Energy Storage Analysis of A Hot-Dry-Rock Compressed Air Energy Storage (hdr-Caes) System

During the discharging process of compressed Air Energy Storage (CAES), fossil fuel is required and there is the problem of carbon-dioxide emissions. It may be resolved when hot dry rock is used as the storage place for compressed air. Hot-Dry-Rock Compressed Air Energy Storage (HDR-CAES) system is proposed and the thermodynamic cycle of HDR-CAES is constructed in this paper. The energy storage and power generation performances of HDR-CAES system are studied. Under different working conditions (compressed air flow rate and compression pressure), the electricity consumption in valley power time, power generation in peak power time, and the round-trip efficiency are analyzed. Results indicate that the valley electricity consumption, power generation and round-trip efficiency of the system all fluctuates cyclically due to the influence of the ambient temperature. The valley electricity consumption and daytime power generation increase with the increase of compressed air flow rate and compressor pressure ratio. The round-trip efficiency of the system increases with the increase of compressor pressure ratio and the decrease of recharge air flow. For a long time operation of this system, power generation drops year by year, and the drop range is proportional to the compressed air flow rate and inversely proportional to the compression pressure; the fluctuation range of round-trip efficiency decreases with the increase of compression pressure and increases with the increase of air flow rate.