Nov 2024
Zoom link: https://kaust.zoom.us/j/99234984956
Abstract
The transition from renewable energy to synthetic fuels, known as E-fuels, represents a pivotal strategy for achieving carbon neutrality and energy sustainability. Among the various renewables to E-fuel pathways, electrochemical CO2 conversion and green hydrogen production via water electrolysis stand out as promising due to their great potential. However, significant technical challenges need to be addressed to make the process more efficient. For the electrochemical CO2 conversion, upstream CO2 capture requires extensive purification and concentration process, increasing the overall operational costs. In addition, the downstream separation of products from the complex mixture is energy-intensive and costly, reducing the overall efficiency and economic viability of the system. More than that, electrocatalysts often face issues with low current density due to low CO2 solubility and competition from side reactions. For green hydrogen production, challenges include an incomplete understanding of the hydrogen evolution reaction (HER) mechanism and difficulties in scaling electrolyzers from lab to pilot scale. In this dissertation, we addressed these issues via system design, exploring electrocatalyst mechanisms and analyzing the performance with kilowatt-scale electrolyzer. Specifically, (1) we integrated glucose fermentation with CO2 reduction reactions (CO2RR) to ethanol, cutting 17.8% cost according to the technical-economic assessments (TEA). (2) We pressurized the CO2 to enhance the formate selectivity, leading to a significant increase in the current density. To advance green hydrogen production, (3) we utilized tungsten diselenide (WSe2) as electrocatalyst synthesized by chemical vapor deposition (CVD) to reveal the mechanism of defect engineering. (4) Finally, we evaluated the performance of a kilowatt-scale proton exchange membrane (PEM) electrolyzer, using experiments and modeling to analyze the effects of temperature on system performance. The findings presented in this dissertation highlight the potential of innovative system designs and advanced materials in overcoming existing barriers to E-fuel production technologies, paving the way for more efficient and scalable solutions.