree project is to investigate how the implementation of renewable energy in Sweden is worked towards on a regional level but also to explore how this expansion might look for the Norra Småland Region. By conducting several semi-structured interviews with the energy agencies of Sweden as well as creating a model for the potential solar and wind power expansion in the Norra Småland Region, the authors aim to answer the questions of how the current work with expanding the renewable energy share in the Swedish energy system is conducted; what bottlenecks, problems and challenges exist and what tools, data, information and incentives might help further facilitate this work. Through the interviews conducted, this degree project encapsulates the different projects related to the subject of renewable energy which the various regions of Sweden work with. The degree project also provides a compilation of various challenges related to the projects as well as an insight into what tools and incentives are asked for by the regions with the goal of helping facilitate the work conducted. The degree project also provides a projection for how the future expansion of wind power and solar power might look in the Norra Småland Region based on the previous expansion trends, resulting in three individual projections with individual growth rates.

Climate change represents a critical threat to electrical infrastructure. With reliance on electricity expected to increase in Sweden due to the transition from fossil fuel based energy to greener energy sources, it is important that the reliability of the electrical grid be upheld. This thesis studies the potential climate affected effects of extreme precipitation, annual average temperature change, water pooling after 100/500-year rains, and sea level rise. The RCP scenarios used for extreme precipitation and temperature change are RCP 4.5 and RCP 8.5. These climate effects will be studied in this thesis to understand and determine the extent of the climate effects on the electrical grid of Gotland and Klintehamn. The possible issues on infrastructure that can be exacerbated by these climate effects will be presented. This thesis will use spatial analysis to find results using GIS as a tool. GIS will be used to compare the various climate effects over the electrical grid data. Data was received from various sources, extreme precipitation and temperature change were sourced from SMHI, water pooling, and sea level rise were sourced with permission from Region Gotland. The electrical grid data for both Gotland and Klintehamn was received from GEAB, this data is considered nationally sensitive information therefore the location of this data is not shown. The results generally show that climate change, no matter the scenario presents a threat to the infrastructure. Although it should be noted as well that the scenario will impact the severity of the effects. RCP 8.5 will likely have more of an effect for both extreme precipitation and temperature than RCP 4.5. Water pooling is expected to have a greater effect on the &lt;20kV lines than on the 70kV infrastructure. Finally, sea level rise is expected to have a much greater effect from 2-meter sea level rise over the 1-meter sea level rise. The overarching theme found is that climate change will have impacts over the electrical grid.