The scope of this project is to investigate if the software Ecolego is suitable for creating models in accordance with level 3 PSA, with the goal of creating a model calculating the possible outcomes for the radiological impact at 20 km distance resulting from a fictional severe nuclear accident at the Forsmark Nuclear Power Plant. This report aims to answer the questions “What is the concentration on the ground (kBq/m2), at a distance of 20 km, 30 days and 10 years after the fictional severe nuclear accident, with and without filtered venting” and “Is Ecolego a suitable software for level 3 PSA models?” The source term for the fictional severe nuclear accident is made to resemble the actual source term from the Fukushima Daiichi accident including the radionuclides Cs-134, Cs-136, Cs-137, I-131, I-132, I-133 and Te-132. In the model, three source terms are created and tested. Two source terms in which the total emissions are released in 24 hours, for which one contains the total emissions from the Fukushima Daiichi accident and one containing 1 percent of the emissions from the Fukushima Daiichi accident due to reduction of emissions when passing the filtered venting. The thirdsource term is made to resemble the time-dependent emissions for the Fukushima Daiichi accident, with emissions varying in intensity over 50 days. The transport of the radionuclide concentration is only due to atmospheric dispersion in the model, for which the Gaussian Plume Model (GPM) is applied under undisturbed condition where only the concentrations in the centerline of the plume are calculated. Probabilistic variation is performed with Monte Carlo simulations where probability density functions (PDFs) are assigned to wind speed andprecipitation, with 5000 iterations. Simulation of the model with one of the two source terms which has the release period of 24 hours gives reasonable results. However, to run the simulation with the time varying source term the model needs to be developed to generate reasonable results, for which necessary development actions are presented. The calculations of the resulting concentration on the ground 30 days and 10 years after the fictional accident shows that there are multiple possible outcomes, which makes it impossible to give a single answer to the expected concentration on the ground. Due to their short half-lives, there will be no concentrations of I-132 and I-133 on the ground at the distance 20 km after 30 days or 10 years. For the remaining radionuclides, the ranges of the possible outcomes for the concentration on ground are presented. It is concluded that Ecolego is suitable for PSA level 3 with the risk metric of environmental impact based on the results of the investigation. However, due to the time limit of the investigation, the applicability of creating an Ecolego model with the risk metrics health effects and economic impact are not investigated. But the report discusses suitable development of the model to contain the risk metric health effects in accordance with level 3 PSA. With such development the conclusion is that Ecolego is suitable for level 3 PSA.

Reliable, affordable access to electrical power is a requirement for almost all aspects of developed societies. Challenges associated with reducing carbon emissions has led to growing interest in nuclear-renewable hybrid energy systems (N-RHES). Much work has already been done in suggesting and analyzing various N-RHES using a variety of optimization techniques and assumptions. This work builds upon previous techniques for simultaneous combined design and dispatch optimization (CDDO) for hybrid energy systems (HES). The first contribution of this work is the development and application of sensitivity analysis tailored to the combined design and dispatch optimization problem. This sensitivity analysis cover uncertainty in design parameters, time series and dispatch horizon lengths. The result is a deeper insight into which sources of uncertainty are most important to account for and how the uncertainty around these sources can be quantified. The second contribution of this work is a novel multi-scale optimization algorithm for the combined HES design and dispatch optimization. This algorithm supports optimization of nonlinear models over very long-time horizons. This method is based on a multi-dimensional distribution of the optimal capacities for a system as determined by a large number of combined design and dispatch optimization problems each covering a subset of the complete time horizon. This method shows good agreement with the direct solution to multiple example systems and is then used to solve a problem with a dispatch horizon length 112.5 times longer than is solvable directly. The third contribution of this work is the application of the novel multi-scale method to three HES. Each of the application systems is used to demonstrate the strengths, validation and applicability of the developed algorithm to a wide range of possible HES/NHES designs.

The transition from combustion engine vehicles to electric vehicles (EV) is an important step in achieving a carbon neutral society, but poses future difficulties in energy production. This is an issue in sustaining sufficient net energy, as well as providing sufficient power during hours of high demand. Vehicle to grid (V2G) may serve as a means of mitigating the power related issues. The main restraints are that battery state of charge (SoC) must be high enough when transportation is desired, and that the added energy flux through the battery causes additional wear. Furthermore, the production of batteries is heavily energy demanding, and the supply chain prompts environmental concerns. This study examines V2G profitability and environmental impact through modelling and simulation using Python. A battery degradation model is constructed based on life cycle versus depth of discharge, a N(D)-function. A V2G-system for one vehicle is simulated with t = 8736 h. Profitability is determined applying parameter optimization of maximum SoC and minimum difference in price of bought and sold energy. Evironmental impact is assessed with GWP100, and presented in terms of g CO2e per discharged kWh of energy from the battery. The results show that battery degradation is an important factor in determining profitability, but do indicate that profit is possible. However, the N(D) based modelling involves a risk of underestimating battery degradation due to insufficient model complexity. Calculated environmental impact is low, which is partly a result of low battery degradation, but there is a lack of similar studies on other energy storage methods, leading to difficulties in making useful comparisons.

Omställningen till förnyelsebara energikällor innebär att bland annat elproduktionen från vattenkraftverken måste utökas. I Sverige är vattenkraften redan etablerad och platser att bygga nya vattenkraftverk på är få. Därmed är det viktigt att ta vara på de vattenkraftverk som är i drift och om möjligt utöka elproduktionen i de kraftverken. En utökning av elproduktionen i ett vattenkraftverk kan bland annat genomföras genom att rensa och bredda utloppskanalen vilket ökar fallhöjden. Målet för den här studien var att finna den ekonomiskt mest optimala volymen att rensa i utloppskanalen från Rottnens vattenkraftverk för att utöka elproduktionen. Rottnadammen är placerad i anslutning till Rottnens vattenkraftverk och ska eventuellt rivas. En dammrivning medför miljökonsekvenser. Målet från studien var att undersöka vilka miljökonsekvenser en dammrivning medför. För beräkningen av elproduktionseffektiviseringen i Rottnens vattenkraftverk användes programvaran HEC-RAS. HEC-RAS användes för att simulera hur vatten- nivån i utloppskanalen förändras när olika volymer har rensats. För att undersöka miljökonsekvenser av en dammrivning genomfördes en litteraturstudie. Elproduktionsökning i Rottnens vattenkraftverk är möjlig genom rensningar i utloppskanalen i samband med att vattenintaget till Rottneros bruk flyttas från Rottnens vattenkraftverk till sjön Fryken. Det är ekonomiskt mest optimalt att rensa cirka 20 000 m3 vilket medför en elproduktionsökning på ungefär 1,1 GWh/år för ett statistiskt normalår. Inkomsten till följd av elproduktionsökningen är cirka 750 Kkr/år. Investeringskostnaden för en rensning på 20 000 m3 är ungefär 7 300 Kkr. Återbetalningstiden för investeringen är ungefär 16 år. Flytten av vattenintaget innebär att flödet som i dagsläget tas ut från bruket vid Rottnens kraftverk istället kan adderas till flödet som går genom vattenkraftverket och därmed utöka elproduktionen ytterligare. Med det extra flödet skulle elproduktionsökningen i Rottnens vattenkraftverk bli ungefär 1,7 GWh/år för rensning av volymen 20 000 m3 vilket skulle bidra till en inkomst på cirka 1 200 Kkr/år.Resultatet från litteraturstudien visar att det är viktigt att undersöka miljö- konsekvenser av en dammrivning för att kunna göra miljömedvetna val. För en eventuell rivning av Rottnadammen är det viktigt att ta hänsyn till vilken tid på året som rivningen sker för att minimera mängden organiskt material som flödar ut i sjön Fryken. Hastigheten av tömningen är också en viktig faktor för att dammrivningen ska medföra så liten påverkan som möjligt på ekosystemen i och omkring dammen.

The built environment accounts for 40% of annual carbon dioxide (C02) emissions. Among the total emissions, building operations generate approximately 27% annually. Other than this, building materials, infrastructural materials, and construction (embodied carbon) contribute to an additional 13% annually [1]. C02 emissions to the environment account for global warming and contribute to climate change. In response to the environmental problems and in line with the objectives of the Paris Agreement, the European Union is committed to developing a sustainable, competitive, secure, and decarbonized energy system by 2050. The goal of decarbonization in building stocks is already set to be achievable this year. To achieve these set objectives, it is necessary to shift to the usage of renewable energy in the building industry and also technologically improve measures to reduce energy demand in building stocks which will reduce carbon footprints. In line with the Energy Performance of Building Directive (EU 2018/844), it is stated that one of the applied measures from the year 2021 will be that all new buildings and deep renovations should be at least a nearly zero energy building (NZEB) standard. But in this context of research work, positive energy building (PEB) through retrofitting is the goal. PEBs contribute to the EU’s target for decarbonization of the energy supply and a shift from fossil fuels to Renewable energy sources (RES) [2]. This thesis aims to study the possibility of achieving a PEB in the existing cluster of two-storey multifamily apartments by analyzing its detailed energy demand and its Solar PV production capability. The result is to contribute to the body of knowledge of the SOLVE theme 3 research members. The project location is at Rymdgatan, Petter Blåders väg, Borlänge, Sweden. The building stock has a total of 80 residential units and other ancillary buildings on a land area of 4,682 m2 . IDA ICE 4.8 software by EQUA was used in simulating the annual energy demand in the building envelopes when retrofitted with different energy-efficient measures. The 5.0 beta version of this tool was used to simulate energy production from the solar PV system. The base case shall be by using the district heating energy system and other energy carriers shall be by using the ground source heat pump borehole, heat recovery ventilation system, and the addition of solar PV system. In the base case, the total simulated annual energy demand was 492 MWh with the pre-condition of opening windows during summer and using an external window shading technique for thermal comfort indices to be kept at a very a good level. Retrofitting by changing the window glazing type and by adding extra insulation to the internal walls also provided a very good energy saving procedure. With these, an annual energy demand simulated for the Rymdgatan housing cluster reduces to 409 MWh/year. In another scenario, the heat pump replaced district heating as the energy carrier. With this, annual energy demand was reduced to 208 MWh with an increased primary energy number. With a heat recovery ventilation system, annual energy demand is further reduced to 205 MWh/year. Using IDA ICE 5.0, the main building´s roof area of 1,900 m2 generated 247 MWh of DC power from solar PV annually when tilted at an angle of 150 . This on-site energy generation with a heat pump and heat recovery system made the Rymdgatan housing cluster to be self-sufficient in energy balancing with a total surplus energy of 14% when heat pump is used and 20% if heat recovery system is incorporated into the system. The perspective of decreasing the set-point temperature by 10C from the acceptance value of 210C in the base case results in annual energy being improved by 5.7% while with a ground source heat pump system it was 4.6% for a chosen built model type A.

In order to ensure a stable power system, a balance between production and consumption at every given moment is necessary. An indication of this balance is the system frequency, which deviates from its nominal value in case of imbalance. With an increasing share of weather dependent energy in the Nordic synchronous system, such as wind power, the need for stabilizing services are becoming even more crucial. Ancillary services are a way of keeping the frequency stabilized, they are provided by different actors in the power system with flexible production or consumption. This contributes to increasing or decreasing the input and output of energy to the system when needed. Ancillary services are procured in separate markets that are structured and designed by the transmission system operator, Svenska kraftnät. This thesis investigates wind power and its potential of providing ancillary services in the Swedish power system. The report presents two different studies which are performed based on two specific wind farms in Sweden. Firstly, the possibility of providing ancillary services by the wind farms alone are considered with emphasis on the economic profitability. A model is used to present a theoretical maximum of income based on historical production and market data from 2022. The second study has an additional aspect of combining the wind farms with a battery energy storage system (BESS), creating a hybrid system, to examine the potential improvement of income for the company. Due to the production being dependent on weather conditions, the BESS can provide additional contribution when needed. The second study is performed using an optimization model in order to optimize the use of the BESS for the simulated period. The results presented an increase of revenues when participating on the ancillary service markets for both studies. The first study showed that down regulating services were the most profitable, this being FCR-D down and aFRR down. With the hybrid system, the profitability was even more significant. It demonstrated a big potential of participating on the FFR market during the summer and FCR-D during winter. Furthermore, the hybrid system also showed an increase in participation on the up-regulating markets. Without the BESS, the windfarm is forced to curtail production toparticipate in the up-regulating markets, which proved to be less profitable than participating on down-regulating markets. The results also give an understanding of the cycling of the BESS and how this affects the results and the BESS lifetime. With coming market development, the conditions on the ancillary service markets is expected to change, the effect of this is considered in a sensitivity analysis. Finally, the studies collectively show the opportunity for wind power to contribute to stabilizing the power system and ensuring the security of energy supply in the Nordicsynchronous system.

The transition to a fossil-free industry is a current topic, and in Swedish industry, energytransition of existing energy systems is promoted to reduce climate impact. Energy transitioninvolves a structural change in the energy system with a focus on energy use and energysupply. To reduce global greenhouse gas emissions, the transition can be achieved throughelectrification and the use of biomass. Currently, sawmills combust significant amounts of biomass to meet the heat demandof industrial wood drying. As the biomass used is a by-product of the sawmills’ otherproduction processes, this combustion is usually considered sustainable and circular. However,some research indicates that increased biomass usage in several industrial sectors can leadto overexploitation of the resource with negative environmental impacts. Despite thesedisagreements, many argue that bio-based residual flows must be utilised efficiently to meetsociety’s future biomass needs. Against this background, it needs to be examined whether sawmills should continue tocombust biomass or whether an energy transition would be more economically and ecologicallysustainable. The aim of this study is to investigate how energy use in the sawmill industrywill change in the future and what potential consequences this change may have. In addition,the possibilities and feasibility of electrifying the drying process in the sawmill industryare investigated. To achieve this purpose, a literature search and an interview study wereconducted. The results from these parts form the basis for a scenario-based quantitativestudy of the consequences of different energy transition cases. The results show that future energy use in the sawmill industry will be affected by severalfactors. One important factor is the price of biomass, which can provide an incentive toelectrify the energy-intensive drying process. However, it can be challenging to make anelectrified drying process profitable, and until then energy efficiency will be prioritised ratherthan biomass replacement. The results also indicate that electrification of the drying processcan reduce the climate impact, assuming that the electricity source is fossil-free. The releasedbiomass can then be used more efficiently than incineration, and the optimal use may be toproduce long-life products. Clear knowledge gaps have been identified regarding the electrification of the drying processand its potential consequences. Since the sawmill industry is not ready for an energytransition today, there is time to fill these gaps and develop the electrifying processes. Furtherinvestigations should be conducted on various aspects of electrified drying through in-depthmodelling and analysis of the sawmill energy system. Additionally, future studies couldinvestigate the extent of the impact of sawmill biomass release on the surrounding energysystem.

In this study, the parameters of population, gross domestic product (GDP), heat price, U-value, and temperature have been used to predict heat consumption for Sweden till 2050. It should be noted that the heat consumption has been considered for multi-family houses. Most multi-family houses (MFH) get their primary heat from district heating (DH). A literature analysis of various models and variables has been conducted to enhance comprehension of forecasting and its process. The majority of earlier research has focused on electricity or energy rather than heat. The aim of this study is to create a model (linear and non-linear) from 1993 to 2019 with a minimum error as possible, and then use the genetic algorithm (GA) and neural network (NN) to predict Sweden's heat consumption till 2050

Backup power is essential to supply important functions in society with electricity in case of a blackout. Today in Sweden most backup generators are based on diesel fuel and seldom used, but they are still associated with bad environmental impact while operating. What if a backup system could be designed to increase its value and at the same time lower the environmental impact? This study has investigated alternative solutions for backup power and applied them on a specific case. A food providing industry with great variations in their load profile (40 - 240 kW) is looking for a backup solution able to supply the industry for 12 h in case of a blackout. The study started off by investigating different techniques and their suitability for providing backup power, such as diesel generators (DG), battery energy storage systems (BESS), micro gas turbines (MGT) and fuel cells (FC). Most suitable to be compared with the traditional diesel solutions in terms of cost, climate and technique was found to be two hybrid systems. The first one a combination of a DG and BESS and the second a combination of a MGT and BESS. The two hybrid systems were primarily dimensioned to a size of 100 kW (DG/MGT) with a 350/350 kWh/kW BESS based on terms and after analyzing the industry's load profile. The two hybrid systems were compared with a 350 kW DG in two aspects over a time frame of 15 years, life cycle costs (LCC) and carbon dioxide emissions. Compared with only DG the result showed a 15% LCC increase and a 26% emission reduction for the hybrid solution with DG + BESS. For MGT + BESS the LCC increase was 30% but the emission reduction was 52%. Included into the LCC analysis is utilization of the BESS for grid services such as peak shaving, arbitrage and grid support which had a major positive economic impact. The LCC results were however sensitive to changes in some parameters such as investment costs and rates. Finally, the study tried to optimize the cost and climate performance of the two hybrid systems. By reducing a few terms, sizing of the systems could be adjusted. This resulted in both hybrid systems being more profitable and climate friendly with a larger DG/MGT and a smaller complementing BESS for peak loads, outperforming the only DG solution.

This thesis examines the possibilities and limitations of connectingoffice buildings to demand response (DR) programs, with emphasis on the effect it has on indoor climate. Heating, ventilation and airconditioning (AC) systems was used as sources to scale power, and thereby contribute with power to capacity markets related to the electrical grid. By simulations performed in MatLab, as well as livetests in one of Vasakronan’s buildings, this work contributes with knowledge of DR in office buildings in the Swedish environment, which to date have been lacking in literature. All systems considered in thisreport has potential to contribute with power to DR programs. Heating and AC systems has greater power saving potential than the ventilation system. However, ventilation also holds potential as a source of power savings and is applicable to a larger portion of the building stock.Indoor air carbon dioxide level is affected to varying degrees depending on the extent of power reduction, where a reduction up to 90 % of ventilation is possible without exceeding approved limits. Reduction of ventilation caused the highest rise in carbon dioxide levels during mid- day and especially during the winter. Flexibility is key for the control system, especially when considering future climate challenges andtrends. DR strategies should include control of all systems both during the active DR time but also when returning to normal activity to reduce the risk of compensation from other systems.