Climate change is no longer imminent but eminent. To combat climate change, effective, efficient and smart energy use is imperative. Thermal energy storage (TES) with phase change materials (PCMs) is one attractive choice to realize this. Besides suitable phase change temperatures and enthalpies, the PCMs should also be robust, non-toxic, environmental-friendly and cost-effective. Cost-effective PCMs can be realized in bulk blends. Blends however do not have robust phase change unless chosen articulately. This thesis links bulk blends and robust, cost-effective PCMs via the systematic design of blends as PCMs involving phase equilibrium evaluations. The key fundamental phase equilibrium knowledge vital to accurately select robust PCMs within blends is established here. A congruent melting composition is the most PCM-ideal among blends. Eutectics are nearly ideal if supercooling is absent. Any incongruent melting composition, including peritectics, are unsuitable as PCMs. A comprehensive state-of-the-art evaluation of the phase equilibrium-based PCM design exposed the underinvestigated categories: congruent melting compositions, metal alloys, polyols and fats. Here the methods and conditions essential for a comprehensive and transparent phase equilibrium assessment for designing PCMs in blends are specified. The phase diagrams of the systems erythritol-xylitol and dodecane-tridecane with PCM potential are comprehensively evaluated. The erythritol-xylitol system contains a eutectic in a partially isomorphous system unlike in a non-isomorphous system as previous literature proposed. The dodecane-tridecane system forms a probable congruent minimum-melting solid solution, but not a maximum-melting liquidus or a eutectic as was previously proposed. The sustainability aspects of a PCM-based TES system are also investigated. Erythritol becomes cost-effective if produced using glycerol from bio-diesel production. Olive oil is cost-effective and has potential PCM compositions for cold storage. A critical need exists in the standardization of methods and transparent results reporting of the phase equilibrium investigations in the PCM-context. This can be achieved e.g. through international TES collaboration platforms. / Energi är en integrerad del av samhället men energiprocesser leder till miljöbelastning, och klimatförändringar. Därför är effektiv energianvändning, ökad energieffektivitet och smart energihantering nödvändigt. Värmeenergilagring (TES) är ett attraktivt val för att bemöta detta behov, där ett lagringsalternativ med hög densitet är s.k. fasomvandlingsmaterial (PCM). Ett exempel på ett billigt, vanligt förekommande PCM är systemet vatten-is, vilket har använts av människor i tusentals år. För att tillgodose de många värme- och kylbehov som idag uppstår inom ett brett temperaturintervall, är det viktigt med innovativ design av PCM. Förutom lämplig fasförändringstemperaturer, entalpi och andra termofysikaliska egenskaper, bör PCM också ha robust fasändring, vara miljövänlig och kostnadseffektiv. För att förverkliga storskaliga TES system med PCM, är måste kostnadseffektivitet och robust funktion under många cykler bland de viktigaste utmaningarna. Kostnadseffektiva PCM kan bäst erhållas från naturliga eller industriella material i bulkskala, vilket i huvudsak leder till materialblandningar, snarare än rena ämnen. Blandningar uppvisar dock komplexa fasförändringsförlopp, underkylning och/eller inkongruent smältprocess som leder till fasseparation. Denna doktorsavhandling ger ny kunskap som möjliggör att bulkblandningar kan bli kostnadseffektiva och robusta PCM-material, med hjälp av den systematiskutvärdering av fasjämvikt och fasdiagram. Arbetet visar att detta kräver förståelse av relevanta grundläggande fasjämviktsteorier, omfattande termiska och fysikalisk-kemiska karakteriseringar, och allmänt tillämpliga teoretiska utvärderingar. Denna avhandling specificerar befintlig fasjämviktsteori för PCM-sammanhang, men sikte på att kunna välja robusta PCM blandningar med specifika egenskaper, beroende på tillämpning. Analysen visar att blandningar med en sammansättning som leder till kongruent smältande, där faser i jämvikt har samma sammansättning, är ideala bland PCM-blandningar. Kongruent smältande fasta faser som utgör föreningar eller fasta lösningar av ingående komponenter är därför ideala. Eutektiska blandningar är nästan lika bra som PCM, så länge underkylning inte förekommer. Därmed finns en stor potential för att finna och karakterisera PCM-ideala blandningar som bildar kongruent smältande föreningar eller fasta lösningar. Därigenom kan blandningar med en skarp, reversibel fasändring och utan fasseparation erhållas – egenskaper som liknar rena materialens fasändringsprocess. Vidare kan man, via fasdiagram, påvisa de blandningar som är inkongruent smältande, inklusive peritektiska blandningar, som är direkt olämpliga som PCM. Denna avhandling ger grundläggande kunskap som är en förutsättning för att designa PCM i blandningar. Genom en omfattande state-of-the-art utvärdering av fas-jämviktsbaserad PCM-design lyfter arbetet de PCM-idealiska blandningarna som hittills inte fått någon uppmärksamhet, såsom kongruenta smältande blandningar, och materialkategorierna metallegeringar, polyoler och fetter. Resultatet av arbetet visar dessutom att vissa PCM-material som ibland föreslås är direkt olämpliga då fasdiagram undersöks, bl a pga underkylning och även peritektiska system med fasseparation och degradering av kapaciteten (t ex Glauber-salt och natriumacetat-trihydrat). Denna avhandling specificerar och upprättar grundläggande teori samt tekniker, tillvägagångssätt och förhållanden som är nödvändiga för en omfattande och genomsynlig fasjämviktsbedömning, för utformning av PCM från blandningar för energilagering. Med detta som bas har följande fasdiagramtagits fram fullständigt: för erytritol-xylitol och för dodekan-tridekan, med PCM-potential för låg temperaturuppvärmning (60-120 °C) respektive frysning (-10 °C till -20 °C) utvärderas fullständigt. Erytritol-xylitol systemet har funnits vara eutektiskt i ett delvis isomorft system, snarare än ett icke-isomorft system vilket har föreslagits tidigare litteratur. Dodekan-tridekan systemet bildar ett system med kongruent smältande fast lösning (idealisk som en PCM) vid en minimumtemperatur, till skillnad från tidigare litteratur som föreslagt en maximumtemperatur, eller ett eutektiskt system. Teoretisk modellering av fasjämvikt har också genomförts för att komplettera det experimentella fasdiagrammet för systemet erytritol-xylitol. Efter granskning av de metoder som använts tidigare i PCM-litteraturen har här valts ett generiskt tillvägagångssätt (CALPHAD-metoden). Denna generiska metod kan bedöma vilken typ av material och fasändring som helst, till skillnad från en tidigare använda metoder som är specifika för materialtyper eller kemiska egenskaper. Denna teoretiska studie bekräftar termodynamiskt solvus, solidus, eutektisk punkt och erytritol-xylitol fasdiagrammet i sin helhet. Vad gäller hållbarhetsaspekter med PCM-baserad TES, lyfter denna avhandling fokus på förnybara och kostnadseffektiva material (t.ex. polyoler och fetter) som PCM. Som exempel har här undersökts erytritol och olivolja, med förnybart ursprung. Erytritol skulle kunna bli ett kostnadseffektivt PCM (163 USD/kWh), om det produceras av glycerol vilket är en biprodukt från biodiesel/bioetanolframställning. Olivolja är ännu ett kostnadseffektivt material (144 USD/kWh), och som här har påvisats innehålla potentiella PCM sammansättningar med lämpliga fasändringsegenskaper för kylatillämpningar. En övergripande slutsats från denna avhandling är att det finns ett behov av att standardisera tekniker, metoder och transparent resultatrapportering när det gäller undersökningar av fasjämvikt och fasdiagram i PCM-sammanhang. Internationella samarbetsplattformar för TES är en väg att koordinera arbetet. / <p>QC 20170830</p>

The purpose of this bachelor thesis is to assess whether it is possible to create a simplified model that estimates the hosting capacity of a low-voltage grid. The Simplified model is compared with a more elaborate model created by the Built Environment Energy Systems Group (BEESG) at Uppsala University. The Simplified model takes three easily obtainable variables into account. The model created by BEESG allows us to observe both the amount of photovoltaic (PV) power that is installed as well as the voltages in each bus in a grid. The hosting capacity is found by gradually increasing the amount of PV power installed in a low-voltage grid until overvoltage is reached. Simulations with BEESG’s model are done for a week in July when the PV generation has its peak and the load is generally low. The Simplified model is created using linear regression with the calculated values from the BEESG’s model as a reference. The report shows that the Simplified model will give an estimation of the low-voltage grid’s hosting capacity that is comparable to the value calculated with BEESG’s model. The results show that it is rarely the low-voltage grid that restricts the installation of PV facilities and that a high self-consumption is advantageous regarding to the grids hosting capacity.

One of the main social challenges that society is facing nowadays is the energy crisis. So, head towards renewable energy resources such as solar, hydraulic, wind, geothermal and biomass, could be the best solution. Solar photovoltaic is one of the most promising sources to produce electricity due to its cleanness, noiselessness and sustainability, and the fact that it is inexhaustible. However, the power output of the PV systems varies notably because of the ambient conditions: temperature and solar radiation. The main aim of this thesis is to study if the PV system installed on the wall of the new football arena Gavlehov in Gävle is providing the amount of power promised before the installation. To achieve reliable results, the first step is to develop and install a monitoring system for recording the real power of the system and the ambient conditions at the same time. After that, an evaluation of the performance of the system during one week will be done, comparing the theoretical power and the real power obtained. The theoretical power will be calculated in two ways: using the data from a pyranometer and on the other hand, from a reference solar cell. This will permit to compare which one matches better with the reality. Different factors such as the temperature, the irradiance and the angle of incidence are studied to know the real influence that they have on the performance of a PV installation. The results obtained show that the measurement system installed is reliable and that the model used to evaluate the system is correct. It can be concluded that using a reference solar cell to calculate the theoretical power of the system is easier to align and it has the same angular behaviour as a PV module than employing a pyranometer. Regarding the installation, all the panels work similarly and the system works at nominal power. So, it provides the amount of power promised before the installation. Key words: Renewable energy, PV system, solar radiation, nominal power, pyranometer, solar cell.

Packaging has been on the environmental agenda for decades. It has been discussed and debated within the society mainly as an environmental problem. Production, distribution and consumption of food and drinks contribute significant to the environmental impact. However, consumers in the EU waste about 20% of the food they buy. The function of packaging in reducing the amount of food losses is an important but often neglected environmental issue. This thesis focuses on the functions of packaging that can be used to preserve resources efficiently and reduce the environmental impact of the food-packaging system. The service perspective is used to increase knowledge about consumer interaction with packages. Fifteen packaging attributes, for example, ‘easy to empty’, ‘hygienic’ and ‘contain the right quantity’, were identified as influencing the amount of food losses at the consumer. The result showed that there are potentials to both increase consumer satisfaction and decrease the environmental impact of the food-packaging system, when new packaging design reduces food losses. A model was developed that calculates the balance of environmental impact between reduction of food losses, and more packaging material. The result showed that it can be environmentally motivated to increase the environmental impact of packaging, if the amount of food losses is reduced. This is especially true for food items with high environmental impact, e.g. meat and dairy products, and for food items that have a high share of loss, e.g. bread. I have also explored to what extent packaging can influence food losses in households. The study showed that about 20% to 25% of household food waste was related to packaging. The households noted three packaging attributes as the main causes for food losses; ‘too big packaging’, ‘difficult to empty’ and ‘best-before-date’. Finally there is a discussion of packaging research in the context of sustainability principles, and suggestions for further research. / <p>Paper IV was still a manuscript at the time of the thesis defense.</p>

This report shows the study performed at Taipei National University of Technology in Taipei to evaluate the performance of a solar air conditioning system. The performance is evaluated under Taiwan climate conditions. The research is performed under summer weather conditions. No influence is done on these conditions. A solar air conditioning system currently available on the market is used. No changes are made to the system. The work to be done is divided into different phases in order to guide the process. First, a literature research is done to find similar research done on this topic and to gain a basic understanding of the topic. Then several measurement plans are made to investigate different parts of the system.. Measurements are done. It is tried to developing a computer model in order to be able to simulate the system performance. The overall objective was to gain knowledge about a solar assisted air-conditioning system and develop a model to simulate the system. Initially a list of research questions was made in order to quantify ‘gaining knowledge’ about the system. The plan was to answer them by using measurement data and creating a model to perform simulations. There are measurements done in this report, however due to too many ‘unknowns’* it is difficult to draw conclusions from them. A lot of research questions are still open and they are also not included in this report. It is also not succeeded to make a working model of a solar assisted air conditioner. It is succeeded in making a model to predict the performance of the evaporator. This model is currently within 11% accurate.

Swedish state has been promoting alternative renewable fuels like biogas to reduce the dependency on fossil fuels and to curb related greenhouse gas emissions. Owing to many policies like subsidies and tax exemptions for using biogas, the country has seen a surge in demand for biogas. Meanwhile, the increase in production of biogas in Sweden has been modest in recent years, though many studies have estimated substantially higher potentials from many sources. Agricultural feedstock/biomass is one among these sources where production and use of biogas could address many challenges faced by farmers like agricultural waste management, soil nutrient management, methane emissions from manure etc. while closing the nutrient cycle and contributing to sustainability.This work is an investigation on how to stimulate the growth of biogas production based on agricultural feedstock/biomass production in Sweden. Since policies give different results in different states/countries depending on the local preconditions, locally developed policies, national policies and EU policies should integrate well in all the policy sectors in that particular region to give the intended result. The current production capacity is about 2 TWh worth of biogas/year but the theoretical potential is estimated to be up to 15 TWh that has been claimed by many researches and literature works like in (Westlund, et al., 2019). Much of the potential has not been explored especially in the field of agriculture. It is asserted in many articles that the true potential of biogas production from Swedish agriculture is far greater than what is produced today. Yet, all the regulations, financial and other financial instruments failed to stimulate local biogas production in Sweden to attain its full theoretical potential. The results presented in this study show where these policies failed and what else apart from the policies could be improved in order promote biogas production.Farmers are hesitant to invest in biogas production because of the complexity and unpredictability of the existing policies. There has been significant negative impact from lack technological training of anaerobic digestion (AD) technology. This is also reflected as difficulties in finding trained and dedicated staff for biogas plant operations. Low profitability of biogas business exists ever since the production started and the financial aids are insufficient. Strict digestate regulations along with worsening substrate competition also creates problems. Permits to run the biogas plants are perceived to be expensive alongside increasing investment costs and taxes, affecting already low profitability. There is also a lack of infrastructure in terms of electricity/gas grid connectivity. Feed in tariffs for electricity produced from renewable sources are not bringing enough profitability to the business. Technological improvements are needed in terms of agricultural machinery that can use upgraded biogas as fuel and treatment of digestate to eliminate heavy metal content. Producers need more long term, sure market for their biogas. / Biogasmarknadsutredningen of BRC

Improving energy performance of existing buildings is an important part in decreasing energy use and in turn reduce the greenhouse gas emissions caused by human activity and the primary energy use. To be able to evaluate how energy refurbishment influences the greenhouse gas emissions and the primary energy use a wider system perspective is needed that puts the building in its context. This thesis deals with energy refurbishment packages performed on multi-family buildings within district heated areas and how they influence greenhouse gas emissions and primary energy use when the district heating use is altered. A simulated building is used to evaluate several energy refurbishment packages. The results are used as input data for models of district heating systems to cost optimize the district heating production. The results from the cost optimization are used to evaluate the impact on greenhouse gas emissions and primary energy use. The results show a difference between measures that saves district heating without increasing the use of electricity and measures that increases the use of electricity while district heating is saved. For example, a building refurbishment package including only building envelope improvements saves the same amount of district heating as a package including only mechanical ventilation with heat recovery. Despite this, the emissions of greenhouse gases and the use of primary energy is to a greater extent reduced in the first package because the use of electricity remains unchanged. Comparing energy refurbishment packages performed on the same building, but within different district heating systems, show the importance of the design of the district heating system. Depending on the fuel types used and to which extent electricity is co-produced in the district heating system, the results of implementing the energy refurbishment packages vary. The largest reduction of greenhouse gases and primary energy use occurs when a refurbishment package is performed on a building in a district heating system with high share of biofuel and no electricity production. / Att förbättra energiprestanda hos befintliga byggnader är en viktig del i arbetet med att minska energianvändningen och i sin tur minska utsläpp av växthusgaser orsakade av mänsklig aktivitet samt att minska användningen av primärenergi. För att kunna utvärdera hur energieffektivisering av byggnader påverkar växthusgasutsläpp och primärenergianvändning behövs ett brett systemperspektiv som sätter byggnaden i sitt sammanhang. Denna avhandling handlar om hur paket av energieffektiviseringsåtgärder som utförs på flerfamiljshus inom fjärrvärmeuppvärmda områden påverkar växthusgasutsläpp och primärenergianvändning när fjärrvärmeanvändningen förändras. Resultaten visar på skillnader mellan åtgärder som sparar fjärrvärme utan att öka användningen av el och åtgärder som ökar användningen av el medan fjärrvärme sparas. Till exempel sparar ett energieffektiviseringspaket som endast omfattar byggnadsskalsförbättringar samma mängd fjärrvärme som ett paket som endast omfattar installation av mekanisk ventilation med värmeåtervinning. Trots detta minskar utsläppen av växthusgaser och användningen av primärenergi i större utsträckning i det första paketet på grund av att elanvändningen förblir oförändrad. Vikten av fjärrvärmesystemets utformning visas då en byggnad där olika energieffektiviseringspaket testats, flyttas runt till olika fjärrvärmesystem. Beroende på vilka bränsletyper som används och i vilken utsträckning som el produceras i fjärrvärmesystemet så varierar resultaten. Den största minskningen av växthusgaser uppstår när ett renoveringspaket utförs på en byggnad i ett fjärrvärmesystem med hög andel biobränsle och ingen elproduktion.

In this thesis, two electric vehicles are compared, a fuel cellpowered vehicle and a battery powered vehicle with a conventionalvehicle with an internal combustion engine. The comparison wasdone as a life cycle assessment and consisted of two stages, avehicle stage and a fuel stage. The vehicle stage consisted ofeverything from mining minerals to recycling of the vehicles,every aspect that’s connected to the car. The fuel stage consistedof fuel production and use during the vehicle’s lifetime. The fuelconsist of electricity and hydrogen produced through electrolysis. The goal of the thesis was to understand what aspects of thelifecycle matters most in terms greenhouse gases for each of theelectric vehicles. Since there are no emissions in terms ofgreenhouse gases while driving the electric vehicles, only fuelproduction, electricity and hydrogen through electrolysis, countedtowards the fuel stage. For the vehicle with an internalcombustion engine the fuel stage consisted of gasoline productionand emissions from driving. The results showed that when comparing electric vehicles withinternal combustion vehicles, the most important aspect was theelectricity mix, with a Nordic electricity mix for most use casesthe electric vehicles where more climate friendly then theinternal combustion vehicles. The fuel cell powered vehicle usedmore electricity than the battery powered vehicle when usingelectrolysis to create hydrogen, and therefore was more sensitiveto increases in emissions from the electricity mix. When comparingthe vehicle stage, battery production causes the most emissionsfor the battery powered vehicle and the hydrogen tank caused themost emissions for the fuel cell powered vehicle.

Improving energy performance of existing buildings is an important part in decreasing energy use and in turn reduce the greenhouse gas emissions caused by human activity and the primary energy use. To be able to evaluate how energy refurbishment influences the greenhouse gas emissions and the primary energy use a wider system perspective is needed that puts the building in its context. This thesis deals with energy refurbishment packages performed on multi-family buildings within district heated areas and how they influence greenhouse gas emissions and primary energy use when the district heating use is altered. A simulated building is used to evaluate several energy refurbishment packages. The results are used as input data for models of district heating systems to cost optimize the district heating production. The results from the cost optimization are used to evaluate the impact on greenhouse gas emissions and primary energy use. The results show a difference between measures that saves district heating without increasing the use of electricity and measures that increases the use of electricity while district heating is saved. For example, a building refurbishment package including only building envelope improvements saves the same amount of district heating as a package including only mechanical ventilation with heat recovery. Despite this, the emissions of greenhouse gases and the use of primary energy is to a greater extent reduced in the first package because the use of electricity remains unchanged. Comparing energy refurbishment packages performed on the same building, but within different district heating systems, show the importance of the design of the district heating system. Depending on the fuel types used and to which extent electricity is co-produced in the district heating system, the results of implementing the energy refurbishment packages vary. The largest reduction of greenhouse gases and primary energy use occurs when a refurbishment package is performed on a building in a district heating system with high share of biofuel and no electricity production. / Att förbättra energiprestanda hos befintliga byggnader är en viktig del i arbetet med att minska energianvändningen och i sin tur minska utsläpp av växthusgaser orsakade av mänsklig aktivitet samt att minska användningen av primärenergi. För att kunna utvärdera hur energieffektivisering av byggnader påverkar växthusgasutsläpp och primärenergianvändning behövs ett brett systemperspektiv som sätter byggnaden i sitt sammanhang. Denna avhandling handlar om hur paket av energieffektiviseringsåtgärder som utförs på flerfamiljshus inom fjärrvärmeuppvärmda områden påverkar växthusgasutsläpp och primärenergianvändning när fjärrvärmeanvändningen förändras. Resultaten visar på skillnader mellan åtgärder som sparar fjärrvärme utan att öka användningen av el och åtgärder som ökar användningen av el medan fjärrvärme sparas. Till exempel sparar ett energieffektiviseringspaket som endast omfattar byggnadsskalsförbättringar samma mängd fjärrvärme som ett paket som endast omfattar installation av mekanisk ventilation med värmeåtervinning. Trots detta minskar utsläppen av växthusgaser och användningen av primärenergi i större utsträckning i det första paketet på grund av att elanvändningen förblir oförändrad. Vikten av fjärrvärmesystemets utformning visas då en byggnad där olika energieffektiviseringspaket testats, flyttas runt till olika fjärrvärmesystem. Beroende på vilka bränsletyper som används och i vilken utsträckning som el produceras i fjärrvärmesystemet så varierar resultaten. Den största minskningen av växthusgaser uppstår när ett renoveringspaket utförs på en byggnad i ett fjärrvärmesystem med hög andel biobränsle och ingen elproduktion.

With the transport sector switching to electric energy to reduce greenhouse gas emission, the supply and demand in the energy system are impacted by this transition. Meanwhile, there are not a lot of studies focus on the electrification of the vehicle fleet in Sweden. To fill up the knowledge gap, the paper aims to identify the total required electrical energy and power for the electrification of the vehicle fleet in Sweden. This includes switching passenger vehicles, light and heavy trucks, and buses to battery electric vehicles. An Electric Vehicle Power Demand Model is designed to answer the research question. It is a simplified model that can calculate energy consumption and power demand from an electric vehicle fleet. To simulate the charging schedule, four scenarios are created with differences in charge speed and the use of smart or unregulated charging. Based on the model, the electric vehicle fleet consumes 20.4 TWh of electricity per year, accounting for 14.7% of total demand in Sweden. Combing the vehicle fleet with other energy services, an average hourly peak load of 16.2 GW in summer and 24.3 in winter can be seen, while the available capacity in Sweden is around 27.1. The result indicates that the current Swedish energy system is capable of handling demand from charging the electric vehicle fleet in terms of power capacity for most times. However, undersupply may happen in some extreme condition during the winter due to higher consumption from other energy services. Furthermore, with the increasing share of renewable power in the system, the availability of these power plants can have a direct impact on the supply. This requires smart charging to shift the charging events to prevent peak hours, which can potentially decrease the peak loads up to 2 GW in EV charging demand during peak hours. However, the actual effect of it still requires more study. Lastly, the model created for the research can be used as a research or decision-making tool to estimate the impact of a group of electric vehicles in the future, therefore, contribute to the development of the sustainable energy transition.