Realizing hybrid electrical and thermal energy storage by integrating an iron-air redox battery into the CSP-CaL system

The development of renewable energy through energy storage technologies has addressed the issue of energy fluctuations. However, the insufficient absorption capacity of the grid leads to significant power curtailment. In this work, a solid oxide iron-air redox battery (SOIARB) is integrated into the concentrated solar power (CSP) with calcium looping (CaL) system to achieve hybrid electrical and thermal energy storage. Among three integration scenarios, scenario-1 (CaCO₃ stream heats Fe stream) exhibits the highest round-trip efficiency (RTE). As the current density escalates from 100 A/m² to 2000 A/m², the energy efficiency of the battery decreases from 91.99 % to 53.60 %. Energy analysis shows that the CSP-CaL-SOIARB system performs best when the iron flow is 15.01 kg/s and the cross-sectional area is 74554.44 m². RTE of the overall system and SOIARB subsystem reach 48.77 % and 61.01 %, respectively. The integration of iron-air batteries has improved the power supply capacity of the overall system by 31.37 MW, an increase of 72.55 %. Exergy analysis shows that the exergy efficiency of the overall system reaches 50.04 %, which exhibits considerable potential in hybrid electrical and thermal energy storage.