Isobaric tanks system for carbon dioxide energy storage – The performance analysis

Abstract

The paper presents the results of thermodynamic and economic analysis of a compressed carbon dioxide energy storage installation using a novel solution, i.e. isobaric carbon dioxide tanks. The solution assumes the installation of low-pressure and high-pressure vessels in such a way that they are isobaric so that during the process of compression and expansion of gas there will be no need to use throttling valves to establish a constant level of pressure before the compressor and expander. The throttling valves using decrease the round-trip efficiency of the system by generating losses in the energy balance. The article presents the results of calculations of tank main geometry features also the pressure dependence of carbon dioxide in the high-pressure tank to the low-pressure tank. Thermal energy storage and a single-stage compressor and expander are considered in the energy storage system. A thermodynamic analysis was carried out to determine the basic parameters of the installation, such as the maximum round-trip efficiency of the energy storage system, which was 76% for 220 kPa in low pressure and 28.2 MPa in a high-pressure tank. The maximum temperature calculated at the compressor outlet was 612 °C. Levelized cost of storage was determined at the level of 593.87€/MWh.