Baseload Hydrogen Supply from an Off-grid Solar PV-Wind-Power-Battery-Water Electrolyzer Plant

Green hydrogen will play a key role in the transition to a carbon-neutral energy system. This study addresses the challenge of supplying baseload green hydrogen through an integrated off-grid alkaline water electrolyzer (AWE) plant, wind and solar photovoltaic (PV) power, a battery energy storage system (BESS), and a hydrogen storage system based on salt and rock cavern geologies. The capacities of the components and the hydrogen storage size are optimized simultaneously with the control of the AWE plant to minimize the levelized cost of hydrogen (LCOH2) of the gas supplied. The operation of the system is simulated over 30 years with a 15 min time resolution, considering degradation, operating expenses, and component replacements. Power generation data collected from a wind farm and a solar PV installation, both located in southeastern Finland, are used for system simulation. A sensitivity analysis, exploring different hydrogen demand rates, discount rates, and installation years, is conducted for both systems considering rock and salt caverns, providing the optimal configuration for each case. It is found that for the price scenario of the year 2025, for a combined 100 MW AWE and compressor, the optimal hydrogen demand rate is 12 kg/min with an LCOH2 of 3.14 e/kg and 2.77 e/kg in systems including rock and salt caverns, respectively.