Biomass combustion can be seen as CO2 neutral, thereby biomass combustion plants can have negative CO2 emissions if retrofitted with post combustion capture (PCC) technology using liquid absorbents. Monoethanolamine (MEA) has been used for carbon capture in coal combustion plants but are not suitable for use in biomass combustion plants due to corrosion and high solvent regeneration cost. Instead, the hot potassium carbonate (HPC) process using potassium carbonate (K2CO3) as absorbent show better attributes in these aspects. Although, K2CO3 has slow reaction kinetics with CO2 which need to be improved using promoters. Piperazine is the most tested promoter but are hazardous to humans. Recent research has revealed promising alternatives, among these different amino acid salts such as glycine, proline, and isonipecotic acid which are chemically benign. Biomass flue gas composition vary depending on the biomass fuel characteristics. How this affects the degradation and potential formation of hazardous substances need to be studied further. Biomass combustion plants are generally equipped with flue gas condensation systems, making retrofitting more feasible due to increased system flexibility and energy recovery options. The operation costs of carbon capture and sequestration (CCS) in biomass combustion plants need to be monitored to optimize the plant revenue. To make implementation of HPC in biomass combustion plants a reality, piperazine should be used as promoter. Meanwhile, research should focus on improving the absorption rate in HPC process with more chemically safe promoters.

Fluids play a vital role in essentially all geologic environments and processes, and are the principal media of heat and mass transfer in the Earth. The properties of geologic fluids can be diverse, as fluids occur at conditions ranging from ambient temperatures and pressures at Earth's surface, to extreme temperatures and pressures in Earth's deep interior. Regardless the wide ranges of conditions at which geologic fluids occur, fluid properties are described and governed by the same fundamental thermodynamic relationships. Thus, application of thermodynamic principles and methods allows us to decipher the properties and roles of geologic fluids, to help understand geologic processes. Fluid inclusions in minerals provide one of the best available tools to study the compositions of geological fluids. Compositions of fluid inclusions can be determined from microthermometric measurements, based on the vapor-saturated liquidus conditions of model chemical systems, or by various microanalytical techniques. The vaporsaturated liquidus relations of the system H2O-NaCl-CaCl2 have been modeled to allow estimation of fluid inclusion compositions by either microthermometric or microanalytical methods. Carbon capture and storage (CCS) in deep saline formations represents one option for reducing anthropogenic CO2 emissions into Earth's atmosphere. Availability of storage volume in deep saline formations is a significant component of injection and storage planning. Investigation of the volumetric properties of CO2, brine and CO2-saturated brine reveals that storage volume requirements are minimized when CO2 dissolves into brine. These results suggest that a protocol involving brine extraction, CO2 dissolution and re-injection may optimize CCS in deep saline formations. Numerical modeling of quartz dissolution and precipitation in a sub-seafloor hydrothermal system was used to understand the role of fluid-phase immiscibility ("boiling") on quartz-fluid interactions, and to predict where in the system quartz could deposit and trap fluid inclusions. The spatial distribution of zones of quartz dissolution and precipitation is complex, owing to the many inter-related factors controlling quartz solubility. Immiscibility exerts a strong control over the occurrence of quartz precipitation in the deeper regions of fluid circulation. / Ph. D.

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

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.

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.

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.

Sverige har som ambition att uppnå nettonollutsläpp av fossilt CO2 till år 2045. För att lyckas med detta ska landet minska sina utsläpp med 85%, samtidigt som så kallade kompletterande åtgärder kommer vidtas för att kompensera för resterande 15%. Denna studie utreder Sveriges arbete med negativa utsläpp som kompletterande åtgärd med fokus på teknikerna bio-energy for carbon capture and storage (Bio-CCS på svenska), Direct air capture for carbon capture and storage (DACCS) och biokol. Även carbon capture and storage (CCS), som kan bidra till att göra anläggningar CO2-neutrala, har studerats. Under arbetets gång har en litteraturstudie samt intervjuer med forskare, politiker, bransch- och företagsrepresentanter samt myndigheter genomförts.  För CCS och Bio-CCS, som innefattar avskiljning av CO2 från punktutsläpp, finns fyra olika avskiljningsstrategier som kallas post-, pre-, och oxyfuel combustion samt chemical looping. I fallet med DACCS tillämpas antingen absorption eller adsorption för att avskilja koldioxiden från atmosfären. Biokol produceras genom förbränning av biomassa i en pyrolysanläggning och kan sedan användas som jordförbättringsmedel och kolsänka. Det finns idag en inhemsk biokolsproduktion på kommersiell skala vilket gör att biokol skiljer sig från de övriga tre teknikerna som inte kommit lika långt i sin utveckling. Däremot finns det ett flertal pilotprojekt inom CCS och Bio-CCS i Sverige.  Sveriges väletablerade bioekonomi gör att det finns goda förutsättningar för biokol och Bio- CCS att bidra till negativa utsläpp ur ett 2045-perspektiv. DACCS anses däremot inte aktuellt som kompletterande åtgärd till år 2045. Efter intervjuer framgår att det råder en god samstämmighet mellan olika aktörer kring vilka faktorer som behöver behandlas för att implementera teknikerna. Gemensamt för alla tekniker är att det krävs ekonomiska incitament för att möjliggöra storskalig implementering. För CCS-teknikerna krävs även regulatoriska förändringar för att underlätta transporten av CO2. / Sweden's ambition is to achieve net zero emissions of fossil CO2 by the year 2045. To reach this target, Sweden aims to reduce its emissions by 85%, while so-called supplementary measures will be taken to compensate for the remaining 15%. This study investigates Sweden's work with negative emissions as a complementary measure with a focus on the technologies bio-energy for carbon capture and storage (Bio-CCS in Swedish), Direct air capture for carbon capture and storage (DACCS) and biochar. Carbon capture and storage (CCS), which can help make industrial plants CO2-neutral, has also been studied. During the project, a literature study and interviews with researchers, politicians, industry and company representatives as well as authorities were carried out, which formed the basis of the report.  For CCS and Bio-CCS, which include separation of CO2 from point source emissions, there are four different separation strategies called post-, pre-, and oxyfuel combustion as well as chemical looping. Among these, post combustion is highlighted as the most developed. In the case of DACCS, either absorption or adsorption is applied to separate CO2 from the atmosphere. CCS, Bio-CCS and DACCS all have in common that the captured CO2 must be stored in deep geological formations once it has been separated. Biochar is produced by heating biomass in a pyrolysis plant and can be used as a soil improver and carbon sink. Today Sweden has a domestic biochar production on a commercial scale, which means that biochar differs from the other three technologies that have yet to reach that stage of development. However, there are several pilot projects within Bio-CCS and CCS in Sweden.  Sweden's well-established bioeconomy means that the conditions are good for biochar and Bio-CCS to contribute to negative emissions in relation to the 2045 target. DACCS, on the other hand, is not considered relevant as a supplementary measure to the year 2045 due to its technical immaturity and high cost. From interviews with researchers, authorities, companies, industry organizations and politicians, it is clear that there is a consensus between the different actors on which factors need to be addressed in order to enable large-scale implementation of the technologies. Common to all technologies is that financial incentives are required to enable large-scale implementation. The CCS technologies also require regulatory changes to facilitate the transport of CO2.

Yes / The process of capturing and storing carbon dioxide (CCS) was previously considered a crucial and time-sensitive approach for diminishing CO2 emissions originating from coal, oil, and gas sectors. Its implementation was seen necessary to address the detrimental effects of CO2 on the atmosphere and the ecosystem. This recognition was achieved by previous substantial study efforts. The carbon capture and storage (CCS) cycle concludes with the final stage of CO2 storage. This stage involves primarily the adsorption of CO2 in the ocean and the injection of CO2 into subsurface reservoir formations. Additionally, the process of CO2 reactivity with minerals in the reservoir formations leads to the formation of limestone through injectivities. Carbon capture and storage (CCS) is the final phase in the CCS cycle, mostly achieved by the use of marine and underground geological sequestration methods, along with mineral carbonation techniques. The introduction of supercritical CO2 into geological formations has the potential to alter the prevailing physical and chemical characteristics of the subsurface environment. This process can lead to modifications in the pore fluid pressure, temperature conditions, chemical reactivity, and stress distribution within the reservoir rock. The objective of this study is to enhance our existing understanding of CO2 injection and storage systems, with a specific focus on CO2 storage techniques and the associated issues faced during their implementation. Additionally, this research examines strategies for mitigating important uncertainties in carbon capture and storage (CCS) practises. Carbon capture and storage (CCS) facilities can be considered as integrated systems. However, in scientific research, these storage systems are often divided based on the physical and spatial scales relevant to the investigations. Utilising the chosen system as a boundary condition is a highly effective method for segregating the physics in a diverse range of physical applications. Regrettably, the used separation technique fails to effectively depict the behaviour of the broader significant system in the context of water and gas movement within porous media. The limited efficacy of the technique in capturing the behaviour of the broader relevant system can be attributed to the intricate nature of geological subsurface systems. As a result, various carbon capture and storage (CCS) technologies have emerged, each with distinct applications, associated prices, and social and environmental implications. The results of this study have the potential to enhance comprehension regarding the selection of an appropriate carbon capture and storage (CCS) application method. Moreover, these findings can contribute to the optimisation of greenhouse gas emissions and their associated environmental consequences. By promoting process sustainability, this research can address critical challenges related to global climate change, which are currently of utmost importance to humanity. Despite the significant advancements in this technology over the past decade, various concerns and ambiguities have been highlighted. Considerable emphasis was placed on the fundamental discoveries made in practical programmes related to the storage of CO2 thus far. The study has provided evidence that despite the extensive research and implementation of several CCS technologies thus far, the process of selecting an appropriate and widely accepted CCS technology remains challenging due to considerations related to its technological feasibility, economic viability, and societal and environmental acceptance.

Yes / Capturing and storing CO2 (CCS) was once regarded as a significant, urgent, and necessary option for reducing the emissions of CO2 from coal and oil and gas industries and mitigating the serious impacts of CO2 on the atmosphere and the environment. This recognition came about as a result of extensive research conducted in the past. The CCS cycle comes to a close with the last phase of CO2 storage, which is accomplished primarily by the adsorption of CO2 in the ocean and injection of CO2 subsurface reservoir formation, in addition to the formation of limestone via the process of CO2 reactivity with reservoir formation minerals through injectivities. CCS is the last stage in the carbon capture and storage (CCS) cycle and is accomplished chiefly via oceanic and subterranean geological sequestration, as well as mineral carbonation. The injection of supercritical CO2 into geological formations disrupts the sub-surface’s existing physical and chemical conditions; changes can occur in the pore fluid pressure, temperature state, chemical reactivity, and stress distribution of the reservoir rock. This paper aims at advancing our current knowledge in CO2 injection and storage systems, particularly CO2 storage methods and the challenges encountered during the implementation of each method and analyses on how key uncertainties in CCS can be reduced. CCS sites are essentially unified systems; yet, given the scientific context, these storage systems are typically split during scientific investigations based on the physics and spatial scales involved. Separating the physics by using the chosen system as a boundary condition is a strategy that works effectively for a wide variety of physical applications. Unfortunately, the separation technique does not accurately capture the behaviour of the larger important system in the case of water and gas flow in porous media. This is due to the complexity of geological subsurface systems, which prevents the approach from being able to effectively capture the behaviour of the larger relevant system. This consequently gives rise to different CCS technology with different applications, costs and social and environmental impacts. The findings of this study can help improve the ability to select a suitable CCS application method and can further improve the efficiency of greenhouse gas emissions and their environmental impact, promoting the process sustainability and helping to tackle some of the most important issues that human being is currently accounting global climate change. Though this technology has already had large-scale development for the last decade, some issues and uncertainties are identified. Special attention was focused on the basic findings achieved in CO2 storage operational projects to date. The study has demonstrated that though a number of CCS technologies have been researched and implemented to date, choosing a suitable and acceptable CCS technology is still daunting in terms of its technological application, cost effectiveness and socio-environmental acceptance.

The objective of this study is to conduct a critical evaluation of the environmental law framework applicable to carbon capture and storage (hereafter CCS) in South Africa. The discussion begins by confirming that CCS has a place in environmental law as a mitigation measure. The inclusion of CCS in the clean development mechanism could incentivise the development of environmental law frameworks for CCS in South Africa. Implementation of CCS is gradual, with only eight large scale integrated CCS projects having been established around the world. An appreciation of key scientific concepts is helpful for an understanding of the CCS process. The CCS project life cycle and related impacts on the environment provide a context for discussion of the legal requirements accompanying the CCS life cycle. The Constitution of the Republic of South Africa, 1996 and the National Environmental Management Act 107 of 1998 constitute appropriate framework legislation for CCS. Decision 3/CMP.1, Modalities and procedures for a clean development mechanism as defined in Article 12 of the Kyoto Protocol adopted by the Conference of the Parties serving as the Meeting of the Parties to the Kyoto Protocol held at Montreal from 28 November to 10 December 2001 March 2006 provides international legal requirements accompanying the project life cycle against which the South African legal framework is examined. Some provisions of additional South African laws and policies will be applicable to CCS depending on the nature of the specific CCS project, but specific regulations may have to be developed for South Africa. Policy documents have been gradually bringing clarity to the way forward in arriving at a legal framework for CCS, and by reference to existing local legislation and international guidance, an environmental law framework for CCS can be developed for South Africa. / LLM (Environmental Law and Governance), North-West University, Potchefstroom Campus, 2014