Photovoltaics, Solar Energy, Desalination, Electrolysis, Cogeneration
Summary / Abstract:
The economics of both desalination and hydrogen production from water electrolysis are dominated by the cost of energy, so widespread availability of inexpensive solar energy incentivizes the desalination and electrolyzer industries to further advance their technologies. This study focuses on the coupling of the production of potable water, deionized water and hydrogen gas from seawater. We show that such coupling is cost-effective not only for hydrogen generation, but also for desalination, as desalination can use waste heat from electrolysis. Additionally, such coupling can be optimized when electrolyzers operate at high current density, using low-cost solar and/or wind electricity, as high density operation increases both hydrogen production and heat generation. Results of techno-economic analysis define thresholds of electricity pricing, current density, and operating temperature that make “green” electrolytic hydrogen cost-competitive with hydrogen from steam methane reforming. By using historical and projected hourly electricity prices in the US-southwest, we estimate that hydrogen can be produced from seawater in desalinationelectrolyzer systems at prices near $2/kg H2, achieving cost parity with currently produced hydrogen. In addition, thermal energy for desalination could be supplied by the electrolyzer, creating a closed loop for continuous green H2 production.