A renewable energy storage concept integrating a solid oxide electrolyser and metal hydride compressor: Thermodynamic assessment

• Published in: International journal of hydrogen energy 2024-10
• Main Authors: Singh, Uday Raj, Bhogilla, Satyasekhar, Ravenkar, Shripad
• Format: Article
• Language: English
• Subjects: Energy and exergy analysis; Hydrogen storage; Metal hydride compressor; Solid oxide electrolyser; Thermodynamic analysis
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.09.324

Solid oxide electrolysis (SOE) achieves exceptional conversion efficiency by utilizing thermal energy to fulfil a portion of its energy requirements. Hence, it can be combined with alternative thermal energy sources to decrease the reliance on electrical power. The study presents an MH (metal hydride) compressor, which is used to compress the hydrogen produced from SOE. The integrated two-stage MH compressor incorporated in the present study efficiently raises H2 pressure to 350 bar. It is achieved by the utilization of a heat transfer fluid (HTF) at approximately 140 °C for heating and 20–40 °C for cooling. Energy and exergy analysis has been performed to examine the thermodynamic and electrochemical aspects of hydrogen production using an SOE. Moreover, the system's performance after the incorporation of the MH compression unit is also evaluated. The study has investigated how crucial operating parameters, such as operating temperature, current density, supply pressure, absorption and heat source temperature, effect the system's energy and exergy efficiency. It was observed that under specific operating conditions, the energy efficiency of SOE alone is approximately 60.57%. This efficiency increases to 66.5% when absorption heat from the MH unit and work of compression are incorporated. Conversely, the exergy efficiency of SOE was evaluated to be 68.69%, and it rises to 77.47% after considering compression work and absorption heat from the MH unit. •A SOE with two-stage MH compressor is proposed for renewable energy storage.•MH compression elevates energy efficiency from 60.57% to 66.5%.•V40Ti21.5Cr38.5 and V70Ti7Cr23 alloy pairs raise hydrogen pressure to 350 bar.•Effect of temperature and current density on overall performance is studied.•The exergy efficiency of integrated system increases from 68.69% to 77.47%.