The efficiency of thermal energy storage (TES) systems significantly influences their cost, as it impacts both the capital expenditure (capex) and operational costs. Here’s how efficiency affects the economics of TES systems:
Efficiency and Cost Elements
- Efficiency and Energy Losses: TES systems with higher efficiency tend to lose less energy during storage and release cycles. For example, a well-insulated thermal energy storage system might lose only 1-2% of its stored heat over 24 hours. Lower energy losses mean less purchased energy is wasted, reducing operational costs.
- Capital Costs (Capex): Efficient TES systems often require less storage material and infrastructure to achieve the same output. For instance, using particle storage media in a single silo instead of dual tanks can halve containment costs. Efficient systems might also be able to utilize lower-cost materials or simpler designs, further reducing capex.
- Operating Costs (Opex) and Electricity Prices: Efficient systems can optimize their energy use by absorbing excess renewable energy during low-demand periods and releasing it when needed, thereby leveraging low electricity prices. This strategy helps manage operational costs effectively.
- Scalability and Economies of Scale: More efficient systems can scale up with lower additional costs per unit of energy stored. Economies of scale can further reduce the overall cost per kWh-thermal as the system size increases.
Cost Savings with Efficient TES
- Monthly Savings: Efficient TES systems can provide significant cost savings, often between 30% and 150% monthly compared to traditional process heat, depending on the region.
- Cost per kWh: The cost of TES can be significantly lower than other forms of energy storage. For example, costs are estimated at around 13.5 c/kWh-thermal for a 10% IRR, though they can be as low as 5-10 c/kWh-thermal with reduced capex costs. Particle TES systems may achieve costs around $2/kWh-thermal.
Conclusion
The efficiency of thermal energy storage systems directly impacts their cost by minimizing losses, reducing capex requirements, optimizing electricity costs, and improving scalability. As technology advances, the cost-effectiveness of TES is expected to increase, making it a more viable option for integrating renewable energy sources into the grid.
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