According to the Intergovernmental Panel on Climate Change, Carbon Dioxide Removal (CDR) technologies play a significant role in deep mitigation pathways to limit global temperature rise to 1.5°C. As a result, interest in them is becoming increasingly prevalent, the most widely discussed being Direct Air Capture (DAC), or active removal of carbon dioxide from atmospheric air. While DAC processes have indeed been successfully tested, one of the most prominent being that developed by Canadian company Carbon Engineering, their widespread deployment faces significant headwinds due to prohibitively high energy consumption and its associated costs. Before DAC can be considered to exist in a state of technological readiness, reductions to the installations' energy demand must be realized. This thesis analyzes the thermodynamic behavior of Carbon Engineering's proposed 1 Mt-CO2/year natural gas fuelled DAC plant, which they describe as “a low-risk starting point rather than a fully optimized least-cost design” [Keith et al., Joule 2, 1573], with the aim to illustrate key areas to which energy efficiency improvement measures must target. With an understanding built of the mechanisms by which energy is utilized and irreversibly lost within their plant, suggestions are put forth for directions to pursue for process improvements, with further analysis included on potential alternative plant configurations which would reduce overall heat and power consumption. A thermodynamic work loss analysis is performed on their plant design at a system level, which finds 92.2% of incoming exergy being lost to thermodynamic irreversibilities. A component-level analysis is then performed to detail the mechanisms by which these losses occur in the most energy-intensive plant segments, namely, the calciner and preheat cyclones, air separation unit, water knockout system, CO2 compression system, and power island. The dissipation of chemical exergy in the air contactor component, i.e., the release of stored chemical exergy as low-grade heat to the environment due to the exothermic reaction of CO2 and aqueous KOH, was determined as the largest unavoidable source of work loss. The most avoidable losses were found to be associated with use of natural gas as a feedstock for heat and power, namely, through its introduction of additional CO2 and water to be processed within the plant, and due to gas turbine power production's inherent Carnot efficiency limits. Additional analysis and discussion follows regarding possible loss reduction measures and modifications, the key concept presented being the use of renewable energy to provide plant power, combined with a calciner using electric resistance heating to meet its reduced thermal demand. Use of a readily-available high-temperature heat source for calciner heat is also considered, with thorough description included of its thermodynamic advantages. Finally, the all-electric plant concept is analyzed at a system level, and its advantages compared to the original natural gas fuelled case. / Graduate

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Biogas solutions offer many benefits for the environment and society, including organic waste treatment as well as being an enabler for energy and nutrient recovery. The products of anaerobic digestion are a biogas, which contains a share of 30 to 50% carbon dioxide (CO2) and 50 to 70% methane, and a liquid remanent, rich in nutrients. The biogas can be upgraded by removing the CO2 to increase the energy content, producing biomethane. At present, CO2 is considered a waste in biomethane production systems, and hence it is emitted into the atmosphere. Nevertheless, biogas upgrading technologies separate a pure-grade CO2 and, likewise, carbon capture processes, providing a pure CO2 flow that can be stored or utilized. Compared to storage, carbon capture and utilization (CCU) technologies deliver valuable carbon-based products required to sustain human activities. The valorization of green CO2 could aid the transition towards defossilization of the economy. Indeed, several CO2 utilization technologies could be incorporated into biomethane production systems, but there is still a limited understanding of the available alternatives and their potential impacts on biomethane systems. This thesis aims to investigate the integration of CO2 utilization technologies in biomethane production systems by revealing its potential, identifying alternatives, and assessing the impacts of the integration. Using Sweden as an example, scenarios of future biomethane production were employed to estimate the potential CO2 available for utilization. To complement the analysis, a qualitative approach made possible the identification of aspects that could affect CO2 utilization in biomethane production. Moreover, a multi-criteria analysis (MCA) framework was developed to identify relevant indicators for assessment and available alternatives for CO2 utilization. The research also includes a life cycle assessment (LCA) to evaluate the climate performance of relevant CCU alternatives in the biomethane production system. Results show that 160 kt of CO2 could be obtained from biomethane production in Sweden, which could potentially increase threefold from 2020 to 2030. The evaluation of alternatives for CO2 utilization includes environmental, technical, economic, and social criteria with sound indicators within an MCA framework. Indicators to evaluate each criterion provide valuable information to identify feasible and sustainable alternatives that can be integrated into biomethane plants. The identified alternatives with a high readiness level are additional methane through methanation, horticulture, mineral carbonates, fuels, pH control, bulk chemicals, and liquefied CO2 for direct use. The results provide information to decision-makers in relation to considerations to take before implementation, like energy requirements, the existence of regulations and standards, and uncertainty. In terms of the climate performance of biomethane with the inclusion of CCU alternatives, the results show a possible reduction of CO2 emissions that depends on the possibility of substituting fossil-based products. The investigated alternatives all result in lower emissions, but concrete curing and methanation using renewable hydrogen produce the best results. To conclude, the potential future increase of green CO2 from biomethane in Sweden creates opportunities to substitute fossil carbon in current applications and mature conversion pathways. Moreover, the inclusion of CCU in biomethane production contributes to reducing biomethane system emissions and diversifying its products. Possible alternatives of CCU that can be integrated into biomethane production systems in the short term include methanation and concrete curing. Other alternatives could be possible but present lower performance and higher uncertainties at the moment. / Biogaslösningar kan ge en mängd positiva miljömässiga och samhällsviktiga effekter, inklusive behandling av organiskt avfall och framställning av energi och näringsämnen. Produkterna från anaerob rötning är dels biogas, som består från 30 till 50% av koldioxid (CO2) och 50 till 70% av metan, dels en flytande rötrest med högt näringsinnehåll. Biogasen kan uppgraderas genom att ta bort CO2 för att öka energiinnehållet, och på så vis framställs biometan. CO2 ses för närvarande som en restprodukt i produktionssystemet och släpps därför vanligtvis ut i atmosfären. Tekniker för uppgradering av biogas liknar dock processer för infångning av CO2, där högkoncentrerade flöden av CO2 lagras (CCS) eller används (CCU). Till skillnad från lagring bidrar tekniken för CCU till att skapa produkter som behövs för att upprätthålla samhällsviktiga funktioner. Dessa valoriseringar av grön CO2 skulle kunna stödja övergången mot ett fossilfritt ekonomiskt system. Faktum är att det finns ett flertal tekniker som skulle kunna integreras i produktionssystem för biometan, men kunskapen om dessa tekniker och deras inverkan på biometansystemet är begränsad. Denna avhandling syftar till att undersöka integrationen av tekniska lösningar för nyttiggörande av CO2 vid framställning av biometan genom att påvisa dess potential, identifiera alternativa tekniska lösningar, och utvärdera integrationens följder. Med Sverige som exempel skapades scenarier för framtida biometanproduktion för att uppskatta mängden CO2 som skulle kunna tas om hand. Som ett komplement till dessa uppskattningar tillämpades ett kvalitativt tillvägagångssätt som identifierade aspekter som skulle kunna påverka CO2-användningen vid biometanproduktion. Dessutom utvecklades ett multikriterieanalytiskt (MCA) ramverk för att identifiera relevanta indikatorer för utvärdering och möjliga alternativ för CO2-användning. En livscykelanalys (LCA) tillämpades även för att utvärdera klimatprestandan för relevanta CCU-alternativ inom produktionssystem för biometan. Forskningsresultaten visar att 160 kt skulle kunna erhållas från biometanproduktion i Sverige. För Sveriges del finns det en potential att öka den insamlade mängden CO2 från biometan upp till tre gånger under perioden 2020 till 2030. I utvärderingen av de tekniska lösningarna inkluderas miljömässiga, tekniska, ekonomiska och regulatoriska kriterier för indikatorer inom ett MCA-ramverk. Dessa indikatorer användes för att utvärdera hur respektive kriterium bidrar till att identifiera realiserbara tekniska lösningar som kan integreras i biometananläggningar. De identifierade teknikerna med hög mognadsgrad är framställning av ytterligare metan genom metanisering, biomassa, karbonatmineral, bränslen, pH-värdesreglering, baskemikalier och flytande CO2 för direkt användning. Varje alternativ har dock faktorer som skulle kunna hindra implementering, såsom höga energikrav, lagstiftningar och standarder samt hög osäkerhet. När det gäller klimatprestandan för biometan med olika CCU-alternativ visar resultaten på en möjlig minskning av CO2-utsläpp som beror på möjligheten att substituera fossilbaserade produkter. Alla de undersökta alternativen resulterar i lägre utsläpp, men härdning av betong och metanisering med förnybar vätgas ger bäst resultat. Slutsatsen som dras är att det finns en stor potential i Sverige att framställa grön CO2 från biometan vilken skulle skapa flera möjligheter att byta fossilbaserade produkter i nuvarande tillämpningar. Införandet av CCU i biometanproduktion kan dessutom bidra till att minska biogassystemets utsläpp och diversifiera produktutbudet. Möjliga alternativ för CCU som kan integreras med biometanproduktionssystem på kort sikt inkluderar metanisering och betonghärdning. Andra alternativ kan också vara aktuella, men uppvisar för närvarande lägre prestanda och högre osäkerhet. / <p>Funding agency: The Kamprad Family Foundation</p>

Bioenergy is extracted from biomass. What counts as biomass is generally quite diverse, but broadly speaking, it is material that previously lived. Today, energy extracted from biofuels make up around 23% of Stockholm city's total energy consumption. Stockholm city has set a goal to be a fossil-free city by 2040, i.e. zero emissions from energy use. Two sectors have been identified where emissions occur and these are the transport sector and the electricity and heating sector. This thesis will only address the electricity and heating sector. This includes all energy consumption within Stockholm city municipality. When Stockholm is developing towards a fossil fuel free city, it’s interesting to look at how important bioenergy will be as an energy source in the future. This thesis has scrutinized the role of bioenergy in reaching a fossil fuel free city. Three major policies have been investigated. The carbon dioxide tax and the emission rights system have promoted the bioenergy and its deployment in a positive way. The system of electricity certificates has shown to indirectly affect the bio energy in a negative way. The key finding is that bioenergy will have a great impact in reaching the goal mainly through its contributions with negative emissions, but it is also an important substitute to fossil fuels. / Bioenergi utvinns ur biomassa eller biobränslen. Biomassa och biobränslen är ganska diffusa begrepp då definitionen varierar runt om i världen, men generellt sett är det material som tidigare levt. Idag utgör energi från biobränslen cirka 23% av Stockholms stads totala energiförbrukning. Stockholms stad har satt upp ett mål att vara en fossilfri stad år 2040, det vill säga inga utsläpp från stadens energiförbrukning. Det finns två huvudsakliga sektorer där koldioxidutsläpp förekommer, dessa är transportsektorn och eloch värmesektorn. Detta inkluderar all energiförbrukning inom Stockholms kommuns gränser, till exempel uppvärmning av hushåll och energin de fordon som körs i staden förbrukar. När Stockholm utveckling går mot att bli en fossilbränslefri stad är det intressant att se hur viktig bioenergi kommer att vara som energikälla i framtiden. Denna rapport granskar bioenergins roll i att nå klimatmålet till 2040. De huvudsakliga slutsaterna är att bioenergi kommer ha en stor och viktig roll i att nå målet och att dess största inverkan kommer vara de negativa utsläppen. Vissa lagar har främjat bioenergin medans vissa indirekt har påverkat dess utveckling negativt. Bioenergin har en ljus framtid i Stockholm.

There is a general consensus in the literature that carbon capture and storage (CCS), a technology that controls CO2 emissions from fossil fuel power plants, figures to be a critical technology to reduce CO2 emissions to CO2 concentration stabilization levels prescribed in the literature. We completed three projects that advance the understanding of how technical change in carbon capture affects both near-future costs of CCS and the economy in the long term. First, we conducted a literature review of near-future capture cost estimates in order to get an idea of how expensive carbon capture will be in the near-future. The literature indicates that pre-combustion capture is the least expensive carbon capture technology because its combustion process best facilitates carbon capture. Second, we explored the limits of incremental technical change in each near-future capture technology using a performance-cost model. The results of the sensitivity analysis showed that pre-combustion capture could be the least expensive capture technology after incremental technical change has occurred. Third, we used an integrated assessment model (IAM) to investigate how rapid incremental and breakthrough technical change in carbon capture could impact the electric energy market, total CO2 abatement cost and CO2 price over time. We modeled breakthrough technical change using data from a paper in the literature that provides cost and performance estimates for a radical carbon capture technology still in the early stages of research and development (R&D) (Baker, Chon, & Keisler, 2009). CCS dominates electricity market share over time given a chemical looping breakthrough.

För att möjliggöra att Helsingborgs stad uppnår målet om klimatneutralitet till år 2030 har Öresundskraft beslutat att implementera en CCS-anläggning vid ett avfallseldat kraftvärmeverk i Helsingborg som idag står för ungefär 19 % av de direkta utsläppen i Helsingborg. Innan Öresundskraft planerar att påbörja byggnationen är det av intresse att undersöka klimatpåverkan för livscykeln för att förstå nettoeffekten av klimatnyttan som CCS-anläggningen skapar. Syftet med examensarbetet är följaktligen att undersöka klimatpåverkan för byggnation och drift av CCS-anläggningen samt klimatpåverkan för transport och geologisk förvaring av den avskilda koldioxiden. Klimatpåverkan för byggnation av anläggningen utfördes enligt ett bokföringsperspektiv där beräkningar genomfördes i Excel med klimatdata för respektive material som erhölls från digitala klimatdatabaser. Klimatpåverkan för driften av anläggningen samt nedströms delprocesser utfördes både enligt ett bokföringsperspektiv och ett konsekvensperspektiv. Då klimatpåverkan beräknades användes ett kvantifieringsverktyg baserat på livscykelmetodik som var framtaget i Excel. Genom en litteraturstudie kunde efterfrågad indata och redan tillgänglig data sammanställas och matas in i verktyget. Efter att modifieringar genomförts i verktyget kunde energianvändning och klimatpåverkan för driften undersökas för ett driftår och för anläggningens livstid. Resultatet visade att byggnationen av CCS-anläggningen står för ungefär 2 % av den totala klimatpåverkan under anläggningens livstid och uppgår till ungefär 8,9 kton CO2e. CCS-anläggningen behöver vara i drift i 30 dygn för att klimatpåverkan som byggnationen står för ska hinna kompenseras för. CCS-anläggningen kommer under sin livstid ge upphov till en total klimatpåverkan mellan 439 ton CO2e och 511 ton CO2e medan ungefär 2,5 miljoner ton biogen koldioxid kommer att geologiskt förvaras under samma period. Detta innebär att anläggningens totala klimatpåverkan netto uppgår till ungefär -2 miljoner ton CO2e. Eftersom driften av CCS-anläggningen kräver el får detta konsekvensen att andra producenter i elnätet behöver öka sin produktion för att både kompensera för den minskade exporten av el från Filbornaverket men även för att kompensera för elanvändningen i hamn och vid injektion till geologisk förvaring. Den totala klimatpåverkan för denna elproduktion står årligen för ungefär 42 kton CO2e och totalt efter 25 driftår för ungefär 1 miljon ton CO2e. Eftersom den totala klimatpåverkan för CCS-anläggningen är lägre än mängden biogen koldioxid som avskiljs och geologiskt förvaras bidrar anläggningen till att minska utsläppen av växthusgaser i Helsingborgs stad. Däremot motsvarar inte mängden avskild biogen koldioxid den mängd utsläpp av växthusgaser som årligen sker i Helsingborg. På grund av detta kommer implementeringen av en CCS-anläggning inte vara en tillräckligt stor åtgärd för att Helsingborgs stad ska uppnå målet om klimatneutralitet till året 2030 och således krävs även andra utsläppsminskande åtgärder för att klimatmålet ska uppnås. / In order to enable the city of Helsingborg to achieve the goal of climate neutrality by the year 2030, Öresundskraft has decided to implement a CCS plant at a waste-fired cogeneration plant in Helsingborg, which today accounts for approximately 19 % of the direct emissions in Helsingborg. Before Öresundskraft plans to start construction, it is of interest to investigate the climate impact for the life cycle to understand the net effect of the climate benefit that the CCS plant creates. The purpose of the thesis is therefore to investigate the climate impact for the construction and operation of the CCS facility as well as the climate impact for transport and geological storage of the separated carbon dioxide. The climate impact for construction of the facility was carried out according to an accounting perspective where calculations were carried out in Excel with climate data for the respective materials obtained from digital climate databases. The climate impact for the operation of the plant and downstream sub-processes was carried out both from an accounting perspective and a consequence perspective. When the climate impact was calculated, a quantification tool based on life cycle methodology was used, which was developed in Excel. Through a literature study, requested input data and already available data could be compiled and entered into the tool. After modifications were carried out in the tool, the energy use and climate impact of the operation could be examined for one year of operation and for the lifetime of the facility. The result showed that the construction of the CCS facility accounts for approximately 2 % of the total climate impact during the lifetime of the facility and amounts to approximately 8.9 kton CO2e. The CCS facility needs to be in operation for 30 days in order to compensate for the climate impact that the building is responsible for. The CCS facility will during its lifetime give rise to a total climate impact of between 439 ton CO2e and 511 ton CO2e, while approximately 2.5 million ton of biogenic carbon dioxide will be geologically stored during the same period. This means that the plant’s total net climate impact amounts to approximately minus 2 million ton CO2e. Since the operation of the CCS plant requires electricity, this has the consequence that other producers in the electricity grid need to increase their production to both compensate for the reduced export of electricity from the Filbornaverket but also to compensate for the use of electricity in the port and when injecting into geological storage. The total climate impact for this electricity production accounts annually for approximately 42 kton CO2e and in total after 25 years of operation for approximately 1 million ton CO2e. Since the total climate impact of the CCS facility is lower than the amount of biogenic carbon dioxide that is separated and geologically stored, the facility contributes to reducing the emissions of greenhouse gases in the city of Helsingborg. However, the amount of separated biogenic carbon dioxide does not correspond to the amount of greenhouse gas emissions that occur annually in Helsingborg. Because of this, the implementation of a CCS facility will not be a large enough measure for the city of Helsingborg to achieve the goal of climate neutrality by the year 2030, and thus other emission-reducing measures are also required for the climate goal to be achieved.

Metal Organic Frameworks (MOFs) are a class of porous materials that are predominantly obtained as powders and have been investigated as a solid sorbent for gas separation or carbon capture applications from combustion exhaust gases. The manufacturing of products with MOFs to use them for real life applications is still a major problem. The most common productization method used is to form pellets of the powder MOFs. This has a limitation on the product shape which makes it difficult for it to be used in gas separation applications. This study focuses on using additive manufacturing technique to give MOFs a lattice (mesh-like) geometry which is useful for gas separation applications as the mixture of gases would be able to pass through the lattice structure and be separated due to the inherent MOF properties and characteristics. Two MOFs based on magnesium and manganese salts have been studied in this project. An extrudable paste developed using alginate gel as a binder with these MOFs. With alterations in paste formulations and 3D printer parameters, lattice structures were printed using the two MOFs. CO2 and N2 gas uptakes were measured showing that the structure adsorbs CO2 gas to a higher extend which results in the separation of N2 gas in both materials. When compared to their pristine powder form, other properties of the MOFs such as crystallinity, microstructure, reusability and surface area remain to be preserved after being 3D printed in both cases.

Sweden’s municipalities are leading the green energy transition, in this study, a techno-economic evaluation was done for a number of carbon neutral scenarios for Växjö municipality’s future energy system, situated within Sweden’s projected energy demand development in 2030 and 2050. The municipality’s partially decentralized energy system relies heavily on interconnected electricity supply from the national grid, and fuels imports from other parts of Sweden. It was a matter of question: in which ways will future demand changes induce supply changes, and whether a future carbon neutral energy system will be less costly in a sustained-electricity supply condition? To answer this, a balanced energy reference system for the municipality was created from an actual energy balance, using an hour-by-hour dynamic energy analysis tool EnergyPlan. Afterward, a future energy demand projection for Växjö was stemmed from the Swedish Energy Agency (SEA) sustainable future scenarios for Sweden, based on an average inhabitant energy demand. Modelling results for Växjö carbon neutral scenarios showed that Växjö energy system will be sufficient to supply future heat demand but not electricity demand, nor transport and industrial fuels. While in the short-term being carbon neutral is more economically attainable without changes in electricity supply technologies, a projected electricity price and consumption increase, change the outcomes for a carbon neutral scenario based on Intermittent Renewable Energy (IRE) to be less costly in the long term.

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