Commercialization of photoelectrochemical cells for solar hydrogen production from water is challenging due to the competitive low cost of hydrogen derived from natural gas. Renewable (solar-derived) hydrogen from alternative sources with more favorable economics is therefore being explored. Currently, caustic scrubbers for H2S abatement from sour gas and wastewater produce NaHS, a hazardous commodity chemical that is produced in the Kraft process, to produce wood pulp from wood for the production of paper, tissues, cardboard, and similar end products. However, due to large transport distances between H2S sources and paper mills, oversupply of NaHS, or impurities in the NaHS, there are many scrubbers that produce a large excess of waste NaHS. To address this economic pain point, we have invented a regenerator system that uses a photoelectrochemical cell to split NaHS, producing saleable high-value commodity sulfur and renewably-derived hydrogen gas, while regenerating the NaOH so that it can be re-used for H2S adsorption. Our photoelectrochemical regeneration system uses sunlight to produce hydrogen from waste H2S using less than a third the energy that is required for H2O splitting, while simultaneously removing a hazardous caustic waste stream from the environment. For this project, we will build a proof-of-concept regenerator system that can be integrated into a regenerative scrubber prototype. This will accomplish three goals: Production of renewable hydrogen potentially using 1/3rd the energy of water splitting; Reduce the need for caustic scrubbers to continue to buy NaOH by regenerating it from NaHS; Eliminate waste NaHS economically by turning it into hydrogen fuel and non-hazardous sulfur. Intellectual property will be developed, and an analysis of end-user pain points and product-market fit will be accomplished by combining data from customer interviews, technical reports, and economic forecasts.
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