Concept study of compressed CO₂ energy storage system integrated with nuclear power plants for flexible operation

Abstract

According to the 3020 Korean energy policy and the UN World Climate Convention, the proportion of renewable energy is expected to increase domestically and internationally. As the share of renewable energy increases, the problem of renewable energy intermittency emerges and has to be resolved for the sake of grid stability. To resolve this problem, the necessity of a nuclear power plant (NPP)'s load-following capability is expected to be increasing. To effectively operate nuclear power plant flexibly, an integration concept of the energy storage system (ESS) with the steam cycle of the pressurized water reactor’s secondary system is suggested in the thesis. Among many ESSs, utilizing a compressed carbon dioxide energy storage system (CCES) is suggested due to its advantages of having high round-trip efficiency (RTE), good possibility of realizing large capacity and power. Therefore, the feasibility of integration between NPP and CCES is investigated in this thesis through quantitative evaluation criteria. The pressurized water reactor (PWR) steam cycle analysis was conducted first. Based on the analysis, a CCES was designed and analyzed to obtain RTE of 64% and energy density of 3.8 kWh//m³. In order to further improve the energy density, a liquefied carbon dioxide energy storage system (LCES) is suggested by adopting idea from a liquefied air energy storage system (LAES). The LCES was designed and analyzed to have RTE of 46% and energy density of 36 kWh//m³.