The paper proposes a boiler-side molten-salt TES integration for a 350 MW CFPP that extracts main and reheat steam for heat transfer into high-temperature salt, using a scheme that mitigates risks like reheat overtemperature and turbine axial thrust imbalance compared to turbine-side concepts. A numerical model spanning turbine, heat exchangers, and tanks is developed, with sensitivity studies across design and off-design operation, including thermodynamics, economics, and CO2 reduction.
Minimum generation can be reduced to 16.31% of rated load; equivalent round-trip efficiency reaches 75.38–77.33% in design and 67.61–84.87% off-design; TES exergy efficiency is 77.48–81.38%. Under heat discharge, generation increases by 9.56% THA, expanding flexible operating range for system services.
With 212.21 MWh storage capacity, levelized cost of delivery is 135.35 USD/MWh and CO2 reductions are 59.58–66.16 tonnes depending on operating condition, indicating abatement potential during peak/valley shifting. By focusing on boiler-side integration, the concept addresses limitations of prior turbine-side or flue-gas approaches and offers an efficiency–feasibility balance for retrofit.
Why it matters
Boiler-side CFPP–TES coupling lowers technical minimums and time-shifts energy at competitive equivalent efficiencies, enabling greater wind/solar accommodation without CAES siting constraints or large compressor requirements typical of PTES. For asset owners, the reported LCOD and flexibility gains offer an actionable transition step while planning deeper repowering to clean heat or longer-duration storage.
The evidence supports Repower’s mission: repurposed coal sites can become clean, flexible assets that stabilize renewable-heavy grids while preserving jobs and grid connections. Well-designed TES integrations are valuable incremental milestones on the repowering pathway, accelerating emissions cuts with targeted investments that leverage existing assets.