Pumped Hydroelectric Energy Storage
Pumped hydroelectric energy storage (PHES or PSH) is the largest and most established form of grid energy storage globally, accounting for over 94% of installed energy storage capacity. Here is how it compares to other renewable energy storage technologies across several key attributes:
Efficiency and Duration
- Pumped hydroelectric storage systems have a round-trip energy efficiency typically between 70% and 80%, with some claims up to 87%. Another source cites over 80% efficiency through a full cycle.
- Pumped storage can provide long-duration electricity supply, typically about 10 hours of continuous output.
- In contrast, lithium-ion battery systems generally provide about 6 hours of electricity storage per cycle.
- Other technologies like compressed-air energy storage (CAES) and various types of batteries (e.g., lead-acid, vanadium redox flow) generally focus on different durations, with PSH and CAES suited for long-duration bulk storage, while batteries mostly serve shorter timeframes.
Capacity and Scale
- PSH facilities are very large scale, with individual plants often on the order of hundreds of megawatts to gigawatts of power capacity and gigawatt-hours of energy storage capacity.
- It is the dominant technology for bulk grid storage worldwide, with over 127,000 MW of installed capacity reported by 2012.
Economics and Resource Use
- PSH requires significant upfront capital investment and long amortization periods, which can deter some investors, in contrast to the declining costs and faster deployment of lithium-ion battery systems.
- The raw material and land requirements differ substantially between PSH and battery storage; PSH needs suitable geography (height difference and water availability) and significant land.
- Batteries require different raw materials, often critical minerals, while PSH relies primarily on civil engineering and water resources.
Environmental Impact
- PSH has a relatively low carbon footprint compared to other bulk storage options; it emits about a quarter of the greenhouse gases associated with compressed-air energy storage.
- However, PSH can face ecological and social challenges due to the need for suitable sites which are often in hilly or mountainous regions, sometimes in areas of environmental sensitivity.
Grid Services and Applications
- PSH is particularly valuable for providing long-duration energy storage and grid services such as load balancing over hours, grid inertia, and resilience.
- Batteries are typically better suited for shorter-duration storage, fast response services, and distributed energy applications.
Summary Table: Pumped Hydroelectric Storage vs. Other Technologies
| Attribute | Pumped Hydroelectric Storage | Lithium-ion Batteries | Compressed-Air Energy Storage (CAES) | Other Batteries (Lead-acid, Vanadium Redox, etc.) |
|---|---|---|---|---|
| Efficiency (Round-trip) | >70-87% (typically 80%+) | >85-95% | >50-70% (varies) | Varies, generally 70-85% |
| Duration | >10 hours | >6 hours | Long-duration | Short to medium duration |
| Scale | Very large (>100 MW to GW scale) | Modular, smaller scale | Large scale | Medium scale |
| Cost | High upfront, long payback | Declining costs, faster deployment | Moderate to high | Moderate |
| Environmental Impact | Low carbon footprint, site impacts | Moderate, mining impacts | Higher emissions than PSH | Varies |
| Site Requirements | Needs water & elevation differences | Flexible location | Geological formations needed | Flexible location |
| Grid Services | Bulk energy, inertia, resilience | Fast response, short-term balancing | Bulk energy, some inertia | Short-term balancing |
Pumped hydro remains the backbone of grid-scale renewable energy storage due to its long duration, large scale, and high efficiency, but is limited by geography and higher capital costs. Batteries and other technologies complement it by offering flexible, smaller-scale, and faster-response storage options.
This holistic comparison is supported by recent analyses and industry studies indicating that pumped storage hydropower, while mature and efficient, faces competition from falling battery costs and other technologies, necessitating a balanced portfolio of storage solutions to meet renewable energy goals.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-pumped-hydroelectric-energy-storage-compare-to-other-renewable-energy-storage-technologies/
