Minimizing the cost of hydrogen production through dynamic polymer electrolyte membrane electrolyzer operation

Abstract

Growing imbalances between electricity demand and supply from variable renewable energy sources (VREs) create increasingly large swings in electricity prices. Polymer electrolyte membrane (PEM) electrolyzers can help to buffer against these imbalances and minimize the levelized cost of hydrogen (LCOH) by ramping up production of hydrogen through high-current-density operation when low-cost electricity is abundant, and ramping down current density to operate efficiently when electricity prices are high. We introduce a technoeconomic model that optimizes current density profiles for dynamically operated electrolyzers, while accounting for the potential of increased degradation rates, to minimize LCOH for any given time-of-use (TOU) electricity pricing. This model is used to predict LCOH from different methods of operating a PEM electrolyzer for historical and projected electricity prices in California and Texas, which were chosen due to their high penetration of VREs. Results reveal that dynamic operation could enable reductions in LCOH ranging from 2% to 63% for historical 2020 pricing and 1% to 53% for projected 2030 pricing. Moreover, high-current-density operation above 2.5 A cm −2 is increasingly justified at electricity prices below $0.03 kWh −1 . These findings suggest an actionable means of lowering LCOH and guide PEM electrolyzer development toward devices that can operate efficiently at a range of current densities. • Dynamic operation reduces levelized cost of hydrogen by up to 63% for 2020 prices • Dynamic operation reduces hydrogen cost by up to 53% for projected 2030 prices • Operation above 2.5 A cm −2 is justified at electricity prices below $0.03 kWh −1 • Capital cost reduction of $601 from $898 kW −1 lowers hydrogen cost by 25% Electricity contributes most to the levelized cost of hydrogen (LCOH) from water electrolysis. Abundant low-cost electricity from variable renewable energy justifies operating electrolyzers at high current densities to increase H 2 production. Ginsberg et al. introduce a model to minimize LCOH by optimizing current density for any electricity pricing scheme.