University, Diss., 2005--Potsdam.

Technologies considered for separating CO₂ from flue gas and injecting CO₂ into saline aquifers are energy intensive, costly, and technically challenging. Production of dissolved natural gas and geothermal energy by extraction of aquifer brine has shown the potential of offsetting the cost of CO₂ capture and storage along with other technical and environmental advantages. The key is to recognize inherent value in the energy content of brine in many parts of the world. Dissolved methane in brine and geothermal energy are two of the sources of energy of many aquifers. For example, geopressured-geothermal aquifers of the US Gulf Coast contain sheer volume of hot brine and dissolved methane. For the same reason, the capacity of these geopressured-geothermal aquifers for storage of CO₂ is remarkable. In this study, various reservoir models were developed from data of Texas and Louisiana Gulf Coast saline aquifers. A systematic study was performed to determine the range of uncertainty of the properties and the prospective of energy production from saline aquifers. Two CO₂ injection strategies were proposed for storage of CO₂ based on the results of simulation studies. Injection of CO₂-saturated brine showed several advantages compared to injection of supercritical CO₂. An overall energy analysis was performed on the closed-loop cycles of capture from power plants, storage of CO₂, and production of energy. The level of cost offset of CCS technology by producing energy from target aquifers strongly depends on the applications of the produced energy. The temperature of the produced brine from geopressured-geothermal aquifers is higher than the temperature of amine stripper column. Calculations for the strategy of injecting CO₂-saturated brine show that the amount of extracted thermal energy from geopressured-geothermal aquifers exceeds the amount of heat required for capturing CO₂ by amine scrubbing. In the process of injecting dissolved CO₂, compressors and pumps should run to pressurize the CO₂ and brine to be transported and achieve the required wellhead pressure. The preliminary estimations indicate that the produced methane provides more energy than that required for pressurization. In the regions where the temperature gradient is normal, the temperature of the produced brine may not be high enough for using in the chemical absorption processes. Separation mechanisms driven by pressure difference are the alternatives for chemical absorption processes since the produced methane can be burned for running the compressors and pumps. Membrane process seems to be the leading technology candidate. The preliminary estimations show that the produced power by extracted methane and geothermal energy exceeds the power needed for membranes, compressors, and pumps. Neither storage of greenhouse gases in saline aquifers nor production of methane and/or geothermal energy from these aquifers are profitable. However, designing a closed looped system by combining methods of capture, storage and production may pay off the whole process at least from the energy point of view. / text

Carbon Capture and Storage (CCS) has been identified as a feasible technology to reduce CO2 emissions whilst permitting the continued use of fossil fuels. Injected CO2 must remain efficiently isolated from the atmosphere on a timescale of the order of 10000 years and greater. Natural CO2-rich sites can be investigated to understand the behaviour of CO2 in geological formations on such a timescale. This thesis examines the reservoir and seal on one such oilfield. Several hydrocarbon fields in the South Viking Graben of the North Sea naturally contain CO2, which is thought to have charged from depth along the western boundary fault of the graben. The Miller oil field which contains ~ 28 mol% CO2, of isotopic composition δ13C = -8.2‰. The Upper Jurassic Brae Formation reservoir sandstones and the Kimmeridge Clay Formation (KCF) seal have been exposed to the CO2 accumulation since its emplacement. Rock samples from the reservoir sandstone and bottom of the seal mudrock were examined using multiple techniques, including XRD, SEM, fluid inclusion and carbonate stable isotope analyses. The sandstones show no features directly attributable to abundant CO2 charge. SEM analyses reveal significant heterogeneities in diagenesis within the KCF. The silt/sand lithologies of the KCF have undergone a diagenetic history similar to that of the Brae Formation sandstones. In contrast, the KCF shales display a distinctly different diagenesis of dominant dissolution of quartz and feldspar with little evidence of mineral precipitation. In both the Brae Formation and the KCF, pore-filling kaolinite, illite and carbonates are relatively late diagenetic events which can be associated with CO2-induced feldspar dissolution. Mudrock X-ray diffraction mineralogical data reveal abrupt vertical mineralogical variations across the reservoir crest in the Miller Field, while such variations are absent in a low-CO2 control well in the same geological settings. This suggests that reactions induced by abundant CO2 dissolved feldspar and produced kaolinite, carbonates and quartz in the seal, while oil emplacement inhibited the reactions in the oil leg. However, petrographic evidence and comparison between different sections argue against CO2 reactions as the sole cause for such large mineralogical variations, especially for quartz. The vertical mineralogical variations to a certain extend represent original sedimentary heterogeneity. Linear variations of carbonate δ13C with depth were discovered in both shale and silt/sand lithologies of the KCF in a 12m zone immediately above the reservoir. These features are absent in the low-CO2 control well. These trends are interpreted as dissolution of original carbonates by CO2 slowly ascending from the reservoir. New carbonates precipitated from a carbon source with upwards decreasing δ13C due to mixing between three carbon sources with different C isotopes at systematically varying ratios. The isotopes in the reservoir and the bottom of the seal suggests initial CO2 charge at about 70-80 Ma. CO2 infiltration rate is estimated at about 9.8×10-7g·cm-2·y-1. Geochemical modelling was applied to reconstruct the reservoir fluid evolution by calibrating it to mineralogy, fluid chemistry, diagenesis and fluid inclusion data. The modelling suggests that CO2 migrated into the reservoir together with a saline basinal fluid derived from the underlying evaporites at ~ 70 Ma. The CO2 and basinal water charge imposed an important influence on the mineral reactions and fluid chemistry. This study suggests that the KCF has formed an excellent CO2 seal, with no substantial breach since its charge at 70-80 Ma.

This thesis progresses from a ‘science and technology studies’ (STS) perspective to consider the ways that expert stakeholders perceive and communicate uncertainties and risks attached to carbon dioxide (CO2) capture and storage (CCS) research and development, and how this compares with policy framings and regulatory requirements. The work largely falls within the constructivist tradition in sociology, but also draws on literature from the philosophy of science and policy-­‐oriented literature on risk and uncertainty. CCS describes a greenhouse gas (GHG) mitigation technology system that involves the capture, pressurisation, transportation, geological injection and long-­‐term storage of CO2 as an alternative to atmospheric emissions. Only few and relatively small applications exist at the moment and research efforts are on going in many countries. The case for developing CCS towards large-­‐scale, commercial deployment has largely been presented as follows since the mid-­‐ 1990s: climate change mitigation is the developed world’s historical responsibility and must be addressed urgently; chief amongst GHGs is CO2, which makes up more than three quarters of emissions; the vast majority of CO2 is emitted from the combustion and gasification of hydrocarbons – oil, gas and coal – for energy generation; transitioning away from these high-­‐CO2 primary energy sources will likely take several decades at the least; therefore, CO2 capture systems should be designed for power and industrial emissions in developed countries, as well as emerging economies where energy suppliers will continue to construct relatively cheap and well understood high-­‐CO2 generation plants. The development of large-­‐scale CO2 capture has thus arisen from a concern with engineering a technological system to address a CO2 legacy in the developed world, and a high-­‐CO2 trajectory in developing/emerging countries, rather than on the back of purely scientific curiosity. And the potential for large-­‐scale development has been presented on the back of a variety of scientific and technical evidence, as well as the urgency of the policy objective and related aims. Research activities, often concentrated around technology demonstration projects, are the primary focus of the first part of this thesis. In the second part I consider the extent to which research has shaped policy developments, and how regulations have subsequently informed a more detailed research agenda. I follow a ‘grounded theory’ methodology as developed by Glaser and Strauss (1967) and take additional guidance from Glaser’s (1992) response to Strauss’ later writings as well as Charmaz (2006) and Rennie (2000), and use a mix of qualitative and quantitative analytical methods to assess my data. These include information from 60 semi-­‐structured interviews with geoscientists and policy stakeholders; close readings of scientific publications, newspaper articles, policies and regulatory documents; statistical evidence from a small survey; quantitative analysis of newspaper articles; and social network analysis (SNA) of scientific co-­‐authorship networks. Theory is drawn from STS literature that has been appropriate to address case study materials across each of the 7 substantive chapters. The first section of the thesis considers expert claims, with a focus on geoscience research, and draws on literature from the closely related ‘social shaping of technology’ (SCOT) and ‘sociology of scientific knowledge’ (SSK) programmes, as well as Nancy Cartwright’s philosophy of science. The second half of the thesis draws on the ‘co-­‐production’ framework and Wynne’s (1992) terminology of risk and uncertainty, to assess relations between risk assessment and risk management practices for CCS. I likewise draw on literature from the ‘incrementalist’ tradition in STS to ask whether and how understandings of technology risk, governance and deployment could be improved. Each chapter presents new empirical material analysed with distinct reference to theories covered in the introduction. Chapter 2 provides a general overview of the history, technology, economics and key regulatory issues associated with CCS, which will be useful to assess the theoretically driven arguments in subsequent chapters. Chapter 3 draws on the concept of ‘interpretive flexibility’ (Pinch and Bijker 1984) to assess a range of expert perceptions about uncertainties in science, technology and policy, and I develop a substantive explanation, ‘conditional inevitability’, to account for an epistemic tension between expressions of certitude and the simultaneous acknowledgement of several uncertainties. Chapter 4 continues the enquiry into stakeholder perceptions and draws on Haas’ notion of ‘epistemic communities’ (Haas 1992) to assess geoscientists’ work practices. I complement this framing with a close look at how uncertainty is treated in simulation modelling and how conclusions about storage safety are formulated, by drawing on Nancy Cartwright’s philosophy of science (Cartwright 1999) and Paul Edwards’ account of complex system modelling for climate change (Edwards 2010). The chapter shows how shared understandings of adequate evidence and common analytical tools have been leveraged to present relatively bounded and simple conclusions about storage safety, while geoscientists nevertheless recognise a high degree of uncertainty and contingency in analyses and results. Chapter 5 continues the focus on knowledge production in the geosciences and is supported by SNA data of workflow patterns in the Sleipner demonstration project. The analysis shows how a few actors have had a pivotal role in developing insights related to storage safety particularly on the back of seismic monitoring and other data acquired through industry partnerships. I therefore continue the chapter with a deconstruction of how seismic data has been used to make a case for the safety of CO2 storage, again drawing on Cartwright and others (Glymour 1983) to explain how individual findings are ‘bootstrapped’ when conclusions are formulated. I show how a general case about storage safety has emerged on the back of seismic data from Sleipner as well as a shared understanding among geoscientists of how to account for uncertainties and arrive at probable explanations. Chapter 6 considers to what extent scientific research has given shape to, and in turn been shaped by, CCS policy and regulations in the EU, drawing on Wynne’s (1992) terminology of risk and uncertainty as well as legal scholarship (Heyvaert 2011). I conclude that a ‘rational-­‐instrumental’ interpretation of uncertainty and precaution has furnished a compartmentalised understanding of risk assessment and risk management practices. Chapter 7 continues to look at the ways that risk assessment methodologies influence risk management practices through a case study of the Mongstad CCS demonstration project in Norway. I draw on ‘incrementalist’ literature (Lindblom 1979; Woodhouse and Collingridge 1993) to consider alternative conceptualisations of technology development and risk management when expectations clash with scientific uncertainties and criticism. Chapter 8 draws on insights from across STS (Downs 1972; Collingridge and Reeve 1986; Wynne 1992) to create a novel conceptual model that accounts for recent years’ developments in CCS governance. Here I conclude that setbacks and criticisms should be expected when analyses have largely presented CCS as a technical problem rather than a socially contingent system. Following Stirling (2010) I conclude that scientists and policymakers should instead strive to present complexity in their analyses and to engage with wider publics (Yearley 2006) when technical analysis is inseparable from socially mediated indeterminacies (Wynne 1992), to increase the chance of more successful engagement practices (Wynne 2006). The conclusions at the end of the thesis seek to draw out interpretive and instrumental lessons learned throughout.

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No description available.

In an effort to reduce atmospheric carbon dioxide (CO2) emissions and mitigate climate change, it has been proposed to sequester supercritical CO2 in underground saline aquifers. Geological storage of CO2 involves different trapping mechanisms which are not yet fully understood. In order to improve the understanding of the effect of chemical reaction on the flow and transport of CO2, these storage mechanisms are modelled experimentally and numerically in this work. In particular, the destabilising interaction between the fluid hydrodynamics and a density-increasing second-order chemical reaction is considered. It is shown that after nondimensional scaling, the flow in a given physicochemical system is governed by two dimensionless groups, Da/Ra2, which measures the timescale for convection compared to those for reaction and diffusion, and CBo', which reflects the excess of the environmental reactant species relative to the diffusing solute. The destabilising reactive scenario is modelled experimentally under standard laboratory conditions using an immiscible two-layer system with acetic acid acting as the solute. A novel colorimetric technique is developed to infer the concentrations of chemical species from the pH of the solution making it possible to measure the flux of solute into the aqueous domain. The validity of this experimental system as a suitable analogue for the dissolution of CO2 is tested against previous work and the destabilising effect of reaction is investigated by adding ammonia to the lower aqueous layer. The system is also modelled numerically and it is shown that the aqueous phase reaction between acetic acid and ammonia can be considered to be instantaneous, meaning that Da/Ra2 tends to infinity and the flow is therefore governed only by the initial dimensionless concentration of reactant in the aqueous phase. The results from the experiments and numerical simulations are in good agreement, showing that an increase in the initial concentration of reactant increases the destabilising effect of reaction, accelerates the onset of convection and enhances the rate of dissolution of solute. The numerical model is then applied to a real world aquifer in the Sleipner gas field and it is demonstrated how the storage capacity of a potential CO2 reservoir could be enhanced by chemical reaction.

Geological carbon dioxide (CO2) storage in the United Kingdom (UK) will likely be entirely offshore, which may lead to the production and disposal into the sea of reservoir waters to increase storage capacity, or through CO2-Enhanced Oil Recovery (CO2-EOR). These produced waters have the potential to contain significant concentrations of trace metals that could be of harm to the environment. Batch experiments with CO2, warm brines, and reservoir sandstones were undertaken for this thesis to determine concentrations of 8 trace metals (arsenic, cadmium, chromium, copper, mercury, nickel, lead, zinc) which could be leached during CO2 storage in 4 UK North Sea hydrocarbon reservoirs. A sequential extraction procedure (SEP) was also used to determine the potential mobility of these metals under CO2 storage from mineral phases making up the reservoir samples. The results broadly showed that mobilised trace metal concentrations were low (parts per billion, ppb) in the batch experiments, with the exceptions of nickel and zinc. These metals were associated with carbonate and some feldspar dissolution, with other metals apparently desorbed from mineral surfaces, probably clays. The results of the SEP, however, were a poor predictor of actual mobility with respect to the batch experiments, although useful in determining the distribution of trace metals within the defined mineral phases (water soluble, ion exchangeable, carbonate, oxide, sulphide, silicate). In addition, fieldwork was carried out at Green River, Utah, to collect 10 CO2-driven spring water samples and 5 local aquifer rock samples. This area was used as a natural analogue for CO2-mobilised trace metals from sandstone aquifers. Trace metal concentrations in spring waters were very low (ppb) and batch experiments using Utah rock samples, spring water collected from Crystal Geyser, and CO2 confirmed very low mobility of these metals. The SEP was repeated for the Utah reservoir rocks, but again was not a reliable predictor for actual mobility, other than to confirm that overall bulk concentrations of trace metals was low. Comparison of trace metal concentrations from the batch experiments with data from UK North Sea oil and gas produced waters shows that overall, concentrations mobilised in batch experiments are within the range of concentrations across all North Sea fields reporting their data. However, on a field-by-field basis, some CO2 mobilised concentrations exceeded those currently produced by oil and gas activities. Furthermore, average batch experiment trace metal loads are higher than average oil and gas produced waters, and in some cases exceed international guidelines. Therefore, while the majority of trace metals have low mobility and therefore low environmental impact, this should be assessed on a case-by-case basis. Regular monitoring of dissolved constituents in produced waters carried should also be carried out, particularly in the initial stages of CO2 storage operations, with remedial action taken as required to reduce the environmental impact of offshore carbon capture and storage.

Carbon Capture and Storage (CCS) is a legitimate technology option that should be part of a balanced portfolio of mitigation technologies available Post-Kyoto Protocol framework after Paris 2015 and beyond the 2020s or the cost achieving 2 degrees Celsius stabilisation scenario will significantly increase. Oxy-fuel combustion as a CCS technology option increases fuel flexibility. Additionally, oxy-biomass as a bio-energy with CCS (BECCS) technology can achieve negative carbon dioxide (CO2) emissions in sustainable biomass systems. Also, oxygen (O2) production in an air separation unit (ASU) gives potential for extra operational flexibility and energy storage. In this work, new designs of 20 litre spherical (R-20) and 30 litre non-spherical (R-30) ignition chambers have been built at the University of Edinburgh to carry-out dust ignition experiments with different ignition energies for evaluating pulverised fuel ignitability as a function of primary recycle (PR) O2 content for oxy-fuel PF milling safety. A set of coals and biomasses being used (at the time of submitting this work) in the utility pulverised fuel boilers in the UK have been employed. Coal and biomass dusts were ignited in air and oxy-fuel mixtures up to 30 % v/v O2 balance mixture CO2 where peak pressures (Pmax) from ignition were recorded. Pressure ratios (Pmax/Pinitial) were determined the key parameter for positive ignition identification with a value above 2.5 to be considered positive. Particle size effects in coal and biomass ignition were evaluated. Results on biomass were more variable than with coals, requiring a stronger ignition source (5,000 J) mainly due to larger particle sizes. Finer biomass particles behaved similarly to air ignition in 25 % v/v O2 in CO2. Larger particles of biomass did not ignite at all for most cases even reaching 30 % v/v O2 in CO2. A reference coal used, El Cerrejon, behaved as expected with 30 % v/v O2 balance CO2 matching air case; particles between 75-53 microns had lower ignitability than finer below 53 microns but were critical in devolatilisation. Most fuels did not ignite in 21 % v/v in CO2 below 200 g/m3 concentrations. The use of adequate ignition energy strength is needed for the PF mill safety case, with 5,000 J energy required for the biomasses tested. An indication of potential ignition chamber volume and geometry effect has also been observed when comparing results from R-20 and R-30 ignition chambers. Important implications include that oxy-biomass PR with 21 % v/v O2 content would give improved pulverised fuel (PF) milling safety when compared to air firing but reduced ignitability and a 25 % v/v O2 balance CO2 atmosphere would approach to oxy-biomass ignition behaviour in air in mills.

This thesis explores the international political dynamics of developing low carbon technology. Specifically, Carbon Capture and Storage (CCS) technology as a climate mitigation strategy in a developing country context is examined. CCS is a technological solution that allows for the continued use of fossil fuels without the large amounts of associated CO2 emissions. This entails capturing the CO2 emitted from large point sources, such as a coal-fired power station, and transporting the captured emissions to be injected and stored permanently into geological media. Consequently, CCS is a bridging technology that could provide more time for transitioning to a low-carbon economy. A case study of India is used, which is an emerging industrialising economy, and is also the third-largest coal producer in the world. India faces a dilemma: poverty alleviation and infrastructure development to support its billion plus population requires vast amounts of energy, which is predominantly based on fossil fuels. Therefore, it was envisioned that CCS would be a sustainable option, which could enable industrialisation at the rate required, whilst preventing the exacerbation of the negative effects of climate change. However, during the period of study (2007-2010), CCS was not embraced by India, despite there being a growing impetus to develop, demonstrate and transfer the technology. India was reluctant to consider CCS as part of a mitigation strategy, and this thesis focuses on the reasons why. An interdisciplinary approach is used, coupling perspectives from science, technology and innovation studies (STS) with concepts from International Relations (IR) scholarship. This sociotechnical conceptual framework is applied to gain a more holistic picture of the failed attempt to transfer CCS technology to India. Key technical challenges and blockages are identified within India’s existing energy system, which have restricted CCS technology implementation. In addition, the political challenges associated with the rejection of CCS by the Indian Government are explored. Empirical evidence is on the basis of elite interviews, an expert stakeholder survey and relevant documents. Another case study on the Cambay basin is used to further demonstrate the influence of political factors on CCS implementation, even in an area considered to have suitable technical conditions. The outcomes of this study have implications for policy addressing global challenges, especially by means of international cooperation and technological change.