Cost analysis of alternative large-scale high-temperature solid oxide electrolysis hydrogen production facilities

We extend our past cost analysis of gigawatt-scale solid oxide electrolysis (SOE) facilities that produce high purity hydrogen gas from water by estimating construction and operating costs for three new alternative design cases: (1) offsite feed steam generation; (2) near-atmospheric pressure (NAP) stack; and (3) onsite electric boiler feed steam generation. Pressure effects on hydrogen electrode-(cathode-)supported SOE cell (SOEC) stack performance are estimated to determine facility-wide stack capital costs for achieving a fixed H-2 production at different pressures. Capital costs for modular balance of plant (BOP) process equipment are estimated for each new design case using our past equipment sizing, design, and cost data and scaling relationships. We update BOP equipment sizing and design for the NAP case using Aspen (R). Vendor quotes for electric boilers are used to estimate costs for electric boiler design cases. Factory and onsite assembly and installation costs for SOEC stacks and BOP equipment are calculated using our past first-principles approach. First-of-a-kind (FOAK) and N-th-of-a- kind (NOAK) production maturity costs are estimated for all cases. Use of NAP stacks offers the lowest facility total capital cost (TCC, similar to 23% lower than base) while use of small electric boilers requires the highest TCC (similar to 3% higher than base). H-2 production costs decrease from the base of similar to$2.17/kgH(2) to similar to$1.92/kgH(2) for 1 GW(e) DCSIP facilities utilizing NAP stacks supplied by offsites steam situated in large modules and blocks for $0.030/kWh(e) and $0.009/kWh(t) electricity and heat prices, respectively. We report all costs in 2021 US dollars.