The paper at hand presents the environmental impact analysis of a photovoltaic (PV) power station sited in Stockholm, Sweden, using life cycle assessment (LCA). The LCA considers the primary energy return on investment and global warming potential of the PV-station, including; resource extraction, manufacturing, transportation, operation and maintenance, and decommissioning. Other environmental impact indicators are also presented, such as; the eutrophication, acidification, human toxicity, and ozone depletion potentials. The results show that the most critical phase of the lifecycle is the upgrade from metallurgical to solar grade silicon due to the high consumption of energy. The emissions results are compared to the emissions factors used for calculations in Sweden in accordance with the Swedish Energy agency and the European Commission’s directive for emissions calculations. The results for the other environmental indicators showed inconsistencies compared to existing studies, something that is according to the IEA’s guideline for PV-systems LCA caused by data scarcity and the indicators lacking consensus within the PV LCA-community. The studied PV-station is expected to reach energy neutrality after 2,4 years and offset annual GHG emissions of up to18 ton of CO 2 equivalents. / Studien tillhands presenterar miljöutvärderingen av en fotovoltaisk solcellsanläggning i Stockholm. Detta utfördes med hjälp av livscykelanalysverktyget. Analysen använder energiåterbetalningstiden och den globala uppvärmningspotentialen som indikatorer på anläggningens miljöinverkan. Både återbetalningstiden och den globala uppvärmningspotentialen beräknas för gruvarbetet, transporten, drift och underhåll samt avveckling och bortskaffning av anläggningen. Överföringsförluster beräknas också över anläggningens livscykel. Andra indikatorer som beräknas i denna studie är potentialen för försurning, övergödning, ozonnedbrytning och humantoxicitet. Dessa beräknas endast för modulens tillverkningskedja. Studiens resultat visar att den mest kritiska processen under solcellsanläggningens livscykel är kiselmetallens omvandling till solkisel, detta med avseende på energiförbrukningen och utsläpp av växthusgaser. Anläggningens globala uppvärmningspotential uttrycks i växthusgasutsläpp och jämförs med den nordiska elmixens utsläppsfaktor. Jämförelsen görs enligt dem gällande EU-direktiven. Resultaten för dem andraindikatorerna har visat på väsentliga avvikelser jämfört med tidigare studier. Detta beror enligt det internationella energirådet på databrist och på att dessa indikatorer saknar stöd inomLCA samfundet. Solcellsanläggningen beräknas bli energineutral efter 2,4 år samt eutralisera utsläpp på upp till 18 ton koldioxidekvivalenta per år.

The European Commission has proposed a “renovation wave” to increase energy efficiency in buildings. Retrofitting can decrease operational energy usage but requires material production. Using the concepts of energy payback time and carbon payback time, this thesis aims to analyse under what circumstances operational energy savings from window replacement compensate for the climate impact of producing new windows. The literature review shows that carbon payback times for energy retrofitting measures are often reported to be merely a few years. In some cases, however, carbon payback time exceeds the service life of the added material. In general, diverging results can be attributed to both case specific circumstances and methodological choices. In this thesis, values for the main parameters determining carbon and energy payback time for window replacement are retrieved from environmental product declarations and scientific literature. The analysis shows that, only accounting for operational energy, energy payback times are within the expected service life of the researched windows for all energy saving scenarios and well within the service life for the midrange scenarios. Taking account of primary energy stretches the span of results. The analysis also shows that carbon payback time for window replacement varies by a factor of 38 for the midrange studied scenarios and a factor of almost 4 600 for the most extreme among the studied scenarios. Divergence stems from all investigated parameters: the embodied climate impact of window production, the amount of saved operational energy and the emission factor attributed to saved energy. In countries with mainly renewable operational energy, case studies may arrive at long carbon payback times for window replacement. The result can be altered if saved energy is considered to come from marginal production techniques, a methodological choice made in some case studies.   This thesis concludes that if energy and carbon payback time calculations are to be used for comparing retrofit alternatives, the research community needs to address methodological issues. Another conclusion is that the analysis of climate performance needs to include the interconnectedness of different societal sectors. It also needs to include more impact categories than energy and greenhouse gases, for example resource depletion.

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To be able to mitigate the climate change and disasters that will come with it and to ensure economic growth, there is a need for change. A good start is more renewable energy and less harmful emissions. It is known that solar energy is sustainable and made from an endless source, the sun. However, it is not known how much impact the photovoltaic solar panels have through its entire lifecycle, from extraction of raw materials to End of Life management. This study has investigated photovoltaic solar panels' full life cycle to see how sustainable they really are. Including where the biggest opportunities for improvement of environmental, financial and social sustainability within the value chain is found. The results have been obtained by conducting a literature study, interviews with people with expertise of different parts of the value chain and finally calculations have been made to compare and visualize the findings. Two main ways to improve the PV panels’ negative impact in terms of environmental, financial and social sustainability have been established. Firstly, the study suggests the importance of implementing advanced recycling within the value chain. Recycling a high percentage of materials in the PV panel, and reusing the recovered material in production will decrease the energy consumption and harmful emissions significantly, alongside increasing circularity of critical materials and bring both financial and social benefits. Secondly, moving the better part of the production to Europe from China would also decrease the negative impact of the PV panels, especially the environmental and social impact, the study could however not find sufficiently good arguments for financial improvement to move the production to Europe. To be conclusive, this subject would need further studies. / För att kunna lindra klimatförändringar och de medföljande katastroferna och säkerställa den ekonomiska tillväxten finns det ett stort behov av förändring. En bra start är att använda mer förnybar energi och som bidrar till färre skadliga utsläpp. Det är känt att solenergi är hållbart med bränsle från en oändlig källa, solen. Det är emellertid inte känt hur stor påverkan solcellspanelerna har under hela dess livscykel, från utvinning av råvaror till dess panelens liv är över. Denna studie har undersökt solcellspanelernas hela livscykel för att se hur hållbara de egentligen är. Studien har även studerat var de största möjligheterna för förbättring av miljömässig, finansiell och social hållbarhet inom värdekedjan finns. Resultaten har erhållits genom att genomföra en litteraturstudie, intervjuer av personer med expertis inom olika delar av värdekedjan och slutligen har beräkningar gjorts för att jämföra och visualisera resultaten. Två huvudsakliga sätt att förbättra solpanelernas negativa påverkan när det gäller miljömässig, ekonomisk och social hållbarhet har identifierats. För det första föreslår studien vikten av att implementera avancerad återvinning inom värdekedjan. Återvinning av en hög andel material i solcellspanelen och återanvändning av det återvunna materialet i produktionen kommer att minska energiförbrukningen och skadliga utsläpp avsevärt samt förbättra cirkuläriteten av kritiska material och medföra både ekonomiska och sociala fördelar. För det andra skulle förflyttning av den större delen av produktionen till Europa från Kina också minska de negativa effekterna av solcellspaneler, särskilt de miljömässiga och sociala effekterna, studien kunde dock inte hitta tillräckligt med goda argument för att en förflyttning av produktionen till Europa skulle leda till en ekonomisk förbättring. För att detta ska vara avgörande skulle detta ämne behöva ytterligare studier.

根據歐盟2009 年發布之再生能源指令，定義熱泵系統所擷取之大氣熱能、水熱能以及地熱能為再生能源之選項，熱泵技術不受日夜與天候影響，且具安全、有低耗能、低排碳的優點，可應用在空調、暖氣、熱水等設備，備受歐美日本等先進國家重視，也是歐美各國政府極力推廣的項目之一。本研究針對台灣地區家戶住宅所使用小型空氣源熱泵熱水機組，透過環境資源及能源效率的角度，來探討熱泵熱水系統對於台灣住宅部門的適用性。 在研究方法上，針對國內熱泵個案廠商進行系統盤查分析，並且估算使用運轉過程中所需之能源投入，以計算熱水系統在製造過程與運轉使用過程中之環境影響。選擇生命週期評估軟體SimaPro 7.3做為評估工具，使用Eco-Indicator 95、EPS 2000兩種衝擊評估模式，來以生命週期評估探討熱泵熱水系統對環境之影響。並輔以淨能源分析法中能源投資報酬率與能源回收期，以及估算熱泵熱水系統生命週期CO2排放量，來衡量熱泵熱水系統之能源效率是否具有其效益。並進一步針對不同的再生能源發電比例與提升熱泵能源效率比例，探討不同方案的敏感度分析。 根據本研究分析結果顯示，熱泵熱水系統不管從Eco-indicator 95或EPS 2000衝擊評估模式下，運轉使用階段對環境衝擊較大，主要的衝擊項目為重金屬汙染，是因為熱泵熱水系統運轉所使用的電力消耗所致。使用熱泵熱水系統對環境衝擊程度遠較電熱水系統來得小，雖在Eco-indicator 95之衝擊評估模式下，瓦斯熱水系統較熱泵熱水系統環境衝擊程度較小，但以EPS 2000衝擊評估模式下，熱泵熱水系統對環境是最為友善的熱水系統。以淨效益估算熱泵熱水系統源投資報酬（EROI）值為1.45～5.55，能源回收期約為0.22年至2.16年，表示熱泵熱水系統從生命週期的角度來檢視能源效率是具有效益的。由於目前熱泵熱水系統對環境最大的負擔來源是電力的使用，若未來能提高再生能源發電比例、降低臺灣電能含碳濃度，或者提高熱泵能源生產效率，均能降低熱泵熱水系統對環境的負面影響。 / The purpose of this study is to apply life cycle assessment (LCA) and net energy analysis to explore the environmental impacts of the heat pump water heater in Taiwan. In order to achieve this objective, domestic data inventory was gathered from local heat pump industry in Taiwan through questionnaires including input of energy, product output and waste, etc. The SimaPro7.3 program and two impact assessment methods including Eco-Indicator 95, EPS 2000 were utilized to evaluate the environmental impact of the heat pump water heater. Also, we used net energy analysis such as energy return on investment and energy payback time, and estimated the life-cycle CO2 emissions to see whether if the heat pump water heater has its energy efficiency. In addition, the sensitivity analysis was performed by varying renewable energy generation portfolio and the heat pump energy efficiency ratio. Emprical results of two impact assessment methods (Eco-indicator 95 and EPS 2000) show that the main impact on environment of heat pump water heater is from operation phase. When operating the heat pump water heater, it needs to consume electricity which is generated from fossil fuel and caused the environmental impact. Compared with the electric water heater, the environmental impact degree of heat pump water heater is much smaller. In Eco-indicator 95 method, gas water heater has less influence on the environment than heat pump water heater; however, heat pump water heater is the most environment-friendly system in EPS 2000 method. That is because gas is a kind of nonrenewable resource. From the viewpoint of resource stock, gas indeed influence “Depletion of reserves” of environmental impact. By utilizing net energy analysis, the estimated energy return on investment (EROI) of heat pump water heater is 1.45～5.55, and energy payback time is 0.22~2.16 years. It indicates that heat pump water heater has significant benefit from life-cycle perspective. The main impact to environment by heat pump water heater is essentially derived from electricity input. To mitigation this environmental issue, one can reduce environmental impact by increase the proportion of renewable energy generation, and reducing the electricity CO2 emission. Furthermore, improving the energy efficiency of the heat pump would also helpful.