Energies, Vol. 18, Pages 6604: Scheme Design and Performance Optimization for a 660 MW Ultra-Supercritical Coal Fired Unit Coupled with a Molten Salt Energy Storage System

Energies, Vol. 18, Pages 6604: Scheme Design and Performance Optimization for a 660 MW Ultra-Supercritical Coal Fired Unit Coupled with a Molten Salt Energy Storage System

Energies doi: 10.3390/en18246604

Authors:
Bin Zhang
Wei Su
Junbo Yang
Congyu Wang
Cuiping Ma
Luyun Wang
Xiaohan Ren

With the continuous increase in the proportion of renewable energy in the power grid, enhanced operational flexibility of the power system is required. As baseload generators, combined heat and power (CHP) units are prime candidates for flexibility retrofits that guarantee grid stability. Among the available options, molten-salt thermal energy storage (TES) offers an energetically efficient route to decouple heat and electricity production in CHP plants. In this study, a 660 MW ultra-supercritical coal-fired unit is taken as the object of investigation. Sixteen technical routes incorporating steam extraction and electric heating for thermal energy storage and discharging are systematically designed. Results demonstrate that all the combined schemes significantly improve the operational flexibility of the unit. Among them, the C1-S1 configuration exhibits the most outstanding overall economic performance, with a six-hour thermal storage capacity of 294.34 MWh. The system exergy destruction is measured at 6258 kW, while the round-trip efficiency and thermal efficiency are determined to be 81.11% and 45.48%, respectively.