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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Life Cycle Impacts of Road Infrastructure : Assessment of energy use and greenhouse gas emissions

Miliutenko, Sofiia January 2012 (has links)
Road infrastructure is essential in the development of human society, but has both negative and positive impacts. Large amounts of money and natural resources are spent each year on its construction, operation and maintenance. Obviously, there is potentially significantenvironmental impact associated with these activities. Thus the need for integration of life cycle environmental impacts of road infrastructure into transport planning is currently being widely recognised on international and national level. However certain issues, such as energy use and greenhouse gas (GHG) emissions from the construction, maintenance and operation of road infrastructure, are rarely considered during the current transport planning process in Sweden and most other countries.This thesis examined energy use and GHG emissions for the whole life cycle (construction, operation, maintenance and end-of-life) of road infrastructure, with the aim of improving transport planning on both strategic and project level. Life Cycle Assessment (LCA) was applied to two selected case studies: LCA of a road tunnel and LCA of three methods for asphalt recycling and reuse: hot in-plant, hot in-place and reuse as unbound material. The impact categories selected for analysis were Cumulative Energy Demand (CED) and Global Warming Potential (GWP). Other methods used in the research included interviews and a literature review.The results of the first case study indicated that the operational phase of the tunnel contributed the highest share of CED and GWP throughout the tunnel’s life cycle. Construction of concrete tunnels had much higher CED and GWP per lane-metre than construction of rocktunnels. The results of the second case study showed that hot in-place recycling of asphalt gave slightly more net savings of GWP and CED than hot in-plant recycling. Asphalt reuse was less environmentally beneficial than either of these alternatives, resulting in no net savings of GWP and minor net savings of CED. Main sources of data uncertainty identified in the two case-studies included prediction of future electricity mix and inventory data for asphalt concrete.This thesis contributes to methodological development which will be useful to future infrastructure LCAs in terms of inventory data collection. It presents estimated amounts of energy use and GHG emissions associated with road infrastructure, on the example of roadtunnel and asphalt recycling. Operation of road infrastructure and production of construction materials are identified as the main priorities for decreasing GHG emissions and energy use during the life cycle of road infrastructure. It was concluded that the potential exists for significant decreases in GHG emissions and energy use associated with the road transport system if the entire life cycle of road infrastructure is taken into consideration from the very start of the policy-making process. / QC 20120229
2

Global warming potential reduction by carbon dioxide utilization in the production of synthesis gas and its derivatives

Medrano, Juan Diego 16 September 2019 (has links)
The indiscriminate emission of CO2 is drastically aggravating climate change. Carbon Capture and Utilization (CCU) was born as a complementary solution to this issue. This thesis studies the consumption of carbon dioxide in industrial processes, starting from synthesis gas, and using this building block in subsequent syntheses; ultimately integrating CO2 utilization with previously non-CO2 consuming processes.
3

Status Mapping of tank to grave management of Low-GWP refrigerants.

Parra Gimeno, Sandra January 2023 (has links)
Refrigeration plays a vital role today in various residential, commercial, and industrial processes, requiring refrigerants to facilitate the cooling or heating processes. Over time, refrigerants have undergone significant changes to meet technological, social, environmental, and economic needs. Refrigerants' evolution can be categorized into four generations. The first three generations come from the early use of natural compounds (CO2, SO2), to the dominance of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), followed by the ozone protection era of hydrofluorocarbons (HFCs)1. However, HFCs presented new challenges due to their high Global Warming Potential (GWP), leading to the development of 4th generation refrigerants formed by hydrofluoroolefins (HFOs) like R- 1234yf. However, to minimize GHG emissions even more and phase out of high Global Warming Potential (GWP) alternatives, following the Montreal Protocol (globally) and the F-Gas Regulation (Europe), low-GWP refrigerants emerge. This group includes compounds with a GWP value below or equal to 150, such as natural refrigerants, new synthetic (R-1234yf) or older compounds (R-152a). The research gap in this MSc thesis addresses the management of particularly synthetic low-GWP refrigerants throughout their entire useful lifecycle, focusing on the tank-to-grave concept. This concept addresses the useful life of the refrigerants, starting with their procurement and charging into refrigeration and heat pump units (during manufacturing), and then their distribution, use, and end-of-life management. This, therefore, excludes the extraction of raw materials and manufacturing of refrigerants. However, the Life Cycle Assessment (LCA) approach analyses environmental impacts in all product phases (including raw materials extraction). Within this context, this thesis explores the different stakeholder procedures and activities for managing refrigerants throughout their lifetime. Different stakeholders or organizations, including heat pump/refrigeration system manufacturers, their service organizations, end-users, and end- of-life management organizations are involved in this process. Whenever possible, a representative or more from a given stakeholder category was thus interviewed. However, possible limitations such as lack of certain stakeholder involvement, limited information about some stakeholder groups, as well as the assumption of generalisability of the results obtained, are considered throughout this report. For stakeholder categories for which interviewing was not possible, literature-based mapping was conducted. Furthermore, comprehending the current legislation and standards was done as it is essential to grasp the complete process of handling of refrigerants. Additionally, as it concerns the management of refrigerants throughout their useful lifecycle, studying their potential applicability with Life Cycle Assessment (LCA) is of interest. Finally, the entire project is analysed from a sustainability perspective, exploring the advantages and disadvantages it entails. Before delving into the information about stakeholders, it is essential to establish a theoretical context related to the process of refrigerant management. The first key role is to understand Life Cycle Thinking (LCT), LCA and Material Flow Analysis (MFA) and how to apply these to the management of refrigerants. In addition, the concept of tank-to-grave management is explained, along with the various groups or organizations involved in different phases of a refrigerant's life. These groups include manufacturers, service organizations, supplier organizations, cold chain organizations, recovery organizations, reclamation organizations, disposal organizations as well as certain related associations and certifying bodies. Furthermore, given the importance of the concept of recovery in this project, its meaning is compared from the perspective of refrigerant management and waste hierarchy. Furthermore, the F-Gas Regulation and some of its articles, related to leakage control and the frequency of leakage checks according to the type of equipment used, how the recovery process should be carried out or the strategies related to market positioning and control of the use of these F-gases are studied. In addition, the Air-Conditioning, Heating and Refrigeration Institute (AHRI) standards are investigated, as they are widely used in the refrigeration sector and explain some procedures related to activities such as composition analysis or procedures to be performed with recovery equipment. Lastly, the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation and the potential implications of implementing the per-and poly-fluoroalkyl substances (PFAS) ban proposal are explored due to their significant possible impact on the refrigeration industry in future years. This is because PFAS includes almost all synthetic refrigerants. To gather information about the current situation and practices in the refrigeration sector, the research adopts a qualitative approach, centred on in-depth interviews with different stakeholders. These interviews provide valuable firsthand insights into the practices, experiences, and perceptions of stakeholders regarding the management of synthetic low-GWP refrigerants. These interviews were based on a series of questionnaires, developed, and customized within the project, according to the types of organization. Moreover, with the interviewees' consent, these interviews were recorded, and transcriptions were created. These transcripts were systematically coded and analysed to identify recurring themes and patterns, as well as differences between the different stakeholders’ inputs. The next point to address was the concept of sustainability. The goal is to introduce this concept and explain its significance in society, particularly with the implementation of initiatives like the United Nations Sustainable Development Goals (SDGs). Therein, these concepts were applied to the topic and scope of this master’s thesis, i.e., on refrigerants management, discussing some advantages, and disadvantages regarding the use of refrigerants and some steps of their management. The thesis shows that the current refrigeration industry is not only dominated by synthetic low-GWP refrigerants, but also natural refrigerants are widely used. Additionally, different opinions and methodologies arose regarding a series of topics. Firstly, when discussing whether they checked for changes in refrigerant composition, it was not possible to obtain a general trend. Secondly, for leak detection systems, different methodologies were used depending on the needs of the organisation, but both manual and fixed systems were mentioned. Finally, regarding end-of-life management, all organizations agreed that the first step should be the recovery of the refrigerant. After that, there are two different options: reclamation (purifying an old refrigerant to obtain one with the characteristics of a virgin refrigerant), and disposal (usually by sending the refrigerants to incineration). F-Gas Regulation and AHRI are the most widely used regulations at present, while organizations expect the PFAS ban to become a real regulation in the future. As a result, most organizations are leaning towards a future dominated by natural refrigerants, which may necessitate new regulations, certain technical changes, and possibly new business models. To conclude, tank-to-grave management of synthetic low-GWP refrigerants offers opportunities for the refrigeration industry, as this concept helps to let you know all the stakeholders involved and the processes they employ, and together with the application of the LCT approach, it is easier to understand how different activities, e.g., recovery and reclamation, can be improved to reduce the environmental impact of these compounds. The study finally considered both natural and synthetic low-GWP refrigerants. Moreover, technical aspects such as analysis composition or leak detection systems, together with end-of-life management approaches and techniques (reclamation or disposal) differed between organizations, so no global trend regarding the Swedish situation could be given. Finally, two possible scenarios arise regarding the legislation: on the one hand, if the PFAS ban proposal is not approved, the industry would continue phasing out high-GWP refrigerants while prioritising reclamation and/or waste energy use from incineration of synthetic low-GWP refrigerants. On the other hand, if the ban is approved, natural refrigerants would become the main and almost only option, requiring adjustments and compliance with new regulations due to their flammability. About the future work to do in this thesis, new interviews with stakeholders that were not interviewed the first time. Moreover, a second round of interviews to address doubts that have appeared. Finally, to study how the rate of reclaimed refrigerants can be increased. / Kylteknik spelar en avgörande roll idag i olika bostads-, kommersiella och industriella processer, och kräver köldmedier för att underlätta kyl- eller värmepumpsteknik processarna. Över tiden har köldmedium genomgått betydande förändringar för att möta teknologiska, sociala, miljömässiga och ekonomiska behov. Köldmediernas utveckling kan kategoriseras i fyra generationer. De första tre generationerna kommer från den föregående användningen av naturliga komponenter (CO2, SO2), till dominansen av klorfluorkarboner (CFCs) och hydroklorfluorkarboner (HCFCs), följt av ozonskyddsperioden med hydrofluorkarboner (HFCs). Dock presenterade HFCs nya utmaningar på grund av deras höga Globala Uppvärmningspotential (GWP), vilket ledde till utvecklingen av fjärde generationens köldmedier, som bildas av hydrofluorolefiner (HFOs) som R-1234yf. För att dock minska växthusgasutsläppen ännu mer och fasa ut hög-GWP-alternativ enligt Montrealkonventionen (globalt) och F-gasförordningen (Europa), utvecklades låg-GWP-köldmedier. Denna grupp inkluderar komponenter med ett GWP-värde som är lägre än eller lika med 150, såsom naturliga köldmedier, nya syntetiska (R-1234yf) eller äldre komponenter (R-152a). Forskningsgapet i denna exjobb behandlar hanteringen av särskilt låg-GWP- köldmedier under hela deras användbara livscykel och fokuserar på tank-till-grav-konceptet. Detta koncept tar upp köldmediernas användbara livslängd, börjande med deras upphandling och påfyllning i kylteknik- och värmepumpsenheter (under tillverkning), och sedan deras distribution, användning och hantering vid livets slutskede. Detta exkluderar därför utvinning av råmaterial och tillverkning av köldmedier. Medan Livscykelbedömningsmetoden (LCA) analyserar miljöpåverkan i alla produktfaser. Inom denna kontext syftar denna avhandling till att utforska de olika intressenternas procedurer och aktiviteter för att hantera köldmedium under deras livstid. Olika intressenter eller organisationer, inklusive tillverkare av värmepumpar/kylsystem, deras serviceorganisationer, slutanvändare och organisationer för hantering av livets slutskede, är involverade i denna process. När det var möjligt, intervjuades en representant eller flera från en given intressentkategori. Eventuella begränsningar såsom brist på viss intressentmedverkan, begränsad information om vissa intressentgrupper, samt antagandet om generaliserbarhet av de erhållna resultaten, beaktas genom hela denna rapport. För intressentkategorier där intervjuer inte var möjliga, genomfördes kartläggning baserad på litteratur. Vidare genomfördes en förståelse av nuvarande lagstiftning och standarder, eftersom det är väsentligt att förstå hela processen för hantering av köldmedium. Dessutom, då det gäller hanteringen av köldmedier under deras användbara livscykel, är det intressant att studera deras potentiella användbarhet med Livscykelbedömningen (LCA). Slutligen analyseras hela projektet ur ett hållbarhetsperspektiv, där fördelar och nackdelar utforskas. Innan vi dyker in i informationen om intressenter är det väsentligt att etablera en teoretisk kontext relaterad till processen för hantering av köldmedium. Den första nyckelrollen är att förstå Livscykeltänkande (LCT), LCA och Materialflödesanalys (MFA) och hur dessa kan tillämpas på hanteringen av köldmedier. Dessutom förklaras konceptet med tank-till-grav-hantering, tillsammans med de olika grupperna eller organisationerna som är involverade i olika faser av ett köldmedium liv. Dessa grupper inkluderar tillverkare, serviceorganisationer, leverantörsorganisationer, kyltekniskedjeorganisationer, återvinnings- och reklamationsorganisationer, avfallshanteringsorganisationer (som handlar kassering) samt vissa relaterade komponenter och certifierande organ. Vidare, med tanke på vikten av återvinningskonceptet i detta projekt, jämförs dess betydelse ur perspektivet av köldmediumshantering och avfallshanteringshierarkin. Vidare studeras F-gasförordningen och några av dess artiklar, relaterade till läckagekontroll och frekvensen för läckagekontroller enligt typen av utrustning som används, hur återvinningsprocessen bör genomföras eller strategier relaterade till marknadspositionering och kontroll av användningen av dessa F-gaser. Dessutom undersöks standarderna från Air-Conditioning, Heating and Refrigeration Institute (AHRI), eftersom de används brett inom kylteknisksektorn och förklarar vissa procedurer relaterade till aktiviteter såsom sammansättningsanalys eller procedurer som ska utföras med återvinningsutrustning. Slutligen utforskas REACH-förordningen (Registration, Evaluation, Authorisation and Restriction of Chemicals) och de potentiella konsekvenserna av att genomföra förslaget om förbud mot per- och polyfluoralkylämnen (PFAS), på grund av deras betydande möjliga påverkan på kyltekniskaindustrin under kommande år. Detta beror på att PFAS inkluderar komponenter som ingår i gruppen med låg-GWP- köldmedier. För att samla information om den nuvarande situationen och praxis inom kylteknisksektorn använder forskningen en kvalitativ metodik, fokuserad på djupgående intervjuer med olika intressenter. Dessa intervjuer ger värdefulla förstahandsinsikter i intressenternas praxis, erfarenheter och uppfattningar om hanteringen av låg-GWP- köldmedier. Dessa intervjuer baserades på en serie enkäter som utvecklades och anpassades inom projektet, enligt organisationstyper. Dessutom spelades dessa intervjuer in med intervjuobjektens samtycke, och transkriptioner skapades. Dessa avskrifter kodades och analyserades systematiskt för att identifiera återkommande teman och mönster samt skillnader mellan olika intressenters synpunkter. Det nästa punkten att behandla var begreppet hållbarhet. Målet är att introducera detta begrepp och förklara dess betydelse i samhället, särskilt med införandet av initiativ som FNs hållbarhetsmål (SDGs). Därigenom tillämpades dessa begrepp på ämnet och omfattningen av denna exjobb, det vill säga hantering av köldmedier, och diskuterades vissa fördelar och nackdelar med användningen av köldmedium samt vissa steg i deras hantering. Uppsatsen visar att den nuvarande kyltekniskaindustrin inte bara domineras av låg-GWP-köldmedier, utan naturliga köldmedier används också i stor utsträckning. Dessutom framkom olika åsikter och metoder om en rad ämnen. För det första, när det diskuterades om de kontrollerade förändringar i köldmedier sammansättning, var det inte möjligt att få fram en allmän trend. För det andra, när det gäller läckagedetekteringssystem, användes olika metoder beroende på organisationens behov, men både manuella och fasta system nämndes. Slutligen, gällande hantering av livets slutskede, var alla organisationer överens om att första steget borde vara att återvinna köldmedier. Därefter finns det två olika alternativ: återvinning (rensa ett använt köldmedium för att erhålla ett med egenskaperna hos ett jungfruligt köldmedium) och kassering (vanligtvis genom att skicka köldmedier till förbränning). F-Gasförordningen och AHRI är de mest använda reglerna för närvarande, medan organisationer förväntar sig att förbudet mot PFAS kommer att bli en verklig reglering i framtiden. Som ett resultat lutar de flesta organisationer mot en framtid dominerad av naturliga köldmedier, vilket kan kräva nya regler, vissa tekniska förändringar och möjligen nya affärsmodeller. Sammanfattningsvis erbjuder tank-till-grav-hantering av låg-GWP-köldmedier möjligheter för kyltekniskaindustrin, då detta koncept hjälper till att identifiera alla involverade intressenter och de processer de använder sig av. Tillsammans med tillämpningen av LCT blir det lättare att förstå hur olika aktiviteter, t.ex. återvinning och rening, kan förbättras för att minska miljöpåverkan från dessa materialer. Studien beaktade både naturliga och låg-GWP- köldmedier. Dessutom skilde sig tekniska aspekter såsom sammansättningsanalys eller läckagedetekteringssystem, tillsammans med slutskedeshanteringsmetoder och tekniker (återvinning eller kassering) mellan organisationer, så ingen global trend angående den svenska situationen kunde fastställas. Slutligen framträder två möjliga scenarier avseende lagstiftningen: å ena sidan, om förslaget om förbud mot PFAS inte godkänns, skulle industrin fortsätta fasa ut hög-GWP- köldmedier och samtidigt prioritera rening och/eller energiåtervinning från förbränning av låg-GWP- köldmedier. Å andra sidan, om förbudet godkänns, skulle naturliga köldmedier bli huvudalternativet och nästan det enda alternativet, vilket kräver anpassningar och efterlevnad av nya regler på grund av deras brandfarlighet. Om framtida arbete i denna avhandling, inkluderar det nya intervjuer med intressenter som inte intervjuades första gången. Dessutom en andra omgång intervjuer för att ta upp de tvivel som har uppstått. Slutligen, att studera hur återvunna köldmedium kan öka i takt.
4

Economic and environmental optimization of deep energy renovation strategies for an office building in Sweden

Sauterleute, Eva January 2022 (has links)
Energy efficiency of the building sector is a key strategy to achieve national climate goals in Sweden and other European countries. In this thesis, several renovation scenarios for a case study office building in Sweden are analysed and compared based on their energy performance, environmental impacts, and economic costs from a life cycle perspective. As a baseline, the case study building was simulated in IDA ICE and compared with the simulated renovation scenarios. For the Life Cycle Analysis (LCA) and the Life Cycle Costs (LCC), the commercially available software OneClickLCA was used. The renovation scenarios were carried out over three rounds: (i) material type scenarios where five insulation materials (glass wool, rock wool, hemp fiber, Expanded Polystyrene (EPS), and Extruded Polystyrene (XPS)) and two frame materials (wood and steel) are compared; (ii) insulation thickness optimization from economic and environmental performance perspectives (iii) comparison of combination with other typical renovation measures such as changing of windows, improving specific fan power, heat exchanger efficiencies, and lightings. The results show that glass wool gives the most economical and environmental performance, followed by rock wool and EPS. When considering other environmental indicators, hemp fiber presents the best environmental option. However, it is not competitive with traditional insulation materials from an economic perspective. The insulation thickness scenarios show different optimal economic and environmental performance points, giving total energy savings of 5 % and 9,5 %, respectively. When considering other typical energy efficiency measures, the highest impact on the energy performance was found when improving the specific fan power (SFP) and switching to LED lights with total electricity reductions (including user-based electricity consumption) of 4 % and 14 %, respectively. Conclusively, the case study showed how the electricity and heating demand of the studied office building could be reduced, and the environmental and economic consequences of the different energy-efficiency measures.

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