Energy Analysis of Power-to-Power System Using Aqueous Methanol as Energy Carriers

Methanol is a good energy carrier for power storage, and large-scale storage and release of electric energy can be realized through integrated hydrogen production from water electrolysis, CO2 hydrogenation to methanol, hydrogen production from methanol reforming, and hydrogen fuel cells. In this paper, the methanol-based electric power storage and release is modeled and the power–power conversion efficiency is improved by heat transfer network optimization. The results show that the power-to-power (P2P) storage process can be realized by relying on a methanol aqueous solution under the condition of only power input. The heat exchange network can fully utilize the waste heat to realize the heating demand of the system, and the combustion of the purge gas from the methanol synthesis and part of the hydrogen at the outlet of SOFC is the key to balance the heat demand. Reducing the waste heat of the system can significantly improve the P2P energy efficiency, and the optimal conditions can obtain P2P energy efficiency of about 30%.