Investigation of a novel high temperature solid oxide electrolyzer for solar hydrogen production

Abstract

This thesis proposes and investigates a new generation of photoelectrochemical cells for solar hydrogen production based on high temperature Solid Oxide Electrolysis Cells. Therefore, a set of experiments are designed to develop and select the most promising materials and configurations. Furthermore, the study includes a design of a novel testing station built to accommodate the various parameters to be tested in order to assess the performance of the proposed Photoelectrochemical Solid Oxide Cell (PSOC). As part of the design process, a material survey was conducted to screen potential semiconductors that are capable of operating at high temperatures. Subsequently, promising materials are selected and applied through specific chemical processes which can provide the required structure and surface properties. The material processing strategies to develop a light absorbing surface are made on commercial button cells; which has been tested and its performance is well-characterized under different operating conditions. Thus, improvements brought about by the developed photoactive layer can be detected under different types of light. The research further includes the thermodynamic and electrochemical modeling of a Solid Oxide Electrolysis Cell (SOEC). In this regard, the energy and exergy aspects of a single cell performance, as well as the performance of Solid Oxide Electrolysis (SOE) stack, are investigated. The exergoeconomic aspects of utilizing SOE plant at a large-scale is also considered through a detailed exergoeconomic analysis. Last, the models are used to examine the SOE performance sensitivity to variation in operating parameters and conduct an exergetic optimization to highlight the trade-offs between economic and technical performance optimums. In addition, the integration of SOE in solar tower power plant for hydrogen production is examined considering continuous operating by using thermal energy storage and a high efficiency supercritical carbon dioxide (S-CO2) power cycle. The findings of this thesis are expected to make a new solar hydrogen production pathway that is efficient, environmentally friendly, and in near-future expected to be economically competitive.