Recently, the Velimalai Pumped Storage Hydro Electric Project received Terms of Reference (ToR) clearance from the Union Ministry of Environment, Forest and Climate Change. The project is a major step towards enhancing renewable energy integration, energy storage, and peak power management in Tamil Nadu.
About Velimalai Pumped Storage Hydro Electric Project
The project is a 1,100 MW pumped storage hydropower plant proposed at Vellimalai in the Kanyakumari district of Tamil Nadu.
It is the first pumped storage project in Tamil Nadu to be developed under the Public-Private Partnership (PPP) model on a Build-Own-Operate-Transfer (BOOT) basis under Section 63 of the Electricity Act.
The project aims to:
- Strengthen peak electricity demand management
- Support round-the-clock renewable energy supply
- Enhance grid stability
- Store surplus renewable energy
Key Features of the Project
Closed-Loop Off-River System
The project is designed as a closed-loop off-river pumped storage system, meaning:
- Both reservoirs will be artificially created
- The system will not depend on perennial rivers
- Water will circulate repeatedly between reservoirs
This minimizes ecological disruption and reduces dependence on natural river flows.
Reservoirs
Upper Reservoir
- Gross storage capacity: 4.39 million cubic metres
Lower Reservoir
- Located upstream of the existing Mambazhathuraiyar Dam
- Gross storage capacity: 4.91 million cubic metres
Power Generation Mechanism
The project works through:
- Pumping water to the upper reservoir during off-peak hours using surplus electricity
- Releasing water during peak demand periods to generate electricity
Key Operational Data
- Water pumped: ~3.94 million cubic metres
- Pumping duration: 6.94 hours
- Electricity generation: 6 hours daily
- Estimated annual energy generation: 2,080.55 million kWh
Infrastructure
The project will include:
- Underground powerhouse
- Four generating units of 275 MW each
Significance of Pumped Storage Projects
Renewable Energy Integration
Pumped storage projects help integrate intermittent renewable sources such as:
- Solar energy
- Wind energy
Grid Stability
They provide:
- Frequency regulation
- Peak load balancing
- Emergency backup power
Energy Storage
Pumped hydro storage acts as a large-scale “battery” by storing surplus energy for later use.
Climate Goals
Such projects support India’s clean energy transition and net-zero ambitions.
Advantages of Closed-Loop Systems
Compared to traditional hydropower projects:
- Lower ecological impact
- Reduced river diversion
- Controlled water circulation
- Better operational flexibility
Challenges
Potential concerns include:
- Environmental impacts during construction
- Land acquisition issues
- Forest clearance and biodiversity concerns
- High initial capital costs
Conclusion
The Velimalai Pumped Storage Hydro Electric Project represents a significant advancement in India’s renewable energy storage infrastructure. By enabling efficient energy storage and supporting grid reliability, the project can play a crucial role in India’s transition toward a cleaner and more sustainable energy future.