Performance Improvement of a Micro Gas Turbine Adopting Exhaust Gas Recirculation for CO2 Capture by Integration With Liquid Air Energy Storage

Abstract

Exhaust gas recirculation (EGR) can be applied to a micro gas turbine (MGT) for the efficient removal of CO2 using post-combustion capture. The EGR increases the CO2 concentration of the exhaust gas for the capture process, which augments the capture rate. However, the performance penalty of the MGTs caused by the rise in the compressor inlet temperature due to the EGR is a drawback. In this research, we investigated the integration of an MGT, adopting EGR with liquid air energy storage (LAES), an emerging energy storage technology. LAES stores electric energy from renewables or the power grid in the form of cryogenic liquid air. The liquefied air is pressurized and regasified to generate electricity during peak demand hours. In our proposed system, a portion of the cryogenic air is injected into the MGT’s compressor inlet. The purpose of the injection is twofold. Firstly, it decreases the compressor inlet air temperature, which enhances the MGT performance, especially the power output. Secondly, it increases the carbon dioxide composition of the exhaust gas, which enhances the carbon capture performance. An MGT system, equipped with a post-combustion capture and integrated with the cryogenic air injection, was analyzed. The analysis shows that the system power, system efficiency, and CO2 capture rate were improved, with the heat duty of the carbon capture process reduced in accordance with the increase in cryogenic flow rate, as expected. Moreover, the heat duty of the carbon capture process decreased significantly due to the increase in temperature and O2 concentration in the cryogenic air.