Volume 55

Plant-level performance of a reversible solid oxide cell-based stack with H2-H2O-O2 and H2-H2O-Air system for a renewable energy-based microgrid Adil Muhammed, Sreenivas Jayanti

Abstract

Reversible solid oxide cells (ReSOCs) stack consume electrical energy to produce chemical fuel in the electrolyser (SOEC) mode of operation and convert stored fuel into electrical energy during the fuel cell (SOFC) mode of operation. On the whole, the stack operation is endothermic in the SOEC mode and exothermic in the SOFC mode. A mutually compatible balance-of-the-plant (BoP) with thermal integration for the dual mode of operation is necessary for the ReSOC stack. A detailed process model of ReSOC of MWe scale capacity is developed with two layouts for the BoP: an oxygen-based system and an air-based system. Auxiliary power generation in both modes improves the efficiency of the system. Plant-level compatibility shows the plant can be operated at a 1:2.5 charging-to-discharging time ratio, thus making it highly suitable for islanded power operation of the daily residential energy requirement driven primarily by a solar PV-based renewable energy system. In terms of overall performance, the oxygen-based system shows a roundtrip efficiency of around 70% compared to around 55% for the air-based system. This difference may be attributed to air compression in both modes which requires significantly higher parasitic power consumption.

Keywords Reversible solid oxide cell, renewable energy storage, balance-of-the-plant, fuel cell, electrolyser