Latest inventions in science and technology Pumped-storage hydroelectricity (PSH) 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) 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: 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.
