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Pumped-storage hydroelectricity (PSH)
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- Context:The 1,100 MW Velimalai Pumped Storage Hydro Electric Project in Kanniyakumari district has been granted Terms of Reference (ToR) clearance by the Union Ministry of Environment, Forest and Climate Change.
- The project, proposed by the Tamil Nadu Green Energy Corporation Limited (TNGECL).
About Pumped-storage hydroelectricity (PSH)
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- Pumped Storage Hydropower (PSH), or ‘Pumped Hydro Energy Storage’ (PHES), is a method used to store energy within power systems and to balance electricity demand.
- In this method, water is pumped from a lower reservoir to an upper reservoir in order to store energy as ‘gravitational potential energy.’
- The electricity required for the water-pumping process is typically utilized during ‘off-peak hours’—periods when electricity is inexpensive and demand is low.
- During times of peak electricity demand, the stored water is released to flow through turbines located below, thereby generating electricity.
- Although PSH systems consume more energy than they produce—due to energy losses incurred during the pumping process—they remain highly economically viable because the generated electricity can be sold at a higher price during peak demand periods.
PSH systems are primarily categorized into two types:
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- Open-loop systems: Systems that are continuously connected to a natural water source, such as a river.
- Closed-loop systems: Standalone systems in which water circulates between two reservoirs without any significant natural inflow of water.
- PSH power plants can be established either by utilizing existing dams or by constructing two reservoirs at different elevations (including storage facilities situated on mountain peaks).
- In India, approximately 120 potential sites suitable for PSH projects have been identified; it is estimated that these sites could collectively generate approximately 120 Gigawatts (GW) of electricity.
