System thermodynamics for solid oxide cell systems

Electricity, heat, and transport sectors are presently some of the largest emitters of greenhouse gases. To achieve climate neutrality, it is critical that these energy demands be met by renewable sources. Solar and wind power are the cheapest and fastest-growing means of harnessing renewable energy, but they are dependent on dynamic weather patterns. Building reliable energy systems based on renewables will require storage of energy over short and long timescales. In addition, many transport and industrial applications are not easily adaptable to directly use renewable electricity. Renewable electricity can be used to produce synthetic fuels called ‘E-fuels’. They have high energy density and chemical stability, making them suitable for long-duration energy storage and hard-to-electrify applications. E-fuels (primarily hydrogen) can be produced using electricity, and vice-versa, using devices such as solid oxide cells (SOC). The high operating temperature of SOCs brings unique advantages and system integration opportunities. This thesis aims to analyse and optimise SOC systems, particularly for energy storage and heavy transport applications. It brings in innovative thermodynamic concepts and highlights the ability of SOC systems to be a valuable part of a fully renewable energy system. How can chemical reactions involving e-fuels be carried out efficiently? What design choices can contribute to making SOC systems more efficient? Which e-fuels can be used by SOC systems most efficiently? Can fully renewable electricity systems be achieved at affordable costs? Can SOC systems and e-fuels power cruise ships for long distances? These are some of the questions addressed in this thesis.