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ON 16 NOVEMBER 2000, the final report of the World Commission on Dams (WCD) was launched in London, in the presence of South Africa’s former president Nelson Mandela. This represented a remarkable milestone in the history of dam policy and politics. During its two-year existence, WCD had conducted the most extensive review of research and evidence regarding the planning, impacts, and management of large dams. It had engaged with numerous stakeholders around the globe. It also made comprehensive recommendations about how to improve dam planning and management.

From the British debate on the depletion of coal in 1865 to the First World Power Conference held in London in 1924, scientists, engineers, industrialists, and politicians produced new interpretations of the past, present, and future in terms of the mobilisation of energy resources. This thesis identifies an emerging ‘energy developmentalism’, which called for maximising energy use to maintain or improve a nation’s place in international competition. Energy developmentalism was not a marginal worldview confined to ‘energeticists’, but a coherent set of claims, measurements, and arguments that informed energy governance on an international scale. Rather than focusing on a single resource, energy developmentalism applied a unified schema to all energy sources, including those like solar and tidal energy that were still mostly theoretical. Drawing on sources from across Europe, while staying grounded in political changes in Britain and France, makes it possible to understand how a general formula for transforming raw materials with maximum efficiency was applied differently depending on specific political contexts. This period saw the articulation of problems like the depletion of resources, the difference between renewable and nonrenewable energy, the intermittency of renewables, the overreliance on a single source of energy, and the centrality of energy to modern economies – problems that are often associated with later periods. Scientific measurements of efficiency, horsepower, and kilowatts became operators in political debates centred on questions of national standing and progress. Even as oil became increasingly important in the world economy, the delegates at the First World Power Conference transformed a vision of a renewable energy future into one of a general expansion of energy consumption as the basis of progress. In so doing, they downplayed the continued importance of fossil fuels and equated ‘conservation’ with the fullest possible use of all energy sources, renewable or not.

Redox flow batteries (RFBs) are a promising technology for grid-level energy storage. The ability to decouple energy and power, as well as the potential for low-cost and safe materials, make them particularly suited to this application. However, there is a lack of viable organic catholytes for RFBs and research thus far has primarily focussed on anolytes. Research in this thesis focuses on novel catholytes, degradation studies and electrolyte optimisation for aqueous organic redox flow batteries (AORFBs), the most challenging and yet the most promising area of this technology. In the first results chapter (Chapter 3), a series of triarylamines was synthesised. Initial electrochemical testing (using cyclic voltammetry) revealed one of these candidates, amino-functionalised 4-amino-trisphenyl amine, proved to be the most promising. However, battery cycling with this as the catholyte results in extensive polymerisation, leading to rapid capacity fade. This rapid capacity fade was improved by electrolyte optimisation, and utilising a mixed-salt system of 0.5 M HCl and 0.5 M H3PO4 it was possible to decrease capacity fade, increase coulombic efficiency and access more theoretical capacity. Chapter 4 explores commercially available phenothiazine dyes. Nicotinamide (NA) was used to increase solubility, specifically, the solubility of the most promising candidate explored, azure-a (AA), was doubled from 1 M to ca. 2 M. When cycled with NA in the supporting electrolyte, AA, had relatively stable cycling performance, though only half of the theoretical capacity was reached. Evidence suggests that this is the result of dimerisation of AA-based redox species. An extensive study using electrochemical impedance spectroscopy (EIS) showed that NA prevents a thick, charge-transfer blocking, film from forming on interphases in the cell (i.e. the electrode or membrane), thus improving the cycling performance. Chapter 5 further investigated both the dimerisation of AA-based species and their interaction with NA which leads to the observed improved performance. Through spectroscopic studies (NMR, EPR and UV/vis) it was found that there are at least four dimeric AA-based species in solution (most likely different dimer conformations). The role of pH on AA aggregation is also explored here for the first time. Finally, the origin of the improvement in battery performance using AA is shown to be preferential hydrogen-bonding with NA which intercepts AA aggregate, therefore reducing dimerisation and subsequent polymerisation. The final research chapter (Chapter 6) explores synthetic modification of phenothiazine, which is otherwise insoluble in aqueous conditions. A sulfonated propyl chain was found to improve solubility up to 1.15 M in 1 M HCl. However, upon cycling the sulfonate group was lost and an emulsion formed, leading to rapid capacity loss. This was improved by utilising NA as an additive (as shown previously in Chapters 4 and 5). Overall, this thesis has found that synthesising novel compounds presents many challenges, especially as the performance of candidate catholytes cannot be accurately predicted before experimental cycling. Ultimately the greatest improvements in cycling performance were achieved through electrolyte optimisation rather than synthetic changes in a particular catholyte family. It is therefore recommended to focus future research efforts on optimisation of the supporting electrolyte as the means for improving battery performance.

This dissertation is an investigation of the gendered dynamics of sustainable agriculture practiced by women operating commercial-scale, sustainable farms in Jaffna, Sri Lanka, with a focus on women's agency and freedoms within the agricultural sector. Women operate 26% of farms in Jaffna, yet women are notably absent from agricultural development policies. As climate change threatens the livelihoods and security of farmers in Jaffna, establishing data on the opportunities, barriers, and experiences of women as farmers is crucial for developing an accurate contextual understanding necessary to inform effective policies that ensure sustained food production and livelihood security. Using the capabilities approach as a conceptual framework and 50 individual interviews of with women farm operators in 2021, during COVID, this research examines the socio-cultural, economic, and policy-driven barriers that constrain women's agency and freedoms as primary farm operators. The study identifies a duality in women's experiences: while they demonstrate remarkable agency in sustainable agricultural practices within their farms, they face significant systemic barriers in engaging with external economic systems. A central insight of the research is the contrasting roles played by middle operators, who exploit women’s dependency to access external markets, and cooperatives, which serve as transformative bridges by fostering collective empowerment and expanding women's capabilities across both spheres. The study further highlights the innovative localized strategies women employ to adapt to climate vulnerabilities and systemic constraints. By blending traditional ecological knowledge with modern agricultural technologies, women have developed integrated farm management systems that optimize productivity, enhance biodiversity, and build resilience to environmental shocks. These findings challenge the conventional image of farmers as solely men battling nature and instead position women as central agents of ecological stewardship and sustainability.

Lowering emissions from power generating gas turbines, while retaining efficiency and power output, constitutes a formidable task, both at fundamental and technical levels. Combined gas turbine cycles involving air humidification are particularly attractive, since they provide additional power with improved efficiency. Water or steam addition promotes the reduction of nitrogen oxides emissions, for both the premixed and non-premixed modes of operation. Consequently, there is an urgent need for thorough understanding of the combustion chemistry and flow-chemistry interaction under high pressure and high humidity conditions as well as simulating the turbulent flow field with realistic chemistry. Both objectives require the development of reduced kinetic mechanisms. Reduced mechanisms for methane combustion valid for high pressure and high humidity are developed here, using the CSP (computational singular perturbation) method. The effects of humidity and pressure on the dynamics of NO formation pathways are discussed. A reaction progress variable model for the simulation of turbulent combustion is also developed, valid for adiabatic, non-adiabatic, premixed as well as partly or non-premixed combustion of various fuels, including natural gas, hydrogen and syngas. The model utilizes the CSP methodology for accurate mapping of the pertinent thermochemical data on a set of two reaction progress variables. Preliminary results are displayed.

We analysed the effect of applying Dutch thermal efficiency standards of residential dwellings, conversion efficiency, appliance fuel mixes and appliance ownership rates, to the UK residential sector. We found that although aggregate energy consumption does not change significantly, pollution emissions are reduced significantly. Thus, the primary difference between housing and appliance stocks in the two regions is in terms of fuel mixes. However, improved thermal efficiency does allow for increased dwelling warmth without increasing emissions. Adapting Dutch standards in the UK would lead to a one-time improvement of the environmental situation, after which the trend is continued.

The chemisorption and reactivity of SO2 on Pt{111} have been studied by HREELS, XPS, NEXAFS and temperature-programmed desorption. At 160 K SO2 adsorbs intact at high coverages, with η2 SO coordination to the surface. On annealing to 270 K, NEXAFS indicates the SO2 molecular plane essentially perpendicular to the surface. Preadsorbed Oa reacts with SO2 to yield adsorbed SO4, identified as the key surface species responsible for SO2-promoted catalytic alkane oxidation. Coadsorbed CO or propene efficiently reduce SO2 overlayers to deposit Sa, and the implications of this for catalytic systems are discussed.

The production of fuels and other value-added chemicals from sunlight is one of the proposed sustainable pathways to fulfil the constantly increasing energy demand while pushing towards a carbon-neutral circular economy. Photocatalytic (PC) and photo(electro)catalytic (PEC) systems, based on a semiconductor/liquid electrolyte junction, are capable of converting and storing the energy from the sun into chemical bonds. Over the years, poly(heptazine imide) ionic carbon nitride, a cheap, non-toxic, noble metal-free polymeric semiconductor has been exploited mainly as photocatalyst, and more recently, as photoelectrocatalyst. Although the performance of this material in PEC systems has been improving, its application is still hindered by low photocurrent response and poor long-term stability due to its notably high recombination rates, inefficient charge separation and transport, and consequent photo-degradation. Moreover, its compatibility with bio-based systems for green fuel and chemical production has been poorly exploited and rationalised. This thesis tackles these challenges by introducing a versatile and facile method to synthesise highly performant carbon nitride photoanodes, which can be interfaced with metal- and enzyme-based catalysts for CO2-reduction and hydrogen production with record photocurrents and stabilities. State-of-the-art cyanamide-functionalised poly(heptazine imide) (PHI) ionic carbon nitride (NCNCNx) electrodes were produced by co-deposition with indium tin oxide (ITO) nanoparticles, binding agents and conductive bridges, on a thin alumina-coated FTO glass substrate. The Al2O3|ITO:NCNCNx photoelectrodes displayed remarkably low onset potential and an outstanding 1.4 ± 0.2 mA cm–2 at 1.23 V vs the reversible hydrogen electrode (RHE) when selectively oxidising 4-methylbenzyl alcohol. Detailed spectroscopic studies shine a light on electron extraction kinetics within the photoanode and show that the addition of the ITO nanoparticles significantly improves the extraction of electrons from the carbon nitride, which otherwise remain trapped in the material, whilst the alumina underlayer reduces the electrical resistance between the ITO nanoparticles and the FTO substrate leading to record photocurrents. Furthermore, record stability of over 51 hours under continuous operation was achieved by systematically studying the effect of applied potential and light intensity on the ITO:NCNCNx photoanode long-term performance. Voltage-dependent spectroscopic analysis revealed irreversible changes in the carbon nitride morphology and electrochemical behaviour after applying any potential higher than 0.4 V vs RHE and low light intensity. Moreover, operating under concentrated solar light proved fundamental in ensuring high stability. To take advantage of the local temperature increase, the photoanode was coupled to a thermoelectric (TEG) unit, capable of converting the otherwise wasted heat into additional voltage, and employed in a TEG-PEC cell to drive glycerol oxidation coupled to CO2-to-CO reduction for over 70 hours under no external applied bias. As a proof of concept, the ITO:NCNCNx photoanode was also employed in an unassisted 2-electrode photoelectrochemical setup wired to a formate dehydrogenase (FDH) enzyme bio-cathode to perform selective CO2-to-formate conversion. Even under 1 sun, the bio-hybrid PEC system could withstand 10 hours of operation. Finally, the use of a [FeFe]-hydrogenase (H2-evolving enzyme) possessing a positive surface charge around the active site made it possible to directly interface it to the negatively charged cyanamide-modified graphitic carbon nitride (NCNCNx) as photocatalyst powder in solution, without the need for an electron mediator. In conclusion, this thesis showcases significant advancements in addressing the inherent challenges of poly(heptazine imide) ionic carbon nitride for photo(electro)catalytic applications. Through a systematic and fundamental approach, state-of-the-art photoanodes with record-breaking photocurrents and long-term stability were developed for the selective oxidation of organic waste-derived substrates. The integration of NCNCNx in PEC devices and a bio-hybrid PC system demonstrated its potential to drive un-assisted CO2 reduction to green fuels. By improving the efficiency, stability, and versatility of this promising carbon-based polymeric semiconductor, this thesis aims to serve as a platform for further research on – and application of - carbon nitride materials for photo(electro)catalytic and biohybrid systems.

Hybrid power plants consisting of a gas turbine and solid oxide fuel cells (SOFC) promise high electrical efficiencies if both components are directly coupled and the SOFC is operated at elevated pressure. This contribution discusses various aspects of the pressure influences on electrochemistry at the electrodes to operating strategies of a hybrid power plant. The influence of pressure on SOFC performance has been investigated theoretically and experimentally. Experiments are carried out using a test rig that allows for characterization of SOFC stacks at pressures up to 0.8 MPa. Performance curves and electrochemical impedance spectra are used for evaluations. In addition to experimental investigations an SOFC stack model is developed based on an existing electrochemistry modeling framework. The stack model is experimentally validated and used for a theoretical analysis of pressure. As expected, Nernst potential increases with increasing pressure causing a higher open circuit voltage. Furthermore, gas diffusion is enhanced with increasing pressure and the charge transfer reaction is facilitated due to higher adsorption rates of reactants at the electrode surfaces. At constant operating conditions and efficiency an increase in SOFC power density of up to 83% is measured. If power density is kept constant, electrochemical efficiency is improved by up to 14 %. Results generally show that pressure influence is stronger at low pressures up to 0.5 - 1 MPa and weakens towards higher pressures.  The influence of pressure on formation of nickel oxide and solid carbon is investigated. An analytical evaluation of the nickel oxidation propensity shows thatnickel oxidation is more likely to occur at higher pressures because the equilibrium partial pressure of oxygen in the anode gas increases. Carbon deposition is another degradation mechanism that can decrease the performance of an SOFC system. It was investigated via thermodynamic simulations using the software package Cantera. Thermodynamic equilibrium of gas mixtures with different oxygen to carbon ratios is calculated showing that the aptitude for carbon deposition is highly pressure dependent. Carbon deposition should be avoidable if oxygen to carbon ratio is kept above 2 within conditions that are relevant for hybrid power plants. The developed stack model is integrated into an existing validated gas turbine model that is extended to include further SOFC system components. A system operating strategy is presented that is based on a gas turbine control. Operating conditions of the SOFC are not directly controlled. A sensitivity analysis is carried out showing that the power ratio between gas turbine and SOFC is the most important parameter in order to achieve a high electrical efficiency. Other parameters like the number of SOFC stacks as well as gas and heat recirculation rates are of less importance. Thermal losses can significantly reduce electrical efficiency if they occur downstream of the recuperator. Finally, the operating range of a hybrid power plant based on the proposed system control is investigated. It is found that high electrical efficiencies above 60% (based on the HHV) are achievable within an electrical power range from 310 to 670 kW if gas turbine speed and SOFC electrical power are adjusted.