Hydro Pumped-Storage Projects (PSPs)
Context:
The Central Electricity Authority (CEA) has released a roadmap to fast-track the development of PSPs, aiming for a capacity of 100 GW by 2035-36.
The CEA has recommended allowing PSPs within Eco-Sensitive Zones (ESZs) and within the 10-km buffer of protected areas where ESZs are not notified.
Currently, these are prohibited in such areas.
The roadmap calls for relaxing stringent conditions applicable to the Western Ghats to facilitate project development.
This "regulatory reset" aims to address the storage challenges posed by the increasing share of variable renewable energy (solar/wind) in India's power mix.
The move comes amidst protests in states like Tamil Nadu and Karnataka regarding risks to forests and biodiversity.
About PSPs:
PSPs use the gravitational potential of water to store electricity.
They pump water from a lower to an upper reservoir during off-peak hours (surplus generation) and release it through turbines during peak demand.
They are considered the "Water Battery" for the grid, providing inertia, balancing power, and helping integrate renewable energy.
Types of PSPs:
Based on their interaction with river systems, PSPs are generally classified into two categories:
Off-Stream (Closed-Loop) PSPs:
It involves only one reservoir being located on a river, stream, or nallah, while the other reservoir is situated away from any perennial watercourse.
Compared to on-stream schemes, off-stream open loop projects reduce the extent of river disturbance but still retain some dependence on natural hydrology.
These projects do not involve damming or diverting natural rivers.
They have minimal impact on river ecology, aquatic life, and sediment transport since they don't alter downstream flow.
On-Stream PSPs:
Both the upper and lower reservoirs are located directly on a river, stream, or nallah.
Such projects have a direct interaction with the natural river flow and hydrology.
They are subject to stricter environmental scrutiny and "hydrological risk" (dependent on river inflows) compared to off-stream projects.