Techno-Economic Assessment of Sustainable H₂ Production and Hydrogenation of Chemicals in a Coupled Photoelectrochemical Device

Photoelectrochemical (PEC) water splitting has been proposed as a promising method to generate sustainable hydrogen, but its competitiveness is hindered by the relatively high cost compared to other generation methods. One strategy to increase the competitiveness of PEC-generated H₂ is coupling water splitting with hydrogenation reactions that produce higher-value chemicals. However, the optimal coupled reaction and the energetic and economic benefits of the coupled concept remain uncertain, especially on larger scales. Here, we conduct a comprehensive techno-economic assessment (TEA) of a hypothetical PEC plant with a 1,000 kg H₂/day capacity, considering seven potential hydrogenation reactions. The TEA results show that the coupling hydrogenation reaction significantly improves the economic metrics of the system, with acetophenone (ACP) to 1-phenyl ethanol offering the highest returns. Sensitivity analysis shows that solar-to-H₂ efficiency and H₂-to-chemicals conversion efficiency are the most critical parameters affecting the levelized cost of hydrogen (LCOH) of the system. Finally, benchmark conversions that would result in competitive LCOH values that are comparable to that of fossil fuel based H₂ are identified, and the potential impact of these coupled PEC hydrogenation reactions on the global H₂ market is discussed. © 2024 American Chemical Society.