The Ca-looping cycle is a chemical process that alternates capture and release of CO2 using a Ca-based sorbent which can be applied to hydrogen production by steam reforming. Adding sorbent particles to the reformer achieves nearly pure hydrogen with higher yields via the ‘sorption enhancement’ effect. The major disadvantage is deactivation of the sorbent following multiple cycles and suggested solutions have been incorporation of inert material and regeneration by hydration. This work investigates Ca-based sorbents with a focus on their use for steam reforming of liquid feedstock. Thermodynamic analysis was used to understand the equilibrium of the steam reforming of three different feedstocks with and without CaO as the sorbent. Addition of sorbent significantly increased the H2 yield and the H2 molar fraction for all three feedstocks. Inert material was incorporated into CaO and CaO derived from Ca-D-gluconate. The resulting sorbents were investigated using thermogravimetric analysis (TGA) and a bench scale reactor in combination with X-ray diffraction (XRD) and N2 adsorption. Incorporation resulted in a reduction in pores in the 50-100 nm size range and caused self-reactivation behaviour over multiple cycles. The capture capacity and morphology of the sorbent was altered by the CaO precursor but XRD spectra were not. In situ XRD coupled with Rietveld refinement yielded new insights into the mechanism of Ca-based carbonation and sorbent stability. Agreement between in situ XRD and TGA data was found for carbonation of CaO and Ca(OH)2, and the mechanism of CO2 capture in partially hydrated CaO was investigated. Ca(OH)2 formed CaCO3 without the CaO intermediate, and anisotropic diffraction peak broadening was observed in the partially hydrated sorbent. Steam reforming of ethanol and glycerol with and without a Ca-based sorbent was investigated using a novel reactor featuring a nichrome resistance wire with a heating element/catalyst double function. Wire morphology had significant impact on feedstock conversion and the activity of the wire could be increased using a redox pretreatment which caused the formation of chromium oxides on the wire surface. The addition of sorbent by coating resulted in CO2 capture but not sorption enhancement. The coating also hindered water gas shift and eroded with time on stream.

Geological storage of carbon dioxide (CO2) has potential to significantly reduce atmospheric emissions of greenhouse gases. However, challenges exist to the successful establishment of this process. These include estimating and understanding storage capacity as well as its economic viability. A large proportion of Europe’s potential storage capacity is to be found in large open aquifers. However, in times when the European carbon price is low, storage in depleted oil reservoirs may be required to make early commercial projects economically viable. Regulation will require that storage in these sites is well understood and it currently requires conformity of actual with modelled behaviour. In this thesis we consider two areas with direct implication for these issues. Firstly, we consider the effect of top-surface structure and heterogeneity upon the storage capacity of open aquifers. It is found that top-surface structure is more likely to decrease storage efficiency in models with low average reservoir dip and/or permeability. Heterogeneity is seen to reduce injectivity and reduce capacity in low permeability models but increase lateral spread of CO2 and storage efficiency in higher permeability cases. Both features can change storage capacity by more than a factor of two. Secondly, we undertake investigation into 1D solutions for three-phase flow problems representative of CO2 storage in depleted oil reservoirs. We begin by trying to determine rigorously the physical solution to three-phase flow problems that may have non-unique solutions using the third-order essentially non-oscillatory (ENO) numerical method. However, we demonstrate that ENO only produces first-order convergence in discontinuous solutions, which means rigorous analysis using our proposed methodology is not possible. We do, however, benchmark compositional three-phase, three-component ENO simulations against analytic solutions for the first time and demonstrate that ENO is still preferable to low-order numerical methods. Finally, we demonstrate the convergence of three-phase numerical solutions by comparing solutions with water-wet and oil-wet capillary pressure functions as the magnitude of the capillary pressure functions become small.

Conversion of carbon dioxide into useful products has become highly desirable in recent years in order to both mitigate carbon dioxide emissions to the atmosphere and develop non-fossil energy sources. A variety of methods exist for the electro-reduction of carbon dioxide in solution to useful products, such as carbon monoxide and hydrocarbons. However, none of these processes are able to directly convert carbon dioxide to carbon. In this thesis, the conversion of carbon dioxide into solid carbon via molten carbonate electrolysis has been investigated. Both the past literature and the present work have shown that carbon nanopowder can be produced via this process, so it is highly likely that the electro-deposited carbon obtained is a valuable product. Although this process has been known since the 1960s, there are still many areas where our knowledge of the process is lacking. Hence, this thesis is focussed primarily on the reactions occurring in the molten carbonate electrolyte, the properties of the electro-deposited carbon and the re-oxidation of the electro-deposited carbon. Using cyclic voltammetry carried out at platinum working electrodes, it was found that carbon was electro-deposited at the cathodic limit in the Li2CO3-Na2CO3 and Li2CO3-K2CO3 electrolytes at temperatures of ca. 600 °C and ca. 700 °C, probably by the following reaction: CO32- + 4e- → C + 3O2- One novel finding of this research is that carbon electro-deposition competed with other cathodic reactions at the cathodic limit, which included alkali metal formation, carbon monoxide formation and alkali metal carbide formation. However, the carbon electro-deposition reaction dominated over the other cathodic reactions once the metal working electrode surface had become covered with a layer of electro-deposited carbon. This was probably because a lower overpotential is required to deposit carbon onto carbon, as opposed to carbon onto metal. Moreover, the other cathodic reactions may have been catalysed by the bare metal working electrode surface before it became covered with carbon. Electrochemical re-oxidation of electro-deposited carbon was found to occur via a process consisting of at least two stages, which was deduced using cyclic voltammetry in conjunction with the re-oxidation of electro-deposited carbon via galvanostatic chronopotentiometry. These stages may have corresponded to the oxidation of portions of the carbon with different morphologies. Carbon was electro-deposited onto mild steel working electrodes via chronoamperometry in the Li2CO3-Na2CO3, Li2CO3-K2CO3 and Li2CO3-Na2CO3-K2CO3 electrolytes. The highest apparent electro-deposition rate obtained was 0.183 g/cm2.h at an applied potential of -2.98 V vs. Ag/AgCl, using the Li2CO3-K2CO3 electrolyte at 708 °C. The average current efficiencies obtained for carbon electro-deposition were: 74.4 % for Li2CO3-Na2CO3, 79.0 % for Li2CO3-K2CO3 and 51.2 % for Li2CO3-Na2CO3-K2CO3. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy revealed that the washed carbon deposits mostly consisted of fine quasi-spherical carbon particles, some as small as 60 nm in diameter. All of the electro-deposited carbon appeared to be amorphous.

As a sector, agriculture in the UK is responsible for 43% of the methane (CH4) and 80% of the nitrous oxide (N2O) emissions, greenhouse gases (GHG) with global warming potentials of 21 and 310, respectively. The UK government is providing financial subsidies to reduce GHG emissions, particularly in energy production. These subsidies primarily come in the form of feed-in tariffs (FITs) and renewable heat incentive (RHI) to the renewable energy industry. Given that the traditional, fossil-fuel based energy industry’s GHG footprint is 96% in the form of carbon dioxide (CO2), a policy based on renewable electricity and heat production is primarily rewarding CO2 abatement and fossil fuel substitution. This is appropriate for most renewable energy technologies except anaerobic digestion (AD) which, besides producing energy, also has the potential to abate substantial amounts of CH4 and N2O. Dairy farms produce large quantities of cattle slurry which are suitable for AD but have low energy potential, thus providing poor economic return on capital investment even after claiming the subsidies available. An alternative subsidy could be provided by marginal abatement cost (MAC) which gives a value for GHGs abated. This research shows that after incentives dairy farmers bear a marginal abatement cost of £27 tonne-1 CO2 eq. abated, a key factor in low uptake of on-farm AD in the UK.

In the UK, there are about 26 million houses and the government’s future plan is to build 3 million more by 2020 (BBC, 2008, Jason, 2011). As the demand for housing increases, especially for single occupant homes, the rate of energy consumption and, in effect, the proportion of CO2 emissions is on the rise. Successful sustainable energy strategies for domestic buildings can thus be an effective tool for mitigating these effects and achieving healthy building conditions. The main aim of the research are obtaining comfortable building spaces by reducing any overheating and reduce energy demand by using passive method which also will reduce the emission of CO2. Also this work aims to raise attention on the influence of the domestic sector on the amount of CO2 emissions by using low thermal mass construction. Thus, the research’s objectives are divided into firstly, investigate the opportunity of improving the Micronal Phase Change Material (MPCM) thermal conductivity and secondly, studying the influence of using enhanced MPCM for reducing overheating in lightweight building construction. This research investigates means of improving the thermal performance of the UKs existing and new domestic buildings stock. In order to increase thermal resistance and hence reduce heat losses, a new panel comprised of outer coating and thin layer or aerogel to increase thermal resistance was developed which could be added to the exterior walls of existing houses. This research results have shown from the experimental work when MPCM coupled with construction materials that the percentage of MPCM should not be above 50% otherwise it will reduce the potential benefit of the mixture to enhance thermal conductivity of MPCM. The best thermal conductivity was obtained by mixing 20% PCM, 75% Gypsum and 5% Silica with honeycomb, which gave a value of 0.306 W/mK. On the other hand, the best thermal conductivity was obtained using the clay by mixing 40% MPCM, 20% Clay and 40% cement, which gave a value of 0.253 W/mK. The simulation results shown that natural night ventilation could help reduce the overheating period to about 50% with the use of MPCM. Finally, The results of the new external wall panel that has been developed to improve the thermal performance have shown that through application of these panels a substantial reduction between 3 ºC to 5 ºC in the internal temperature.

The UK 2008 Climate Change Act transferred a global policy issue into national legislation, establishing unprecedented targets for reducing emissions justified by scientific evidence. The Act prompted a question: could such stretching targets be achieved? This question is addressed through an embedded case study within the East Midlands region between 2010-2011. The research makes an original contribution to knowledge, taking an interpretive, decentred approach to subnational climate policy implementation, focusing on the policy meanings created and acted upon during the introduction of the Cameron Government’s austerity and localism agendas. These meanings are recovered using a mix of conversational interviews and meeting observations with policy actors. Subnational climate policy met significant challenges in being translated into action, being seen as peripheral to local policy concerns. Managers attempted to ‘embed’ climate policy within local authority practice, but were met with resistance and passivity stemming from climate policy’s diverse meanings amongst policy actors. Performance management was important in symbolising rational policy-making, rather than for its instrumental effectiveness. This briefly raised the priority of climate policy, but where locally compelling political arguments for implementation were absent, programmes became vulnerable to budget cuts. With stronger local arguments focusing on kindred policy areas such as fuel poverty and reducing local authorities’ own energy use, vulnerability was reduced. Localism brought such arguments into focus, as regional partnerships weakened and the National Indicators performance management framework was removed. Responses to these developments highlighted how perceptions of the location and flow of power contributed to meaning construction. The shift to kindred policy aims brings into question the plausibility of climate change targets predicated on scientific evidence rather than local policy meanings. The endurance of local climate policy is explained as a policy myth, enabling short term continuity with the promise of longer term change.

China has seen tremendous economic growth in the past three decades, and in the order of eight to ten per cent since 2000. This development has come with ever increasing energy consumption, and thus emissions of greenhouse gases (GHG). This trend has been an important topic in the international climate negotiations under the United Nations Framework Convention on Climate Change; China is under constant pressure from other large economies to contribute to reversing the GHG emissions trend in order to avoid dangerous climate change. At the same time, the Chinese government has pursued an environmental and energy security agenda focussed at increasing the energy efficiency of its economy and the supply of energy from renewable sources. Alongside, a domestic climate change discourse has developed, and changed over time. This thesis examines elements of the country-specific political ecology in the area of greenhouse gas mitigation in China, looking closely at what climate change means in China, and discussing how this influences the development and institutionalisation of mitigation mechanisms. I take a political ecology approach to scrutinize the nature and evolution of a climate change discourse in China, and the influences and implications of existing governance structures and institutions that affect greenhouse gas mitigation in the country. Adopting mixed empirical methods comprising semi-structured interviewing, media and numerical data analyses, and participant observation in research processes close to the government, data was collected between 2008 and 2011. In five academic papers with distinctive angles, I show the importance of engaging deeply with the formative, distinctly Chinese political, economic and ecological environment when discussing mitigation in China. The Chinese climate change discourse has changed significantly in recent years, for example resulting in different discursively acceptable ways for the country to engage in mitigation. These meanings of climate change in China have developed through specific interactions of the political and academic spheres, based on Chinese understandings of nature and history (and China’s place in it), as well as with limited involvement of the media compared to western developed country cases. The notion of historical responsibility is a major component of what climate change means in China; in this thesis I therefore illuminate the numerical and conceptual ramifications of this part of the discourse, noting that the re-active nature of this frame, with China positioned against the developed countries, has not lend itself to support new mitigation action. Low carbon economy is another newer and now very important element of the discourse, a frame that locates China in an active, entrepreneurial subject position. My study on two cases – mitigation in the Beijing transportation sector and the introduction of seven local emission trading systems through a approach of governance through pilots – shows how this part of the discourse allows for the development of new mitigation approaches when they follow established institutions and governance mechanisms in a path-dependent manner. This thesis contributes to the research of global environmental change by advancing theoretical and practical ways of engaging with climate change in general, and mitigation in particular in China. It stresses the importance of considering the country-specific political ecology when formulating global climate change policy.

The UK’s policy commitment to an 80% reduction in CO₂ levels over 1990 levels by 2050 has framed much recent research and debates between policy-makers and industry about whether and how a transition to a low-carbon future can be achieved. The technical potential for improved energy efficiency and installation of low- and zero-carbon generation technologies in the built environment is, in theory, large enough to achieve the emissions reduction targets in this economic sector but it requires a step-change in technology deployment, with less well studied implications for the industry actors who predominate in the existing markets for housing refurbishment. A socio-technical approach is taken to investigating this problem, drawing on the academic traditions of Actor-Network Theory and Transitions to frame the problem: how can a policy-driven change be brought about in a highly diffuse system of actors, where large outcomes emerge as the result of millions of small-scale decisions? Parallels are drawn with the history of Market Transformation policies that have achieved improved energy efficiency of stocks of electrical appliances over time. In order to explore how a Market Transformation approach might work in the rather different context of housing refurbishment, three key aspects of this particular socio-technical system need to be explored: the technical potential and workings of technology deployment; the operation of several implicated markets; the nature of innovation in the relevant industry sectors. A review of the practical, technical issues encountered in pioneering low-carbon refurbishment projects reveals certain risks of under-performance and unintended consequences of poor implementation. Managing these risks requires a level of underpinning knowledge as well as good-quality workmanship, raising the question of how such knowledge can best be introduced into the fragmented roles and contractual relationships that characterise the industry. The market opportunities for the work are complicated by the number and interdependence of the markets involved, including markets for property transactions and markets for refurbishment work and technology installation. Information systems already exist at the point of property transactions in the form of the Energy Performance Certificate, but the greatest potential for change exists in the mainstream repair, maintenance and improvement market. Interviews with mainstream SME construction managers explain the reasons why the industry’s custom and practice is essentially conservative, but also provide insights into the situations in which innovation can thrive, rather than being resisted or subverted. A proposal for systemic change has at its core the coordination of monitoring information and learning experiences from a range of innovative demonstration projects, with implications for change at an institutional level as well as within the practices of the industry itself. The findings of the research are discussed in terms of the strategic implications they hold for industry and policy-making.

This research provides policy-relevant insights into how a mass-scale, equitable transition to the use of Advanced Biomass (cook) Stoves (ABSs) can be achieved in India, with the aim of improving public health, especially for women and children. The research uses socio-technical systems to provide a characterisation of transition processes, and governance to explain issues of power influencing transition. A review of previous government cook-stove programmes in India and China highlights governance shortcomings in the former, in particular a lack of functional links between layers of administration and poor engagement with community institutions and cooks. Primary data from West Bengal and Karnataka highlighted sophisticated, skilful, flexible and culturally context specific cooking practices. Reasons for apparent low demand for improved stoves, characterised as lock-in, are found to include a combination of risk aversion and habits, lack of affordability, low awareness of the health consequences, as well as a mis-match between the normative priorities of policy makers – currently health- and those of cooks. It is found that the majority of polluting emissions within households - as well as greenhouse gases - from cooking derive from poorer households. A sectoral carbon offset strategy is proposed as a means of funding subsidies for ABSs and programme support measures. Several large corporations have invested significant sums in technology development, community outreach and dissemination, resulting in sales of over 600,000 ABSs. Reasons for their involvement appear mixed. Their market-based activities have generally not reached poor households and there are questions about their ability to build viable businesses in this highly dispersed and heterogeneous sector. A fundamental dichotomy is highlighted between large, centralised cooking programmes and the diverse, complex and changing reality of cooking activities, beliefs and behaviours on the ground. The research concludes that functional multi-level and multi-actor governance structures would be required to achieve a mass-scale transition to clean cooking using ABSs, with a lead role for the public sector. A key component of future success will involve building structures that ensure the agency of cooks and account for their socio-cultural cooking practices in the processes of technology and programme design and implementation.