Hydropower

Hydropower is a mature technology, yet it continues to evolve. Reservoir hydropower plants and pumped storage plants are particularly suited to providing system flexibility, while run-of-the river hydropower plants are themselves variable according to current or seasonal weather conditions.

Run-of-river hydropower plants harness energy for electricity production mainly from the available flow of the river. These plants may include short-term storage or "pondage", allowing for some hourly or daily flexibility but they usually have substantial seasonal and yearly variations.

Reservoir hydropower plants rely on stored water in a reservoir. This provides the flexibility to generate electricity on demand and reduces dependence on the variability of inflows. Very large reservoirs can retain months or even years of average inflows and can also provide flood protection and irrigation services.

Pumped storage plants use water that is pumped from a lower reservoir into an upper reservoir when electricity supply exceeds demand or can be generated at low cost. When demand exceeds instantaneous electricity generation and electricity has a high value, water is released to flow back from the upper reservoir through turbines to generate electricity. Pumped storage currently represents the overwhelming majority of on-grid electricity storage.

Last updated Nov 24, 2020