While battery storage often dominates the conversation around energy storage, thermal and mechanical storage systems present significant opportunities for decarbonization, particularly in India. These storage technologies offer alternatives to electrochemical storage, providing solutions that can be crucial for balancing renewable energy supply and demand.
India is exploring various thermal and mechanical storage technologies to enhance the reliability and efficiency of its renewable energy systems. Pumped hydro storage is currently the most established technology, but innovations in phase change materials (PCM), compressed air, and other mechanical storage systems are gaining traction.
Mechanical Storage Solutions
Pumped Hydro Storage (PHS): Current Capacity: India has an installed capacity of approximately 4.8 GW of pumped hydro storage, with projects like the Srisailam Dam (900 MW) and the Kadamparai Pumped Storage Plant (400 MW).
Compressed Air Energy Storage (CAES): India is in the early stages of exploring CAES. Pilot projects in states like Andhra Pradesh are being considered, with a potential capacity of 300 MW by 2030. Advantages: CAES can provide large-scale storage with quick response times, making it suitable for grid balancing and integration with intermittent renewable sources like wind and solar.
Compressed Air and CO2-Based Thermal Storage: Research institutions like IIT Bombay and companies like Tata Power are exploring CAES and CO2-based thermal storage technologies.
Flywheel Energy Storage: Flywheel storage is being researched for its ability to provide short-term energy storage and grid stability services. While not yet deployed at large scale, flywheel systems offer promise for high-frequency regulation and short-duration energy needs.
Thermal Storage Solutions
Phase Change Materials (PCM): Molten Salt Storage: CSP plants in India, such as the 50 MW Godawari Green Energy plant in Rajasthan, utilize molten salt for thermal storage. These systems can store heat during the day and release it at night, ensuring continuous power generation. Ice-Based Storage: These systems use electricity during off-peak hours to freeze water, which then provides cooling during peak hours, reducing the load on air conditioning systems.
Thermal Energy Storage (TES): TES is being used in industrial applications for process heating. Projects in Gujarat and Maharashtra are integrating TES with solar thermal systems to provide consistent heat for industrial processes, reducing reliance on fossil fuels.
Residential and Commercial Use: Simple heat storage systems, such as solar water heaters and hot water tanks, are widely used across residential and commercial sectors.
Srisailam Pumped Storage Project
Overview: This 900 MW project in Andhra Pradesh is one of India's largest pumped hydro storage facilities. It plays a critical role in balancing grid demand and integrating renewable energy sources.
Impact: By storing excess energy during low-demand periods and releasing it during peak demand, the Srisailam project helps stabilize the grid and reduce reliance on fossil-fuel-based power plants, saving approximately 2.25 million tons of CO2 annually.
Godawari Green Energy CSP Plant
Overview: Located in Rajasthan, this 50 MW CSP plant uses molten salt for thermal storage, enabling it to provide power even after sunset.
Impact: The plant demonstrates the potential of CSP with thermal storage in India's renewable energy mix, contributing to grid stability and reducing carbon emissions by about 120,000 tons annually.
Thermal and mechanical storage technologies offer substantial decarbonization potential for India. With continued innovation and supportive policies, these technologies will play a critical role in India's journey towards a sustainable and low-carbon future by 2030. The cumulative impact of these technologies could result in annual CO2 reductions of approximately 70-90 million tons, significantly contributing to India's climate goals.
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