Pumped hydroelectric energy storage (PSH) stands out among long-duration energy storage technologies primarily due to its large capacity, efficiency, and service duration, but also has specific geographical and environmental limitations.
Comparison of Pumped Hydroelectric Storage with Other Technologies
Capacity and Scale
- PSH is by far the largest-capacity form of grid energy storage globally, accounting for over 94% of installed energy storage capacity and more than 99% of bulk storage capacity worldwide, with around 127,000 MW capacity reported as of 2012.
- Its average facility can store very large amounts of energy, exemplified by average closed-loop pumped storage hydropower facilities with capacities around 835 MW and annual energy delivery of about 2,060 GWh.
Duration and Use Case
- PSH typically offers about 10 hours of electricity supply per cycle, making it suitable for long-duration energy storage and grid balancing over extended periods.
- In contrast, lithium-ion batteries generally provide around 6 hours of electricity supply, targeting shorter duration applications.
- PSH and compressed-air energy storage (CAES) are designed for long-duration storage, whereas batteries like lithium-ion, lead-acid, and flow batteries are aimed at shorter timeframes.
Efficiency
- The round-trip energy efficiency of PSH ranges from roughly 70% to 80%, with some claims as high as 87%, and generally above 80% efficiency through a full cycle.
- Battery technologies may have comparable or higher efficiencies for shorter cycles, but over long durations, PSH remains highly competitive.
Environmental and Geographic Considerations
- PSH requires specific geography: availability of suitable terrain with elevation differences and water resources, usually in hilly or mountainous areas. This limits site feasibility and can raise ecological and social concerns.
- Batteries and CAES have more flexibility in siting but may have other environmental impacts such as resource extraction for battery materials or emissions for compressed air systems. Notably, PSH has significantly lower greenhouse gas emissions compared to CAES.
Economic Factors
- Studies comparing stationary battery storage systems and pumped storage plants emphasize PSH’s cost-effectiveness for large-scale, long-duration applications, although exact costs depend on site and technology specifics.
Summary Table: Pumped Hydroelectric vs. Other Long-Duration Storage
| Feature | Pumped Hydroelectric Storage (PSH) | Lithium-ion Batteries | Compressed-Air Energy Storage (CAES) | Flow Batteries / Lead-acid Batteries |
|---|---|---|---|---|
| Storage Duration | ~10 hours | ~6 hours | Long-duration | Short to medium duration |
| Installed Capacity Share | >94% of global storage capacity | Significant but smaller scale | Smaller scale | Smaller scale |
| Round-trip Efficiency | 70-80% (up to 87%) | ~80-90% | Lower than PSH | Variable (lower than PSH) |
| Environmental Impact | Low GHG emissions, site-dependent | Resource intensive mining | Higher GHG than PSH | Depends on chemistry |
| Site Requirements | Specific geography (elevation + water) | Flexible | Flexible | Flexible |
| Cost Efficiency | Cost-effective for large-scale | Higher cost per kWh storage | Moderate | Varies |
Overall, pumped hydroelectric energy storage excels in large-scale, long-duration grid applications due to its high capacity and robust efficiency, outperforming batteries in duration and scale, and offering lower emissions and cost advantages over CAES. Its main limitations are site-specific requirements and environmental considerations related to reservoir construction and water use.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-pumped-hydroelectric-energy-storage-compare-to-other-long-duration-energy-storage-technologies/
