The efficiency of Compressed Air Energy Storage (CAES) systems typically ranges from about 60% to 80%, depending on the specific design and operational conditions. More detailed assessments indicate that the round-trip efficiency — the ratio of energy output to input after compressing, storing, and expanding air — is often between 60% and 65% for many CAES plants, with some simulations showing efficiencies around 70% to 71%.
In contrast, lithium-ion battery systems exhibit significantly higher round-trip efficiencies, often in the high 80% range, with some estimates going into the low 90% territory depending on the battery chemistry and system design. For example, lithium-ion batteries typically achieve efficiencies around 85% to 90%, meaning less energy is lost in charging and discharging cycles compared to CAES.
The lower efficiency of CAES largely stems from thermodynamic losses during air compression and expansion. When air is compressed, it heats up and often this heat is lost to the environment instead of being recovered and reused. Conversely, air cools during expansion, which can reduce electricity output. To mitigate this, CAES plants often use natural gas to reheat the air before expansion, but this reduces the system’s renewability and overall efficiency.
In summary, lithium-ion battery storage is generally more efficient than CAES, with efficiencies roughly 20-30 percentage points higher. However, CAES can store large amounts of energy cost-effectively and for durations of about 8 hours, which can be advantageous for certain grid-scale applications despite its lower efficiency. Lithium-ion batteries, on the other hand, are more suitable for applications requiring high efficiency and faster response times.
| Energy Storage Technology | Round-Trip Efficiency Range | Notes |
|---|---|---|
| CAES | 60% – 80% (commonly 60-65%) | Efficiency losses due to heat in compression/expansion; sometimes natural gas reheating used |
| Lithium-ion Batteries | High 80% to ~90% | Higher efficiency, less energy lost in charge/discharge cycles |
This efficiency comparison helps explain why lithium-ion batteries dominate smaller scale and fast-response storage markets, whereas CAES is still relevant for large-scale, longer duration energy storage despite its lower efficiency.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-efficiency-of-caes-compare-to-lithium-ion-batteries/
