Pumped storage projects

2nd August, 2024 Geography

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Context: Budget 2024-25 promised a policy for promoting pumped storage projects which will be brought out for electricity storage and facilitating smooth integration of the growing share of renewable energy with its variable and intermittent nature.

Details

What is a Pumped Storage Project (PSP)?

A Pumped Storage Project (PSP) is a type of hydroelectric power system that serves as a large-scale energy storage facility.

How it works?

Pumped storage plants use the principle of gravity to generate electricity.
It works by pumping water from a lower reservoir to an upper reservoir during periods of low energy demand and releasing it back through turbines to generate electricity during peak demand.
It requires power as it pumps water back into the upper reservoir.
It is a configuration of two water reservoirs at different elevations that can generate power as water moves down from one to the other, passing through a turbine.

Types of PSP

Pumped storage is of two types: on river and off river.

On-river is like any hydroelectric project supplied by a river. Existing hydro projects could become pumped storage.
Off-river projects are those that have two reservoirs at two different levels to which the water is pumped up or falls down to under gravity in a closed loop.
Abandoned mines can, for instance, be converted to such reservoirs.

Advantages and Disadvantages of pumped storage plants

Advantages

An efficient way to store excess electricity for later use.
Pumped storage plants can generate power continuously for long duration.
Helps balance supply and demand.
Can quickly generate power when demand spikes.
Infrastructure can last for decades with proper maintenance.
Generates renewable electricity without direct greenhouse gas emissions.
Ramping capability: Compared to the conventional thermal generator, PSP has a the ability of quick start-stop as well as higher ramping capability.

Disadvantages

Building reservoirs and infrastructure can be expensive
It needs the right geography to work properly
Not 100% efficient, as it loses some energy during the pumping process and over time
Regulatory hurdles and environmental concerns can slow development

PSP role in Roadmap to India’s 2030 Decarbonization Targets

At CoP 26 held in Glasgow in November 2021, India in a striking increase in its ambition over its Paris commitments declared that by 2030 it would create 500 GW of non-fossil power generating capacity.
At that time India’s installed generation capacity was 392 GW, its thermal capacity was 235 GW and non-fossil fuel capacity was 157 GW.
PSP capacity can be created to facilitate the achievement of the ambitious goal of having 500GW of non-fossil fuel capacity and its optimal utilisation.

Challenges Associated with PSPs

Fragmented Regulatory Environments for Pumped Storage Operation: Policy spectrum and compensation mechanism differs from country to country. Long clearance and approval processes, more reliance on conventional technologies.
Market Rules and Ancillary Services Compensation- In most of the economies PSPs are not remunerated for ancillary services appropriately. U.S, Germany, Australia and lately China and Japan have developed ancillary services market.
Price Volatility in Electricity Market: PSPs get benefitted with differential peak and off peak pricing.
Frequent policy changes affect the long-term return: In several economies PSPs are still reliant on government grant and low-cost funding.
Environmental Issues for PSP: PSPs require construction of large dams & reservoirs thus impact the natural water system. Concerns typically include land use changes, potential displacement of communities, and impacts on local biodiversity.
Environmental assessments are crucial to address and mitigate these impacts.
Long planning lead-times, high construction cost, and double grid fees: There are concerns in economies over lead-times during the planning & approval phase , and higher cost of construction for pumped hydro-electric storage. There is a fragmented outlook on the policy front for grid fees (ISTS charges for pumping as well as generation) and taxation.
Operation of PSP: PSPs are mostly utilized to meet peak demand and used locally. Scheduling and utilization at regional or national level is not possible in present framework in India as most of the operational PSPs belong to states.
Recognition of PSP: PSPs are considered as generating assets and no recognition and compensation for grid services are available at present.
Ancillary services: Ancillary services provided by PSPs are limited only to voltage and frequency management.
Differential Generation Tariff: Lack of differential tariff for PSP for peaking generation.

Policy Interventions Required for Growth of PSP

Defining legal identity of PSP as generation/ transmission/distribution/ grid asset.
Developing Ancillary Services Market. Resources eligible to provide essential ancillary reserves may enter into short to long term agreements with system operator to provide required ancillary services.
System Operator should specify upfront the capacity and energy requirements along with other balancing service requirements.
Regulatory framework for tariff for ancillary services provided by storage.
Single window clearance mechanism for storage projects.
Explicit policy provision that RE generators must provide firm power with a penalty if the prescribed conditions are not met.
Establishing an alternative, simplified clearance process for low impact pumped storage hydropower, such as off-channel or closed-loop projects.

Status of Pumped Storage Development in India

In 1970 India's first PHS project commenced at Nagarjuna Sagar in Telangana with an installed capacity of 705 megawatts (MW).
The current potential of ‘on-river pumped storage’ in India is 103 GW.
Nagarjuna Sagar - Telangana.
Srisailam - Telangana, plays a crucial role in both power generation and irrigation.
Kadamparai - Tamil Nadu and is known for its role in grid balancing during peak demand times.
Bhira and Ghatgar - Maharashtra.
Purulia - West Bengal, located in Ajodhya Hills.
About 44.5 GW including 34 GW off river pumped storage hydro plants are under various stages of development.

Upcoming Pumped Storage

Kurukutti-Andhra Pradesh

Global Scenario

Around 175 GW of pumped hydro storage capacity is installed worldwide as of 2022
China leads the world with 44 GW of pumped storage supporting 1,300 GW of wind and solar.
Japan with 27.5 GW, and United States with 22 GW.
The world’s first Pumped Storage plant that utilizes an abandoned mine shaft was built in the Prosper-Haniel hard coal mine in Germany.

Potential In Tamil Nadu

In Tamil Nadu, at noon on a typical day in July, wind and solar can generate half of all power. This is among the highest in the country.
On a summer day, solar plants in Tamil Nadu produce some 5,000 MW at noon.
Tamil Nadu has peaks of around 17,000 MW to 20,000 MW on a daily basis.
This year in July, maximum wind power generated reached 5,499 MW and maximum solar reached 5,512 MW.

Kadamparai plant as a role model

The plant has a higher reservoir that is at a height of around 380 m above a lower reservoir.
Each unit is a turbine generator set producing electric power when the water flows from the upper reservoir to the lower.
The same unit can function as a pump consuming electric power when it pumps water from lower to higher reservoir.
There is a power surplus coming from solar. That power is used to pump up the water at Kadamparai.
Each unit needs 20% more power to operate as pump than what it can produce as generator.
When the Kadamparai plant is operating as a pump to store energy, it would need about an hour and half to switch to generating mode. When stopped, it would need about half hour to start and generating at full load.
When solar generation stops and the evening peak load begins after 6pm, Kadamparai plant becomes a generato It can produce 400 MW of full power for three to four hours and help support the evening peak loads.
When the solar is coming in full, power managers in the State stop drawing power from hydro of which the State has around 1,000 MW.