Integrating Solar Energy, Desalination and Electrolysis

Solar electricity enables the advancement and deployment of technologies that are strongly influenced by clean energy availability and cost. The economics of both desalination and hydrogen production from water electrolysis are dominated by the cost of energy, and the availability of inexpensive solar energy creates markets and offers incentives to the desalination and electrolyzer industries to further advance their technologies. This study focuses on the production of high-purity water and hydrogen from seawater. Current electrolyzers require deionized water so they need to be coupled with desalination units. We show that such coupling is cost-effective in hydrogen generation, and it also offers benefits to thermal desalination, which can utilize waste heat from electrolysis. Furthermore, such coupling can be optimized when electrolyzers operate at high current density, using low-cost solar and/or wind electricity, as such operation increases both hydrogen production and heat generation. Results of techno-economic modeling of polymer electrolyte membrane (PEM) electrolyzers, define thresholds of electricity pricing, current density, and operating temperature that make clean electrolytic hydrogen cost-competitive with hydrogen from steam methane reforming (SMR). By using 2020 hourly electricity pricing in California and Texas, we estimate that hydrogen can be produced from seawater in coupled desalination-electrolyzer systems at prices near $2/kg H2, reaching cost parity with hydrogen produced from SMR. This article is protected by copyright. All rights reserved.