Designing off-grid green hydrogen plants using dynamic polymer electrolyte membrane electrolyzers to minimize the hydrogen production cost

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.