Advanced Compressed Air Energy Storage (CAES) systems improve efficiency by capturing and reusing the heat generated during the air compression phase. This process, known as heat recovery, typically involves the use of heat exchangers that capture the heat from compressed air and store or transfer it to preheat the air before it expands through turbines during electricity generation.
How Heat Recovery Works in Advanced CAES:
- Heat Capture During Compression: When air is compressed, it heats up significantly. Instead of wasting this heat, advanced CAES systems use heat exchangers to absorb this thermal energy.
- Storage or Direct Use of Captured Heat: The recovered heat can either be stored temporarily in thermal energy storage systems or transferred immediately. This prevents the need for external fuel-based heating, which is common in traditional CAES systems where natural gas is burned to reheat air before expansion.
- Preheating Air Before Expansion: Before the compressed air is expanded in turbines to generate electricity, the stored heat is reinjected to warm the air. This preheating avoids large temperature drops that reduce turbine efficiency and energy output.
- Efficiency Gains: This heat recovery process can recover up to about 70% or more of the compression heat, which significantly reduces fuel consumption and increases overall system efficiency. Near-isothermal or isothermal compression and expansion processes, where temperature changes are minimized by effective heat exchange with a thermal mass, can yield isothermal efficiencies of 90–95%, approaching near-thermodynamic reversibility.
- Thermal Management Techniques: Advanced CAES uses sophisticated thermal management, including heat-absorbing and releasing structures (HARS) such as finned surfaces or sprays, external cooling circuits, and thermal storage materials. These maintain air temperature close to constant during compression and expansion, substantially reducing energy losses.
Summary of Benefits of Heat Recovery in Advanced CAES:
| Benefit | Description |
|---|---|
| Improved Efficiency | Recovers compression heat to preheat air, reducing fuel use and boosting energy output. |
| Reduced Emissions | Eliminates or lowers the need for combustion-based reheating, cutting greenhouse gas emissions. |
| Enhanced Reliability | Makes the energy storage cycle closer to ideal thermodynamic processes (near-isothermal). |
| Economic Advantages | Enables lower operational costs by maximizing energy reuse, despite higher initial capital costs. |
In essence, heat recovery in advanced CAES is a critical technology that captures and reutilizes the heat generated during compression, storing or directly using it to preheat air for expansion turbines, thereby enhancing overall energy efficiency and reducing environmental impact compared to conventional CAES systems.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-heat-recovery-work-in-advanced-caes-systems/
