About the competitiveness of a thermal energy storage system as a way of setting up the NPP load following modee

Abstract

The article estimates the competitiveness of the thermal energy storage system (TESS) based on a high-temperature coolant (HTC) used as part of a VVER-based NPP unit. Some ways of improving the TESS competitiveness are considered. A few storage system versions differing in the equivalent process circuit of the regenerative heaters of the regular steam-turbine plant are presented. The direct electric energy storage systems based on using a Liquid Metal Battery (LMB) with solid-state inverters as DC/AC converters are considered as an alternative technology. The specific expenditures per unit power ($US/kW) and per unit capacity ($US/kWh) of the system serve as quantitative criteria. It is shown that the LMB-systems in combination with inverters are close to or outperform the existing versions of TESS in terms of the above-mentioned criteria provided that their declared characteristics are confirmed. Possible ways to improve the specific TESS indicators are described, in particular, the use of inert fillers and utilization of the steam-turbine plant boosting capacities, and optimization of the HTC temperature parameters. The expenditures for the equipment (with varying its technical characteristics) were evaluated using the Cost Estimating approaches, techniques widely used for feasibility studies in substantiating the implementation of Generation IV NPP designs. It is shown that, by implementing the considered ways of improving the NPP TESS, the system specific indicators can be improved approximately by a factor of 2 in capacity and by about 30% in power. The optimization of temperatures gives an additional gain of around 5% in expenditures per unit capacity. The possibility of such a significant improvement of TESS characteristics by using relatively simple methods gives the thermal storage technology a chance to preserve its place in the modern designs of NPP units.