Improving the performance and economics of reversible solid oxide cell-based hydrogen energy storage systems through the utilization of renewable alternative fuels

Reversible solid oxide cells (RSOCs) represent a promising solution for addressing the future challenge of large-scale renewable energy storage. However, the performance and economic viability of current RSOC systems are hindered by the large overpotential losses in electrolysis and apparent fuel (H₂) costs associated with power generation. This study employs a comprehensive numerical modeling approach to analyze the potential of renewable fuel (glycerol) in assisting hydrogen production performance and reducing operating costs within RSOC systems. The detailed comparative analyses and parametric studies are conducted on H₂-based and glycerol-based RSOC systems at typical operating conditions. Notably, it is found that the economic viability of hydrogen-based RSOC systems is hindered by the remarkable fuel (H₂) costs during nighttime despite of the favorable effects of larger stack capacity and higher temperature. While incorporating glycerol as an alternative fuel in RSOC systems offers significant advantages, including doubling the electrolytic H₂ production (from 585.92 Nm³·h⁻¹ to 1191.24 Nm³·h⁻¹) at a relatively low cost and substantially reducing the fuel expenses (from 594.30 $·h⁻¹ to 30.57 $·h⁻¹) for nighttime power generation, thus leading to competitive electrolytic hydrogen production cost (2.982 $·kg⁻¹) and noteworthy enhancement in economic viability (LCOE of 0.090 $·kWh⁻¹ and 0.304 $·kWh⁻¹ for electrolysis and power generation, respectively). The findings of this study provide valuable insights that contribute to the advancement of RSOC systems, thus facilitating the development of efficient, cost-effective, and sustainable energy storage and conversion technologies.