Technoeconomic Analysis of Photoelectrochemical Hydrogen Production from Desalination Waste Brine Using Concentrated Solar Flux

Co-generation of hydrogen with value-added by-products is a promising route for affordable low-carbon hydrogen. This work presents a system for and a technoeconomic analysis of hydrogen with the co-generation of chlorine and sodium hydroxide from waste brine. The system uses a conceptual triple-junction gallium arsenide (3-J GaAs)-based photoelectrochemical (PEC) reactor at high solar concentrations (50–500x). The base case of 200x solar concentration results in a solar-to-chemical (SCE) efficiency of 15% and a levelized cost of hydrogen (LCOH) production of $15.76/kgH2. Revenue from by-products ($45.36/kgH2) is critical for offsetting the operating costs, with sodium hydroxide constituting 64% of total by-product revenue. The sensitivity analysis showed that under favorable combinations of the key variables (sodium hydroxide price, waste brine pretreatment price, and PEC replacement lifetime) PEC hydrogen generation from waste brine would be viable and have prices reaching $0.78/kgH2.