Economic assessment of hydrogen production from solar driven high-temperature steam electrolysis process

A key prerequisite for the hydrogen economy is cost-effective renewable hydrogen supply. This paper provides a framework for the thermodynamic and economic assessment of solar hydrogen production from the high-temperature steam electrolysis (HTSE) route. A system configuration for the solar-driven steam electrolysis plant is proposed. The thermodynamic and economic analysis is done for varying temperature and current density conditions of the solid oxide electrolyzer powered by concentrated solar (CSP) and photovoltaic (PV) power plants. Based on the expected reductions in the cost of plant components, the levelized cost of hydrogen (LCOH2) for the 2030 scenario is evaluated. Conditions for the viability of this route are checked by comparing the results with the polymer electrolyte membrane electrolysis (PEME) process. The optimum energy efficiency of a PV driven process increases from 9.1% at 873 K, 1500 A/m(2) to 12.1% at 1273 K. 8000 A/m(2). For the electrolyzer operating at 873 K, the optimum LCOH2 of 22 $/kg is obtained at 6000 A/m(2). For the electrolyzer temperature of 1073 K, LCOH2 drops from 16 $/kg at 5000 A/m(2) to 12.1 $/kg at 10000 A/m(2). When compared to PEME, this route becomes viable beyond 973 K, 6000 A/m(2) for PV and 923 K, 3000 A/m(2) for CSP driven processes. With the current state of economics, this process is not competitive with the industrial steam methane reforming route. However, the cost target of 6-8 $/kg is achievable if the component costs reduce to 2030 level. Thus, the process has potential to be commercially viable and should be pursued further by creating prototype and pilot scale demonstrations. (C) 2018 Elsevier Ltd. All rights reserved.