The operational costs of thermal energy storage (TES) and compressed air energy storage (CAES) differ mainly based on capital expenditure (capex), maintenance, and overall system maturity.
Capital Expenditure (Capex) Comparison
- Thermal energy storage systems have a lower global average installed capex cost around $232/kWh.
- Compressed air energy storage systems are somewhat higher in capex, averaging about $293/kWh globally.
- For thermal energy storage, more detailed cost modeling provides a capex estimate of approximately $350/kWh with operational costs around 13.5 cents/kWh thermal energy at a 10% internal rate of return (IRR).
- TES capex values reported in some technical studies range broadly from $15.5 to $35.5 per kWh in different configurations, which may reflect system scale or technology variations.
Operation and Maintenance (O&M) Costs
- TES operation and maintenance costs arise from materials and operational activities, including fixed administrative costs and capacity-related maintenance such as molten salt freeze protection and tank upkeep.
- CAES operational costs are not specified in detail, but typically, CAES systems have mechanical components (compressors, turbines) that contribute to maintenance, potentially making O&M costs higher than TES’s relatively static storage components.
- Compared to batteries, both TES and CAES have lower degradation and longer lifespans, which can reduce maintenance frequency and costs over time.
Cost Drivers and Regional Differences
- China’s significant deployment of both TES and CAES technologies has driven down costs through scale and favorable policies, with lower capex and presumably optimized O&M costs in those markets.
- Outside China, TES and CAES capex can be 54% and 68% higher respectively, implying O&M costs might also be elevated in markets with less mature deployment.
Summary Comparison
| Aspect | Thermal Energy Storage (TES) | Compressed Air Energy Storage (CAES) |
|---|---|---|
| Average Global Capex | ~$232/kWh | ~$293/kWh |
| Capex Variation | $15.5–35.5/kWh (technical studies) | Higher than TES, mechanical complexity |
| Operational Costs | ~13.5 c/kWh thermal energy (IRR 10%) | Not explicitly reported, generally higher due to mechanical parts |
| Maintenance | Fixed admin + materials (e.g., molten salt freeze protection) | Maintenance on compressors, turbines, and pressure vessels |
| Regional Cost Differences | Lower in China, 54% higher elsewhere | Lower in China, 68% higher elsewhere |
In conclusion, operational costs for TES tend to be lower or more stable primarily because of fewer moving parts and simpler maintenance needs, whereas CAES has higher capex and potentially higher operational costs due to mechanical system requirements. Both storage types currently present cheaper options than lithium-ion batteries for long-duration storage beyond 8 hours.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-do-the-operational-costs-of-thermal-energy-storage-and-compressed-air-storage-compare/
