After the nuclear fallout in Japan, Germany decided to back out from nuclear energy while at the same time changing the energy supply from fossil to renewable sources. This elaborate plan, known as Energiewende, will require significant economic and structural efforts that will have profound impacts on the environment and society itself. It is therefore crucial to identify possible technological pathways that can lead to a renewable energy supply, while reducing negative impacts on a holistic scope. In order to analyse alternative energy technology scenarios in Germany, this thesis focuses on the development of an indicator-based numerical Sustainable Energy Systems (SEnSys) model approach. Other than previous approaches, the SEnSys model considers full aggregated impacts of technological pathways leading to future configurations. With the help of an exemplary case study on two alternative energy technology scenarios (Trieb1 and Trieb2), the feasibility of the SEnSys model in evaluating sustainability is subsequently assessed. The results can affirm the findings of previous studies concerning lower economic and environ- mental impacts for scenario Trieb2, with small shares of renewable energy imports, compared to scenario Trieb1 based on only local but fluctuating renewables. Additionally, the results are in accordance with other relevant studies, while offering new valuable insights to the topic. Given a comprehensive revision of the identified uncertainties and limitations, it can be stated that the SEnSys model bares the potential for further analysing and improving sustainability of energy technology scenarios in Germany and other countries.

There are two main types of logistical models used for long-term performance prediction of autonomous power systems: time series and probabilistic. Time series models are more common and are more accurate for sizing storage systems because they are able to track the state of charge. However, the computational time is usually greater than for probabilistic models. It is common for time series models to perform 1-year simulations with a 1-hour time step. This is likely because of the limited availability of high resolution data and the increase in computation time with a shorter time step. Computation time is particularly important because these types of models are often used for component size optimization which requires many model runs. This thesis includes a sensitivity analysis examining the effect of the time step on these simulations. The results show that it can be significant, though it depends on the system configuration and site characteristics. Two probabilistic models are developed to estimate the temporal resolution error of a 1-hour simulation: a time series/probabilistic model and a fully probabilistic model. To demonstrate the application of and evaluate the performance of these models, two case studies are analyzed. One is for a typical residential system and one is for a system designed to provide on-site power at an aquaculture site. The results show that the time series/probabilistic model would be a useful tool if accurate distributions of the sub-hour data can be determined. Additionally, the method of cumulant arithmetic is demonstrated to be a useful technique for incorporating multiple non-Gaussian random variables into a probabilistic model, a feature other models such as Hybrid2 currently do not have. The results from the fully probabilistic model showed that some form of autocorrelation is required to account for seasonal and diurnal trends. / Graduate

There has been a significant increase in the interest and implementations of heat pump systems for HVAC purposes in general and of ground source heat pumps (GSHPs) in particular. Though these systems have existed for decades, primarily in Europe, there has been an upward trend particularly in the United States in recent years. With the world-wide push toward CO2 emissions reduction targets, interest in heat pump systems to reduce CO2 emissions from heating and cooling is likely to only increase in the future. However, more than ever, financial considerations are also key factors in the implementation of any system. Ground source heat pumps (GSHPs) coupled to vertical borehole heat exchangers (BHEs) have been promoted as a viable heat pump system in climates where traditional air source heat pumps (ASHPs) may operate inefficiently. This type of system claims superior performance to ASHPs due to the relatively consistent temperature of the ground compared to the air, offering a higher temperature heat source in the heating season and a lower temperature sink in the cooling season. Projects designing and installing such a GSHP system have been implemented at large scales on several university campuses to provide heating and cooling. In this study, we aim to test the idea that a GSHP system, as a replacement for an existing CHP heating and conventional cooling systems, could reduce CO2 emissions, as well as provide a cost benefit to a large energy consumer, in this case the University of Massachusetts. This will be done using the existing heating and cooling loads provided by the conventional system and an established technique of modeling the heat pumps and BHEs. The GSHP system is modeled to follow the parameters of industry standards and sized to provide the best overall lifetime cost. The result on the overall annual costs, emissions, and university microgrid are considered.

The study focuses on the possible positive impacts derived from implementing innovative energy solutions to the Åland energy system by 2030. Four scenarios are formulated in order to determine feasible solutions in economic and technological terms. At the present most of the energy supply relies on the power exchange with mainland by subsea interconnections. The archipelago’s main challenge is to reduce the high dependence from the main importer (Sweden) by increasing the use of local renewable energy sources. Wind power results to be the most favorable form of variable renewable energy (VRE) available. “Behind the meter” photovoltaic (PV) rooftop solar panels, biomass combined heat and power (CHP) generation and a Li-ion battery system are considered as supportive solutions to wind power. The simulations made with RetScreen and EnergyPLAN confirm that solar power and a battery system can only have a modest role compared to wind power. A final economic analysis assesses the revenue projections for the new technologies implemented. The results indicate a very positive investment potential for the new wind farms, coupled with a proper Li-ion battery solution. Additionally, the thesis investigates the best options for solving frequency and voltage imbalances, appearing after the implementation of intermittent energy sources. A flywheel technology has been included in the scenarios in order to enhance the primary frequency control of the whole system.

This thesis has investigated the techno-economic feasibility of upgrading the sludge from a chemical pulp mill to hydrochar via hydrothermal carbonization (HTC). The intended use of the hydrochar was to replace fossil coal within metallurgical applications in the iron and steel industry. Process models were developed in order to obtain mass and energy balances of the HTC process for different technical configurations. The balances were used to evaluate the economic performance, in terms of hydrochar production cost as well as different profitability parameters. Two main scenarios were investigated: Scenario-1: HTC process integrated with the pulp millScenario-2: Stand alone HTC process.To see the effect of having one or two HTC reactors, two cases were developed for each scenario, where the first case used only mixed sludge from the pulp mill as feedstock for the HTC process (case 1, one reactor), while the second case used both mixed sludge and bark as feedstock (case 2, two reactors). In scenario 1, the effects on the pulp mill’s mass and energy balances of integrating the HTC process were investigated. The results showed only very small impacts on the pulp mill, due to that the HTC process is significantly smaller than the mill. The total amount of steam to the steam turbine increased by 0.8 % and 0.9 %, for case 1 and 2, respectively. In combination with the removed sludge, which is otherwise combusted in the mill’s socalled power boiler, this entailed a total increase of the wood fuel consumption in the boiler by 3.2 % and 3.6 %, respectively. By implementing a second HTC reactor, the production cost of hydrochar could in the integrated scenario (scenario 1) be decreased from 4 600 SEK/ton (case 1) to 3 700 SEK/ton (case 2). The corresponding production costs in the stand alone scenario (scenario 2) amounted to 5 400 SEK/ton (case 1) and 4 200 SEK/ton (case 2), respectively. Both integration with the pulp mill and increasing the HTC production scale were thus found to be strategies that can lead to decreased hydrochar production cost. However, even the lowest production cost noted in this report is significantly higher than the corresponding price of coal. This indicates that other measures are required in order for hydrochar to become cost competitive to fossil coal in the metallurgical industry. Examples are the possibility to use even lower-cost feedstocks, as well as policy tools targeting, e.g., the CO2 emissions from using fossil materials and energy carriers in the iron and steel industry. Based on the results from the investment calculation, it is concluded that the HTC process integrated with a pulp mill is preferable compared to a stand alone HTC process. The reason why integrated HTC is preferred is that it gives higher NPV and correspondingly lower payback time, as well as lower hydrochar production costs. / Denna examensarbete har undersökt den tekno-ekonomiska genomförbarheten av att uppgradera slammet från ett kemisk massabruk till hydrokol via hydrotermisk karbonisering (HTC). Den avsedda användningen av hydrokol var att ersätta fossilt kol inom metallurgiska tillämp- ningar i järn och stålindustri. Processmodeller utvecklades för att erhålla mass- och energibalanser för HTC-processen. Balanserna användes för att utvärdera de ekonomiska prestanda, i form av produktionskostnad för hydrokol samt olika lönsamhetsparametrar. Följande två huvudscenarier undersöktes: Scenario-1: HTC-processen integrerad med massabruket Scenario-2: Fristående HTC-process. För att se effekten av att ha en eller två HTC-reaktorer utvecklades två fall för varje scenario, där det första fallet endast använde blandat slam från massabruket som råvara för HTC-processen (fall 1, en reaktor), medan det andra fallet använde både blandat slam och bark som råmaterial (fall 2, två reaktorer). I scenario 1 undersöktes effekterna på massabrukets mass- och energibalanser av att integrera HTC-processen. Resultaten visade endast mycket små effekter på massabruket, på grund av att HTC-processen är betydligt mindre än bruket. Den totala mängden ånga till ångturbinen ökade med 0.8 % och 0.9 % för fall 1 respektive 2. I kombination med bortfall av slammet, som annars förbränns i brukets barkpanna, innebar detta en total ökning av förbrukningen av trädbränsle i pannan med 3.2 % respektive 3.6 %. Genom att implementera en andra HTC-reaktor skulle produktionskostnaden för hydrokol i det integrerade scenariot (scenario 1) kunna sänkas från 4 600 SEK/ton (fall 1) till 3 700 SEK/ton (fall 2). Motsvarande produktionskostnader i det fristående scenariot (scenario 2) uppgick till 5 400 SEK/ton (fall 1) respektive 4 200 SEK/ton (fall 2). Både integration med massabruk och ökning av produktionskapaciteten av HTC visade sig därför vara strategier som kan leda till minskade produktionskostnader för hydrokol . Men även den lägsta produktionskostnaden som noteras i denna rapport är betydligt högre än motsvarande pris på kol. Detta tyder på att det krävs andra åtgärder för att hydrokol ska bli konkurrenskraftigt ur kostnadssynpunkt gentemot fossilt kol i den metallurgiska industrin. Exempel är möjligheten att använda ännu billigare råvaror, såväl som policyverktyg som riktar in sig på t.ex. CO2-utsläppen från användning av fossila material och energibärare inom järn- och stålindustrin. Baserat på resultaten från investeringskalkylen dras slutsatsen att HTC-processen integrerad med ett massabruk är att föredra jämfört med en fristående HTC-process. Anledningen till att integrerad HTC föredras är att det ger högre netto nuvärde (NPV) och motsvarande lägre återbetalningstid, samt lägre produktionskostnader för hydrokol.

With the motivation to mitigate the effects caused by one of humankind’s biggest challenges, climate change, the purpose of this minor field study was to examine the prospects of renewable energy technologies as part of a larger ambition to offer clean and affordable energy for all, in line with United Nations Sustainable Development Goals. The study was conducted for El Alamein in Egypt, a city under construction that will house four million residents. By combining a field study and an interview with literature search, the information needed for an energy system model was gathered. The modelling system OSeMOSYS was thereafter used to calculate the most cost-efficient electricity mix for the model period of 2020 to 2040, based on different scenarios and technologies. The total discounted cost and amount of emissions were thereafter compared between the scenarios, and the most cost-efficient scenario at reducing emissions was identified. Of the scenarios that were compared to the reference case, the one where 50 % of the electricity was produced from renewables in 2040 proved to be the most cost-efficient option. In addition, this scenario was also the most cost efficient at reducing emissions by a large margin. Regarding the renewable technologies, solar photovoltaics, which represented a majority of the renewable electricity production, was evidently the most cost-efficient technology as well as the one with the highest potential for future implementation, followed by onshore wind power. Moreover, concentrating solar power and waste to energy were proven to have a lower potential. The conclusions drawn were that the city of El Alamein could get a substantial part of its electricity from renewables and that solar PV was the best technology for that purpose. The final conclusion was that there might exist great potential for renewable energy in Egypt. / Med ambitionen att försöka lindra konsekvenserna av vad som idag är en av människans största utmaningar, klimatförändringen, är syftet med denna minor field study att utvärdera förutsättningarna för förnyelsebara energitekniker i Egypten. Detta ligger i linje med en större ambition att erbjuda ren och prisvärd energi i enlighet med de globala hållbarhetsmålen. Fältstudien utfördes i Egypten och omfattade en ny stad under konstruktion, El Alamein, som förväntas hushålla fyra miljoner invånare. En fältstudie och tillhörande intervju kombinerades med en litteraturundersökning för att erhålla nödvändig information som sedan användes i modelleringen av energisystemet. Modelleringsverktyget OSeMOSYS användes för att erhålla den mest kostnadseffektiva energimixen för åren 2020 till 2040, baserat på ett flertal olika scenarier och tekniker. Den totala diskonterade kostnaden samt mängden utsläpp jämfördes mellan de olika scenarierna, och det mest kostnadseffektiva scenariot för att minska utsläpp identifierades. Av de scenarier som jämfördes med referensfallet, så var scenariot där förnyelsebara energitekniker stod för 50 % av elproduktionen år 2040 den mest kostnadseffektiva energimixen för att tillfredsställa behovet samt för att minska mängden utsläpp. Av de förnyelsebara energiteknikerna så visade sig solceller, som stod för en majoritet av den förnyelsebara produktionen, vara den mest kostnadseffektiva tekniken då den i samtliga förnyelsebara scenarier prioriterades av modellen. Därmed visade sig den vara den tekniken med högst potential för framtida implementationer, följt av landbaserad vindkraft. Koncentrerad solkraft i form av soltorn visade sig inte vara kostnadseffektiv då den inte bidrog till produktionen i något scenario. Avfallsförbränningen, som bidrog minimalt till energimixen, saknade tillgång till den mängd bränsle som hade krävts för att den skulle kunnat stå för en större andel av produktionen. Därmed konstaterades det att båda dessa teknologier hade en låg potential för framtida implementationer. De slutsatser som drogs var att staden El Alamein kunde få en betydande del av sin elektricitet från förnyelsebara energikällor samt att solceller var mest lämpad för det syftet då den var mest kostnadseffektiv. Utöver dessa så drogs slutsatsen att det kan finnas stor potential för förnyelsebar energi i Egypten.

Zusammenfassung Um die ehrgeizigen politischen Ziele zur Reduzierung der Treibhausgasemissionen im Stromsektor zu erreichen, stimmen alle relevanten Energieszenarien überein, dass Deutschland kurz- bis mittelfristig bis 2035 seine Kapazitäten zur Erzeugung erneuerbarer Energien massiv ausbauen muss. Deutschland ist dabei wie viele andere Länder auch stark von fluktuierenden erneuerbaren Energiequellen (fEE) abhängig, insbesondere von der Wind- und Solarenergie. Die Spezifika der Stromerzeugung von fEE stellen neue und besondere Herausforderungen an ein zuverlässiges Stromversorgungssystem der Zukunft. Entsprechend hat die Erforschung der technischen Optionen bei der Integration großer Anteile von fEE in das Stromnetz in den letzten Jahren stark an Interesse gewonnen. Allerdings scheinen Energieszenarien die mit der schnellen technologischen Entwicklung einhergehenden Integrationsoptionen bisher nicht korrekt abzubilden. In der vorliegenden kumulativen Dissertation wurden ausgewählte technische Optionen für die Integration erneuerbarer Energiequellen in das Stromnetz im Rahmen einer Fallstudie für Deutschland sowie ausgewählter Übertragungsnetze in Deutschland untersucht. Zur Identifizierung und Bewertung der Integrationsmöglichkeiten, widmete sich die Arbeit den vielversprechendsten technischen Integrationsoptionen in Form von i.) systemfreundliche Auslegung von Wind- und Solaranalgen; ii.) optimale Kapazitätsanteile von Wind- und Solaranlagen, iii.) der räumlichen Allokation und Bewertung von Windenergieanlagen in herkömmlicher als auch systemfreundlicher Auslegung; iv.) und dem Beitrag welchen die flexible Stromerzeugung aus Bioenergie als Ergänzung zu steigenden Anteilen an fEE erbringen kann. Es wurde ein Methodenmix zur Beantwortung dieser Forschungsfragen genutzt, der von der numerischen Optimierung auf Basis von Zeitreihendaten über die räumliche Potenzialkartierung und Allokation bis hin zur multikriteriellen Entscheidungsanalyse reicht. Die Ergebnisse zeigen wie der Übergang zu einem von hohen Anteilen an vRES gekennzeichneten Stromversorgungssystem erleichtert werden kann. Darunter Möglichkeiten zur Beschleunigung des Umstiegs auf erneuerbare Energien mit deutlich reduzierten Erzeugungskapazitäten von Wind- und Solaranlagen, weniger negative Residuallasten und negativer residualer Energie, verbesserte Sektorenkopplung und die Potenziale der flexiblen Stromerzeugung aus Bioenergie als Ergänzung zu fEE.:Table of Contents Abstract Zusammenfassung Acknowledgements List of Publications List of Acronyms Table of Contents I. Introductory chapters 1. Introduction 1.1. Background 1.2. vRES in energy scenarios 1.3. Technical developments and options for the integration of vRES 2. Research questions 3. Methods applied in this PhD thesis 4. Discussion and conclusion 4.1. Summary of the main findings 4.2. Transferability of results and methods 4.3. Relevance and outreach 5. Appendix 6. Literature 7. Appended publications and the individual contribution to the publications 8. Curriculum Vitae (deleted) 9. Selbstständigkeitserklärung / Abstract: For Germany to achieve its ambitious political targets for the reduction of greenhouse gas emissions in the electricity sector, major energy scenarios and reports project that the country will have to expand its renewable power generation capacities massively by 2035. As is the case for many countries, Germany will have to heavily rely on variable renewable energy sources (vRES), especially wind and solar photovoltaics. The characteristics of power production from vRES pose challenges for a stable and reliable future power supply system. Accordingly, the research into the technical challenges of integrating large shares of vRES into the power system has therefore attracted much interest in recent years; however, major energy scenarios seem to not cover integration options associated with the fast development of vRES correctly and lag behind the fast development in renewable energy technology. In this cumulative thesis, selected technical options for the integration of renewable energy sources into the power supply system have been investigated in a case study of Germany and a selected transmission system in Germany. To identify and assess these emerging integration options, the research in this PhD thesis covers the most promising technical options for the integration of vRES in the form of i) system-friendly layouts of wind and solar PV; ii) optimal capacity mixes of vRES; iii) the spatial allocation of wind turbines and the impact assessment of wind turbine allocation; and iv) the contribution of flexible power generation from biomass to complement vRES. Therefore, a mix of methods has been applied, ranging from numerical optimization based on time series data, GIS potential mapping and allocation including a multi-criterial decision analysis. The results show how the investigated options can facilitate the transition for a power supply system dominated by high shares of vRES in the near to medium term. A faster energy transition with significantly reduced overall vRES power generation capacities, less Excess Energy (EE) generation, improved cross-sectorial energy provision and flexible bioenergy as a complement to vRES are the major findings of the investigated options in this thesis.:Table of Contents Abstract Zusammenfassung Acknowledgements List of Publications List of Acronyms Table of Contents I. Introductory chapters 1. Introduction 1.1. Background 1.2. vRES in energy scenarios 1.3. Technical developments and options for the integration of vRES 2. Research questions 3. Methods applied in this PhD thesis 4. Discussion and conclusion 4.1. Summary of the main findings 4.2. Transferability of results and methods 4.3. Relevance and outreach 5. Appendix 6. Literature 7. Appended publications and the individual contribution to the publications 8. Curriculum Vitae (deleted) 9. Selbstständigkeitserklärung

The 2050 national energy scenarios as planned by the DECC, academia and industry specify a range of different decarbonised supply side technologies combined with the electrification of transportation and heating. Little attention is paid to the household demand side; indeed within many scenarios a high degree of domestic Demand Side Management (DSM) is implicit if the National Grid is to maintain supply-demand balance. A top-down, bottom-up hybrid model named Shed-able Household Energy Demand (SHED) has been developed and the results of which presented within this thesis. SHED models six published national energy scenarios, including three from the Department for Energy and Climate Change, in order to provide a broad coverage of the possible energy scenario landscape. The objective of which is to quantify the required changes in current household energy demand patterns via DSM, as are implicit under these highly electricity dominated scenarios, in order to maintain electrical supply-demand balance at the national level. The frequency and magnitude of these required household DSM responses is quantified. SHED performs this by modelling eleven years of supply-demand dynamics on the hourly time step, based on the assumptions of the published energy scenarios as well as weather data from around 150 weather stations around the UK and National Grid historic electricity demand data. The bottom-up component of SHED is populated by 1,000 households hourly gas and electricity demand data from a recently released dataset from a smart metering trial in Ireland. This aggregate pool of households enables national domestic DSM dynamics to be disaggregated to the aggregate household level. Using household classifications developed by the Office for National Statistics three typical ' households are identified within the aggregate pool and algorithms developed to investigate the possible required responses from these three households. SHED is the first model of its kind to connect national energy scenarios to the implications these scenarios may have on households consumption of energy at a high temporal resolution. The analysis of the top-down scenario modelling shows significant periods where electrical demand exceeds supply within all scenarios, within many scenarios instances exist where the deficit is unserviceable due to lack of sufficient spare capacity either side of the deficit period. Considering the level of participation required within the modelled scenarios in order to balance the electricity system and the current lack in understanding of smart metering and Time-Of-Use (TOU) tariffs within households, it would seem there is a disconnect between the electricity system being planned, the role this system expects of households and the role households are willing to play.

As part of efforts to curb the protracted electricity problem in Nigeria, the government enacted the National Renewable Energy and Energy Efficiency Policy (NREEEP) in 2014. Through this policy, the country plans to increase its electricity generation from renewables to 20% by 2030. This thesis investigates the economic feasibility of this lofty goal, and as well determine the best hybrid configuration for off-grid rural/remote power generation across the six geopolitical zones of Nigeria The economic feasibility results, using Long-range Energy Alternative Planning (LEAP) tool, show that the 20% renewables goal in the Nigerian power generation mix by 2030 is economically feasible but will require vast investment, appropriate supportive mechanisms, both fiscal and non-fiscal (especially for solar PV) and unalloyed commitment on the part of the government. Moreover, the techno-economic results with Hybrid Optimization Model for Electric Renewable (HOMER) reveal Small hydro/Solar PV/Diesel generator/Battery design as the most cost-effective combination for power supply in remote/rural areas of Nigeria. Findings also highlight the better performance of this system in terms of fuel consumption and GHGs emission reduction. Lastly, the study identifies factors influencing RE development, and offers strategic and policy suggestions to advance RE deployment in Nigeria.

Durch den Ausbau an Wind- und PV-Anlagen in Deutschland wird der Flexibilitätsbedarf im Stromsystem steigen. Der Flexibilitätsbedarf kann zum einen durch verschiedene Technologien, z.B. Speicher oder Netze, und zum anderen durch die Stromnachfrage bereitgestellt werden. Eine gezielte Steuerung der Stromnachfrage wird als Demand Side Management (DSM) bezeichnet. Der zunehmend wetterabhängigen und fluktuierenden Stromerzeugung in Deutschland steht jedoch eine bis heute weitgehend unelastische Nachfrage gegenüber. In der Literatur sind verschiedene Arbeiten zu finden, die das Potential zur Lastabschaltung und verschiebung in Deutschland untersuchen. Hierbei liegt der Fokus auf absoluten Werten. Saisonale oder tageszeitliche Unterschiede bleiben dabei häufig unberücksichtigt. Die vorliegende Dissertation greift an dieser Stelle an und untersucht das Potential ausgewählter DSM-Anwendungen in stündlicher Auflösung. Die Ergebnisse zeigen, dass das verfügbare Potential starken saisonalen und tageszeitlichen Schwankungen unterliegt. Dementsprechend wird das DSM-Potential überschätzt, wenn nur absolute Werte betrachtet werden. Darüber hinaus zeigt die Autorin, welche Entwicklungen in den nächsten Jahren hinsichtlich der Verfügbarkeit des DSM-Potentials zu erwarten sind. Basierend auf der Potentialermittlung wird in der Dissertation die Rolle von DSM in einem EE-geprägten Stromsystem modellbasiert untersucht. Hierfür wird das lineare Optimierungsmodell ELTRAMOD, das den deutschen und europäischen Strommarkt abbildet, weiterentwickelt. Anhand verschiedener Szenarien wird zum einen der Beitrag von DSM zur Systemintegration von erneuerbaren Energien in Deutschland und zum anderen die Wechselwirkungen mit anderen Flexibilitätsoptionen (z.B. Speicher) untersucht. Die Ergebnisse zeigen, dass die DSM-Kategorien Lastabschaltung und verschiebung nur kurzzeitig auftretende Schwankungen der Einspeisung aus erneuerbaren Energien ausgleichen können. Zum Ausgleich großer Überschussmengen aus erneuerbaren Energien sind hingegen Power-to-X-Technologien, z.B. Power-to-Heat, besser geeignet.