Pumped Hydro Storage: One Of The Most Widely Used Commercially Established Technologies

 

Pumped Hydro Storage

Pumped hydro storage is one of the most efficient and largest-scale methods of storing renewable energy currently available. It works by pumping water from a lower elevation reservoir to a higher elevation when energy is abundant and inexpensive to produce, and then releasing it through turbines to a lower reservoir to generate electricity when demand is high. This process effectively stores potential energy in the form of water that can be converted back to electrical energy on demand.

What is Pumped Hydro Storage?

Pumped hydro storage is a type of hydroelectric energy storage that uses energy from energy sources like solar or wind and stores it for later use. It involves pumping water from a lower elevation reservoir to a higher reservoir during off-peak hours when energy is cheapest. Later, when energy demand is highest, usually during the daytime, the stored water is released from the upper reservoir through turbines to generate electricity.

The basic components needed for Pumped Hydro Storage include two water reservoirs at different elevations and reversible turbine pumps capable of pumping water from the lower reservoir to the upper one and generating electricity when water flows back down. The higher the elevation difference between the reservoirs, the more potential energy is stored in the system and the more electricity can be generated.

Advantages of Pumped Hydro Storage
There are several key advantages of pumped hydro storage systems:

Large Storage Capacity: Pumped hydro facilities can store massive amounts of potential energy economically thanks to large reservoirs. Some facilities can store energy equivalent to millions of kilowatt-hours.

Proven Technology: Pumped hydro storage has been used commercially for over 100 years and is considered a mature, dependable storage technology.

Fast Response: Pumped hydro facilities can ramp energy production up or down very quickly, often within seconds, making them well-suited for balancing intermittent renewable energy sources.

Lifespan: Pumped hydro facilities have lifespans of over 100 years with proper maintenance and upgrades. This makes the infrastructure investments very cost-effective over the long-term.

Efficiency: With typical roundtrip efficiencies around 75-80%, pumped hydro converts a large percentage of input energy back into electricity with low energy losses.

Lower Cost: At large scales of over 100 MW capacity, pumped hydro energy storage has lower overall costs than competing battery technologies.

Types of Pumped Hydro Facilities

There are three main types of pumped hydro storage facilities:

Conventional Pumped Storage - Involves two adjacent water reservoirs at different elevations connected by reversible pumps and turbines within a solid structure. Most existing large-scale pumped hydro plants fall under this category.

Off-river Closed-loop Pumped Storage - These facilities use an upper and lower reservoir not directly connected to a river. This type avoids disruption to the natural water cycle.

In-river Pumped Storage - Here, the lower reservoir is a natural water body like a river or lake, while the upper is artificially created. Water is discharged back into the lower reservoir to generate power.

Examples of Pumped Hydro Projects

Some of the largest and most well-known pumped hydro projects currently in operation around the world include:

Bath County Pumped Storage Station (VA, USA) - 3,000 MW capacity with 1,595 foot elevation difference
Dinorwig Power Station (Wales, UK) - 1,800 MW capacity using abandoned slate mines
Edward Hyatt Pumped Storage Plant (CA, USA) - 1,200 MW capacity utilizing two rock excavated reservoirs.
Grande-Dixence Dam (Switzerland) - 900 MW capacity, utilizing an 800 meter elevation difference
Tehachapi Pumped Storage Project (CA, USA) - over 2,000 MW planned capacity with separate day and night-use reservoirs.

Raccoon Mountain Pumped-Storage Plant (TN, USA) - over 2,400 MW capacity utilizing a 535 foot elevation difference.

Potential Growth and Opportunities

There are still vast opportunities worldwide to develop new pumped hydro storage facilities or expand existing ones to meet rapidly growing renewable energy integration needs. Some projected growth areas for pumped hydro include:
Pairing with large offshore wind farms to balance intermittent power supply.
Developing many small to medium scale plants (25-500 MW) using versatile closed-loop designs at lower costs.
Increasing potential in mountainous regions like the Andes or Himalayas to benefit from natural elevation drops.
Expanding existing hydroelectric facilities with added pumped storage capabilities.
Integrating with concentrated solar power plants for grid-scale energy storage.
Retrofitting abandoned mines, quarries, and other geological features for closed-loop pumped storage schemes.
Pumped hydro storage represents one of the most practical large-scale energy storage methods currently available to support increasing shares of variable wind and solar power on the electric grid. Its ultra-large capacity, long life, low costs, and ability to respond very quickly make it ideal for renewable energy integration at utility-scales. As more energy is derived from intermittent renewable sources worldwide, expect pumped hydro storage to play an even greater role in balancing power supplies to meet fluctuating electricity demand around the clock.

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