Thermo-economic analysis of the integrated system of thermal power plant and liquid air energy storage

Abstract

In the context of the rapid development of renewable energy, load regulation of the power grid has become a vital issue, and many researches on load regulation by thermal power plants (TPP) have been conducted. As a promising large-scale energy storage technology, the liquid air energy storage (LAES) system has significant advantages such as clean, low investment cost, and no geographical restrictions. In this paper, a coupled system combined by TPP and LAES system (TPP-LAES) is proposed, and technical and economic analysis are carried out to obtain the best configuration of the integrated system and verify its economic benefits. Technical analysis results demonstrate that the maximum round trip efficiency (RTE) of the LAES subsystem can reach 93.74 % when the extraction pressure is 242.00 bar. The RTE of the LAES subsystem of the optimal configuration is 58.31 %, at which the extraction pressure is 8.55 bar. The comprehensive efficiency of the optimal TPP-LAES integrated system is 40.86 %, which is about 1 % higher than the standalone LAES system. The energy storage density is 95.80 kWh/m3, and the net output power is 79.30 MW, exhibiting excellent system performance. The economic analysis results reveal that the initial investment cost of the TPP-LAES integrated system is 67.17 % of that of the standalone LAES system, and the levelized cost of storage (LCOS) is 154.30 USD/MWh, 24.63 % lower than that of the standalone LAES system, with outstanding economic benefits.