Design, thermodynamic, and economic analyses of a green hydrogen storage concept based on solid oxide electrolyzer/fuel cells and heliostat solar field

Abstract

Green hydrogen production is facing challenges in balancing economic feasibility with sustainability. Employing efficient hydrogen production designs and benefiting from the potential of hydrogen storage provide two promising strategies to mitigate the economic constraints associated with green hydrogen production. This paper proposes a novel hybrid design for green hydrogen production/utilization based on efficient high-temperature units, including heliostat solar field, solid oxide electrolyzer cell (SOEC), and solid oxide fuel cell (SOFC). The proposed system is comprehensively investigated from thermodynamic and economic perspectives, along with conducting a case study based on hourly electricity prices and actual solar data. The system demonstrates a hydrogen production rate of 7.76 ton/day using the SOEC and a power generation of 54.3 MWh in the SOFC for peak demand shaving, yielding an overall round trip efficiency of 74.2%. The case study results indicate that the economic feasibility is significantly compromised if all the produced hydrogen is sold at prices below 2.75 $/kg; while, implementation of hydrogen storage for peak shaving can yield a promising payback period of less than 2 years. The hydrogen and hourly electricity prices, along with the duration of peak times, are the other critical factors that affect economic viability.