Dynamic characteristics and economic analysis of a coal-fired power plant integrated with molten salt thermal energy storage for improving peaking capacity.

Improving the peaking capacity of coal-fired units is imperative to ensure the stability of the power grid, thus facilitating the grid integration and popularization of large-scale renewable energy. To address this issue, this paper introduces a new concept that combines molten salt energy storage with coal-fired power plants. The proposed design consists of extracting a portion of steam from the turbine side and adjusting the extracted steam mass flow rate by adjusting the valve opening to improve the dynamic characteristics of a coal-fired power plant in terms of both increasing the peaking depth and peaking speed. A coal-fired boiler with integrated thermal energy storage was dynamically modeled using Dymola and its accuracy was verified. The results show that the highest equivalent round-trip efficiency is achieved by extracting from the main steam and discharging into the feedwater during charging process and from reheater1 and discharging into the feedwater during discharging process; The peaking potential during charging and discharging is 12.83 % P e and 6.86 % P e respectively, with maximum peaking rates of 9.27 % P e /min and 5.11 % P e /min respectively, and the optimal peaking method is also proposed according to the different peaking situations. The total cost of equipment and materials to retrofit the conventional coal-fired units was 19,948,193 USD and the levelized cost of delivery was 151.29 USD/MWh. • Coal-fired power plant systems incorporating molten salt energy storage. • Dynamic characteristics and economic analysis of coal-fired power plants. • A peaking potential of 12.83 % P e during charging process and 6.86 % P e during discharging process. • A theoretical maximum peaking rate of 9.27 % P e /min during charging process and 5.11 % P e /min during discharging process. • LCOD is determined to be 151.29 USD/MWh. [ABSTRACT FROM AUTHOR]