Designing off-grid green hydrogen plants using dynamic polymer electrolyte membrane electrolyzers to minimize the hydrogen production cost
Michael Ginsberg, Daniel V. Esposito, Vasilis Fthenakis
Abstract
Hydrogen produced from electrolysis is an attractive carbon-free fuel and feedstock, but potential benefits depend on the carbon intensity of electricity production. This study uses technoeconomic modeling to analyze the benefits of producing zero-carbon hydrogen through dynamically operated polymer electrolyte membrane electrolyzers connected to photovoltaic and wind variable renewable energy (VRE) sources. Dynamic operation is considered for current densities between 0 and 6 A cm−2 and compared to a constant current density of 2 A cm−2 for different combinations of VRE to electrolysis (VRE:E) capacity ratios and compositions of photovoltaic and wind energy in four locations across the United States. For optimal VRE:E and wind:photovoltaic capacity ratios, dynamic operation is found to reduce the levelized cost of hydrogen by 5%–9%, while increasing hydrogen production by 134%–173%, and decreasing excess electrical power by 82%–95%. The framework herein may be used to determine the optimal VRE:E capacity and VRE mix for dynamically operated green hydrogen systems.