Optimal Dispatch of a Coal-Fired Power Plant with Integrated Thermal Energy Storage

As the share of intermittent renewable electricity generation increases, the remaining fleet of conventional power plants will have to operate with higher flexibility. One of the methods to increase power plant flexibility is to integrate a thermal energy storage (TES) into the water-steam cycle of the plant. TES can provide flexibility and achieve profits by engaging in energy arbitrage on the spot markets and by providing additional power on the control power markets. This paper considers a reference coal-fired power plant with an integrated TES system for the year 2019 in Germany. Optimal dispatch for profit maximisation with TES is simulated on the hourly day-ahead and quarter-hourly continuous intraday markets as well as on the markets for primary (PRL) and secondary (SRL) control power. Analysing the effects of TES round-trip efficiency and storage capacity on dispatch and the profits, I find that smaller TES systems with up to one hour of storage capacity can achieve substantial profits on the PRL market while also realising profits from energy arbitrage on the continuous intraday market. Higher TES round-trip efficiencies can help TES achieve significant profits also on the day-ahead market. The analysis shows that a storage capacity of 2–3 hours is enough to realise most of the energy arbitrage potential, while larger storage capacities can greatly increase TES profits on the SRL market. Small TES systems are found to increase the full load hours of the plant marginally. However, the increase becomes significant with larger storage capacities and can lead to higher CO 2 emissions for the individual plant.