The relevance of pumped storage projects

Sub: Geo

Sec: Hydrology

Context:

The Union Budget for 2024-25 announced a policy to promote pumped storage projects for electricity storage and the integration of renewable energy.

Pumped Storage hydropower (PSH):

Solutions for storing variable renewable energy include batteries and compressed air storage, but pumped storage using water is widely adopted.
Pumped storage functions like large batteries, using water to store and generate power.

How does pumped storage hydropower work?

Water is pumped from the lower reservoir to the upper reservoir in times of high electricity supply, such as during the day when electricity can be supplied by the sun’s charging of solar panels, and/or low demand.
In times of reduced electricity supply and/or high demand, such as at night, when some electrical load remains but the sun is not shining and solar energy is inaccessible, water from the upper reservoir is released to the lower reservoir, generating electricity as it moves down through a turbine.

Types of Pumped Storage Hydropower:

On-river projects are similar to hydroelectric projects supplied by a river.
Off-river projects have two reservoirs at different levels, creating a closed loop for water to be pumped up or let down to generate power.
The Kadamparai project in Tamil Nadu is an example of off-river pumped storage.

Operation of Kadamparai Pumped Storage Plant:

Tamil Nadu generates half of its power from wind and solar at noon.
Solar power in Tamil Nadu peaks at around 5,000MW at noon but drops to zero at sunset.
Kadamparai plant, established 37 years ago, has four 100MW units.
The plant uses surplus solar power to pump water to a higher reservoir during the day.
Each unit requires 20% more power to pump water than it generates, but it uses solar energy, saving fuel.
The plant switches from pumping to generating mode to support evening peak loads, producing 400MW of power for three to four hours.
The upper reservoir has around 1 TMC feet of water, replenished by natural rainfall.

Importance of Pumped Storage:

India aims to create 500GW of non-fossil fuel energy by 2030.
From 2021 to 2023, 23GW of non-fossil generation capacity was added, with 7.5GW from wind and solar energy in 2023-24.
Renewable power generation will increase but will be variable and “infirm”.
Policies prioritize using all generated renewable power, with curtailment as a last resort.
Advanced forecasting helps grid operators plan power generation from other sources to maintain a steady supply.

India’s Pumped Storage Capacity:

India has 3.3GW of pumped storage, with key projects in Nagarjunasagar, Kadana, Kadamparai, Panchet, and Bhira.
China leads with 50GW of pumped storage.
India needs to significantly increase its pumped storage capacity to meet renewable energy targets.

Source: TH