Pumped hydroelectric energy storage (PHES) and lithium-ion batteries are both key technologies for grid energy storage, but they differ notably in their efficiency and operational characteristics.
Efficiency Comparison
- Pumped Hydro Storage Efficiency: The round-trip efficiency of pumped hydroelectric storage generally ranges from about 70% to 80%, with some sources citing values slightly higher, up to 87% in certain studies. This means that 70-80% of the energy used to pump water to a higher elevation can be recovered when the water is released to generate electricity.
- Lithium-ion Battery Efficiency: Lithium-ion batteries typically have higher round-trip efficiencies, often in the range of 85% to 95%. This means lithium-ion batteries lose less energy during the charge-discharge cycle compared to pumped hydro storage.
Additional Context
- Although lithium-ion batteries have higher efficiency, pumped hydro storage is currently the largest-capacity form of grid energy storage worldwide and can provide longer-duration storage (typically about 10 hours or more), whereas lithium-ion batteries are often more suited to shorter duration applications.
- PHES plants operate by converting electrical energy into gravitational potential energy by pumping water uphill and then generating electricity via turbines when demand peaks. This process entails energy losses due to pumping and turbine inefficiencies, explaining the 70-80% efficiency range.
- Lithium-ion batteries store energy chemically and convert it back to electricity with comparatively less loss, hence higher efficiency but they generally have shorter lifespans and are more costly at large scales for long-duration storage.
Summary Table
| Storage Type | Round-trip Efficiency | Typical Discharge Duration | Scale of Storage |
|---|---|---|---|
| Pumped Hydro Storage | 70% – 80% (up to ~87%) | ~10 hours or more | Largest grid-scale storage (~1.6 TWh global capacity) |
| Lithium-ion Batteries | 85% – 95% | Usually shorter (hours) | Widely used for short to medium duration storage |
In conclusion, while lithium-ion batteries typically exhibit higher round-trip efficiency than pumped hydroelectric storage, pumped hydro compensates with vastly greater storage capacity and longer discharge durations, making it invaluable for large-scale grid balancing especially alongside intermittent renewables like wind and solar.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-efficiency-of-pumped-hydroelectric-energy-storage-compare-to-lithium-ion-batteries/
