The society is going through transformations in several dimensions at the same time. The energy system is moving towards renewables and reduced resource intensity. Market structures are gradually changing, and new actors emerge to compete with incumbents. Digitization creates fundamentally new conditions for everyone. Cities are being reimagined and are driving much of the transformation. Energy optimization becomes a heated topic for the whole society. This thesis research collaborated with the company SWECO Energy Strategies group investigates one part of energy optimization: proposing different possible scenarios of combining different types of buildings in a city block to urban designers and real estate company. The objective of this research is to find out the suitable combinations leading to an evener and lower demand profile from the perspectives of energy supply and the grid. This thesis project will try different methods to identify the most promising combination of various functioned buildings and develop a new methodology to solve the similar cases. A city block with either several types of building or single type of building can have an even and low energy profile. Moreover, there isn’t a definite relationship between the flatness of energy profile and the correlated amount of total demand. In this project, different scenarios are created and tested by the assistance of Python programing language and Solver installed in Excel. Through a series of tests and analysis, the best case is found with the most area of residential buildings. Qualitatively economic analysis is done, proving that an even energy profile is conducive to the cost-saving. Through the conducted case study, a general methodology is developed, which facilitates urban designers to design similar projects to some extent in the future.

Klimatförändring ställer idag krav på högre energieffektivitet vilket lett till utbyggnaden av ett distribuerat energisystem. Samtidigt introduceras framväxande teknologier som digitala tvillingar till det nya energisystemet i hopp om att ytterligare effektivisera systemet. För att främja samarbete mellan industrin och akademin, och således stödja utvecklingen och implementeringen av digitala tvillingar, bör aktörernas syner sammanföras. Syftet med arbetet är därav att undersöka ifall det finns några likheter och skillnader mellan industri och akademi i hur de uppfattar användningsområdena och utmaningarna med digitala tvillingar av distribuerade energisystem. För att besvara forskningsfrågan utfördes inledningsvis en systematisk litteraturstudie. Studien utgör arbetets underlag för akademins uppfattning om digitala tvillingars användningsområden och utmaningar. Vidare utfördes fem intervjuer med olika industriaktörer med insikt i digitala tvillingar och distribuerade energisystem för att avgöra deras uppfattning om teknologin. Insikterna från litteraturstudien och intervjuerna ställdes sedan mot varandra för att identifiera eventuella likheter och skillnader. De användningsområden som identifierades av akademin och industrin var simulering, felidentifiering och prediktivt underhåll, visualisering och styrning, cybersäkerhet, optimering av kraftnätet samt prognostisering och estimering. Utmaningarna som identifierades av akademin var standardiserade ramverk för modellering och för datahantering, brist på passande sensorer, datalagringsmöjligheter, datorers beräkningskapacitet och cyberattacker. Industrin identifierade motstånd till ny teknologi, kompetensbrist, silotänk, teknologins värdeskapande, datahantering och cyberattacker som huvudutmaningarna med digitala tvillingar. Utifrån analysen har industrin och akademin en liknande uppfattning om digitala tvillingars användningsområden inom distribuerade energisystem men uppfattningen om utmaningarna med digitala tvillingar var, inom akademin, mer teknikbaserad medan den inom industrin var främst icketeknisk. / Today, the increasing threat of climate change has created a greater need for higher energy efficiency, which has led to the development of a distributed energy system. At the same time, emerging technologies such as digital twins are being introduced into the new energy system in the hope of further improving the efficiency of the system. To promote cooperation between industry and academia, and thus support the development and implementation of digital twins, the views of the actors should be brought together. The purpose of this work is therefore to investigate whether there are any similarities and differences between industry and academia in how they perceive the applications and challenges of digital twins of distributed energy systems.  To answer the research question, a systematic literature study was initially conducted. The study constitutes the basis for the academia's perception of the use cases and challenges of digital twins. Furthermore, five interviews were conducted with different industrial actors with insight into digital twins and distributed energy systems to determine their perception of the technology. The insights from the literature study and interviews were then compared to identify any similarities and differences.  The application areas identified by academia and industry were simulation, fault identification and predictive maintenance, visualization and control, cyber security, grid optimization, and forecasting and estimation.  The challenges identified by academia were standardized modelling and data management frameworks, lack of suitable sensors, data storage capabilities, computational capacity of computers and cyber-attacks. Industry identified resistance to new technologies, skills shortages, silo thinking, technology value creation, data management and cyber-attacks as the main challenges of digital twins. Based on the analysis, industry and academia have a similar perception of the use cases of digital twins of distributed energy systems but the perception of the challenges of digital twins was, in academia, more technology-based while in industry it was mainly non-technical.

This thesis studies preconditions for clean hydrogen energy deployment in energy systems of Spain, Sweden, The UK, and China, considering these countries' geographical, political, and economic peculiarities. Countries' readiness for hydrogen energy uptake assessment is based on a comprehensive analysis of energy systems in selected countries by taking an integrated whole-system approach analyzing hydrogen supply in different infrastructure configurations as well as hydrogen transportation and storage and hydrogen use in the energy ecosystem. The readiness index of each country is evaluated in technological, political, societal, and economic dimensions, which are interdependent and influence not only each other, but the entire outcome of the energy transition phenomena studied in this thesis. The analysis concludes that the political dimension is the dominant one, as the government has the power to steer finance toward a green transition, making the desired change, such as clean hydrogen energy industry formation in the country, happen. Current energy transition entails economic and institutional change and deep industrial restructuring, all of which require specific policy instruments and conditionalities, balancing risks and behaviours in the process of the energy transition. Based on the results of this study, the UK and China have the highest political readiness among the analyzed countries, which also results in their higher economic, technology, and societal readiness levels.

Integrating energy across different sectors is an efficient solution for improving energy systems to meet energy demands with low CO2 emissions. Such integration includes combining the supply and demand of heating, cooling, and electricity by implementing appropriate equipment, as well as combining the energy systems of civic and industrial sectors. This thesis develops various optimization approaches to identify the optimal design and operation of distributed energy systems and the integration of energy systems across commercial, industrial, and transportation sectors, which minimize CO2 emissions and costs of the systems. Available equipment of the energy systems includes combined cooling, heating, and power system, absorption chiller, solar thermal collector, photovoltaic, boiler, electric chiller, battery, ground source heat pump, and air source heat pump. This thesis provides the following contributions to this area. (1) Identify optimal structures of distributed energy systems under different electric grid CO2 footprints. The work implements representative periods when formulating the energy system, which reduces computation time. (2) Differentiate heating demands of entities in the integrated system at different temperature levels to ensure feasible heat transfer. It removes the simplified assumptions in existing studies on the integrated energy system that assume all heating demands are at a uniform temperature. (3) Optimize production rates of plants instead of assuming steady industrial production rates. The switchable production rates lead to a further reduction in CO2 emissions of the integrated system. (4) Identify the environmental and economic benefits of the integrated operation under different electric grid CO2 footprints. It presents that integrated operation reduces more CO2 emissions when the electric grid has higher CO2 footprints. (5) Identify the optimal relative sizes of entities in the integrated system that maximize the CO2 emissions reduction benefits brought by the integrated system. (6) Prove the integrated system has lower CO2 emissions than individual energy systems both under deterministic and stochastic scenarios. Overall, the work in this thesis contributes to developing energy systems and integrated energy systems with the lowest possible CO2 emissions under various scenarios. / Thesis / Doctor of Philosophy (PhD) / As the total population continues to increase worldwide, it is necessary to improve community energy systems to reduce CO2 emissions when meeting energy demands. An efficient solution is integrating energy systems across different sectors. This work explores novel structures of energy systems – integrated energy systems that combine the supply and demand of heating, cooling, and electricity in residential, commercial, industrial, and transportation sectors. The optimal energy system configurations, sizes of subsystems, production rates of plants, heat transfer and electricity transfer, as well as capacity and operation of the equipment, have been identified by developing optimization approaches that minimize CO2 emissions and costs of the integrated system. The optimal design and operation are found under both deterministic and stochastic scenarios and different grid electricity generation scenarios, which provide references for developing community energy systems with the lowest possible CO2 emissions under various scenarios.

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.

Municipalities globally are recognizing their role in mitigating climate change and are actively working to reduce carbon emissions. This complex challenge is heightened in areas like Northern Sweden, where municipalities are adapting to accommodate new industries essential for meeting global climate targets, subsequently changing the energy landscape. The local administration must not only decarbonize existing energy use but also develop infrastructure for the new industries, all while fostering sustainable and appealing cities where residents aspire to live. However, the trajectory of these changes and the subsequent future energy requirements remain uncertain. This study aims to assist the local administration in navigating through these uncertainties and setting ambitious climate and energy targets aligned with the goals of the Paris Agreement and sustainable developments. The research explores how model based scenario analysis can be improved to identify a set of relevant pathways that the municipalities can adopt by employing system analysis, energy system optimization, and scenario analysis. The study focuses on Gällivare municipality in Northern Sweden and employs the TIMES-City model to develop the energy system model of the municipality (RQ1). To identify relevant scenarios for local energy transition a framework for developing "Glocal" scenarios has been established (RQ2). These glocal scenarios incorporate global, national, and local socioeconomic trends into a coherent narrative and provide a more holistic and realistic view of potential future pathways (Paper 2). Additionally, a set of SDG indicators for evaluating the sustainability of different scenarios has been developed and applied in the model (RQ3, Paper 3). While the study focuses on Gällivare, the "glocal" scenario framework and SDG indicators developed in this research can be utilized by municipalities across the globe for identifying their climate and energy targets.

Transportation is embedded in the fabric of society and a key enabler of socio-economic development, but it is also a major source of carbon dioxide (CO2) and local air pollution (AP). Cities collectively account for around three quarters of total energy-related CO2 emissions, and the negative health impacts from local APs are most felt in dense urban environments. Thus, transitioning away from current fossil fuel regime in urban transportation is necessary to address both global and local challenges. Mathematical models as energy system optimisation models (ESOMs) are commonly applied to explore contrasting energy futures and to provide insights on how the energy system (or specific sub-sectors) may evolve under different conditions. However, ‘typical’ national level models are not fully adapted to capture the characteristics of local (city) transportation, and previous city-level ESOM based analyses have focused on decarbonisation of local energy systems, thus omitting other local policy considerations as e.g. air quality, and several studies excluded transportation altogether.  In this thesis, a generic city-level ESOM framework (TIMES-City) was further adapted and used to provide policy-relevant insights on the anticipated energy transition of the local transport sector. The underlying work rests on a systems analysis approach, building on careful consideration of the overall system performance and boundaries, understanding of specific system characteristics, and challenges and opportunities facing local ‘system managers’; this has implications for model representation and for quantitative and qualitative modelling assumptions. Further, availability and quality of local transport, energy and emission data needed to calibrate models poses significant challenges, and considerable effort was also put on producing projections for future transport demand (a key model input), using lessons and input data from traditional transport demand models. These considerations were addressed in Paper I.  The model was then applied to two different cases (in Sweden) to explore potential conflicts and co-benefits between ambitious climate targets and deep cuts in APs (Paper II), and to assess the roles of local and regional governments in CO2 mitigation when also considering ambitious national-scale policies (Paper III). The results of Paper II indicate that substituting fossil fuels for biofuels in conventional vehicles is the least-cost decarbonisation pathway, however this produces only minor or even negative benefits to air quality. While, zero-emission vehicles cut all local tail-pipe emissions, but their total impact on climate change mitigation is determined by upstream impacts from the conversion and distribution of energy carriers. Thus, ensuring low levels of total CO2 and APs from transportation calls for re-coupling of the local and global responsibilities and motivations into comprehensive mitigation strategies. The results of Paper III indicate that current Swedish national mitigation measures will drive down CO2 emissions in transportation considerably, but biofuel availability and BEV (battery electric vehicles) costs are critical for the rate and extent of the transition, while locally and regionally determined measures to enable shifts (from car) to active travelling, public transportation and home-based work have a much more limited direct impact. Nonetheless, these measures, along with city investments in BEVs and charging infrastructure which pave the way also for residents and local businesses, can help to reduce overall energy intensity of the transport sector, thus slowing down growth in fuel demand and contribute to reaching ambitious climate targets with limited renewable resources (as e.g. biofuels). The two studies (Papers II and III) illustrate the usefulness of applying comprehensive ESOMs also at sub-national levels, providing insights on both global and local sustainability implications as well as deeper understanding of the roles of local and regional decision-makers in enabling and supporting low-carbon transitions in transportation.

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Water stress is an ongoing problem in many places in the world, while the demand for clean and safe freshwater is growing due to the increasing population. In many developing countries, water supplies often are contaminated with arsenic, fluoride, etc. Therefore, it is important to realize that water scarcity and contamination issues concern only one sector but many. HVR Water Purification AB is developing a water purification prototype – ELIXIR 500 - using the air gap membrane technology and is implemented in Odisha, India, aiming to supply with 200 litre water daily. This thesis aims to estimate future energy sources to supply this prototype and explore the possibilities of using only renewable energy resources from technical, economic, and environmental perspectives. These are achieved by firstly identifying the energy possibilities in Odisha, India, and then calculating the feasibility of each solution chosen and finally analyzing the results. Among the energy sources, which are power grid, wind and solar power, diesel generator and solar-diesel hybrid system. It is found that the energy source to the prototype supplied by the power grid is 0.057 USD per litre water, which is the cheapest option. However, it is not feasible due to the lack of electrification from the local network. Meanwhile, the solar-diesel hybridized energy system is the most economical option if renewable energy sources are integrated with 0.11 USD per litre water. / Vattenstress ett pågående problem på många ställen i världen medan efterfrågan på rent och säkert dricksvatten växer på grund av den ökande befolkningen. I många utvecklingsländer är vattenförsörjningen ofta förorenade med arsenik, fluor osv. Det är därför viktigt att inse att vattenbrist och föroreningar inte bara rör en sektor utan många. HVR Water Purification AB utvecklade en prototyp för vattenrening - ELIXIR 500 - med hjälp av luftspaltmembrantekniken (eng: air gap membrane distillation och implementeras redan i Odisha, Indien, med målet att förse 200 liter rent vatten dagligt. Denna avhandling syftar till att uppskatta de framtida energikällorna för att tillhandahålla denna prototyp och utforska möjligheterna att endast använda förnybara energikällor ur tekniska, ekonomiska och miljömässiga perspektiv. Dessa uppnås genom att först identifiera de olika energimöjligheter i Odisha, Indien, följt av beräkningar om utförbarhet för varje vald lösning och slutligen en analys av resultaten. Bland energikällorna elnät, vind, sol, diesel generator och sol-diesel hybrid system har visat sig att energikällan till prototypen som levereras av elnätet som kostar 0.057 USD per liter vatten som det billigaste alternativet, men det är inte möjligt på grund av bristen på elektrifiering från det lokala elnätet. Å andra sidan är det hybridiserade energiskombinationen med solkrafts och diesel det billigaste alternativet om förnybara energikällor ska integreras, resultatet visade att vara 0.11 USD per liter vatten.