The cost implications of integrating molten salt energy storage (TES) with existing power plants involve several factors related to capital expenditure (capex), operational costs, and the system’s design parameters.
Capital Costs and Cost Metrics
- Molten salt thermal energy storage typically has a capital cost around $350 per kWh thermal capacity, translating to approximately 13.5 cents per kWh thermal for a 10% internal rate of return (IRR). Lower costs in the range of 5-10 cents/kWh thermal may be achieved in favorable scenarios.
- According to cost models developed for two-tank molten salt sensible heat storage systems, the capital cost depends strongly on the power rating (maximum electrical power output) and the nameplate capacity (total thermal energy stored). Larger power ratings increase costs due to the need for larger or more robust heat exchangers and associated materials.
- Studies aiming to lower capital costs target $2–4 per watt or around $15/kWh thermal storage cost, which is considered achievable by optimizing storage temperatures and salt formulations. For example, operating the storage at a maximum allowable temperature for stainless steel tanks (~650°C) can help meet this cost goal, thanks to improved heat capacity and thermal stability of molten salts at these temperatures.
Operational and Integration Considerations
- Molten salt storage can deliver heat at roughly constant temperature and conditions, making it compatible with existing thermal power plants, including solar thermal and fossil fuel plants retrofitted for storage integration.
- Using molten salt as both the heat transfer fluid and storage medium simplifies integration and can produce a large temperature difference (~280 K), which maximizes energy storage capacity and efficiency.
- The molten salt thermal storage can be significantly less expensive than lithium-ion batteries when measured on an equivalent thermal or electric energy basis—up to 33 times cheaper in some cases—making it economically attractive for long-duration energy storage and smoothing power output of existing plants.
Summary of Cost Implications
| Aspect | Cost Range / Consideration |
|---|---|
| Capital expenditure (capex) | Approx. $350/kWh thermal; target $15/kWh thermal |
| Levelized cost of storage energy | 5-13.5 cents per kWh thermal |
| Comparison with batteries | Up to 33 times cheaper than lithium-ion batteries |
| Operating temperature | ~650°C for optimal cost and material stability |
| Integration complexity | Moderate; benefits from constant temperature output |
These cost factors imply that integrating molten salt energy storage with existing power plants involves significant upfront capital investment but offers low operational costs and competitive levelized costs of stored energy. The technology’s thermal nature aligns well with thermal power plants, facilitating relatively straightforward retrofits that enhance dispatchability and reduce fossil fuel backup needs, thereby improving economic and environmental outcomes.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-cost-implications-of-integrating-molten-salt-energy-storage-with-existing-power-plants/
