The shift toward a cleaner and more sustainable energy system is increasingly relying on advanced energy storage technologies. As solar and wind power become a larger part of the electricity mix, managing their variable nature has become a major challenge for power grids. Energy storage is now seen as a key solution to store excess electricity and maintain grid stability in real time. In this context, the Central Electricity Authority (CEA) of India, along with the Danish Energy Agency, has released the Indian Technology Catalogue for Energy Storage 2026, which offers a common framework to assess and compare different storage technologies.
Energy storage systems mainly serve two types of functions. The first is power-intensive services, which need very fast response times. These include services such as frequency regulation and voltage support, where the system must react within seconds or minutes to keep the grid stable. The second is energy-intensive services, which focus on storing large amounts of electricity for longer periods. This allows power to be stored when prices are low and released during peak demand, a process often called time-shifting or energy arbitrage. For many years, pumped hydro storage has played a major role in these applications, but battery-based technologies are now gaining strong momentum.
Among electrochemical storage options, lithium-ion batteries have become the most widely used technology for grid-scale projects. These batteries work by moving lithium ions between two electrodes through a liquid electrolyte during charging and discharging. Two main lithium-ion chemistries are commonly used. Nickel Manganese Cobalt batteries offer high energy density, which means they can store more energy in a smaller space. Lithium Iron Phosphate batteries, on the other hand, are known for better safety and longer life, making them suitable for many stationary storage projects.
Lithium-ion systems are highly scalable because of their modular design. Individual battery cells are combined into modules, which are then assembled into racks and large containers. A single 40-foot container can typically store between 4 and 6 megawatt-hours of energy. However, lithium-ion batteries also have certain limits. They slowly lose charge over time, making them unsuitable for storage over several months. Their lifespan is also limited, usually ranging from a few thousand to around ten thousand full charge and discharge cycles.
To address cost and sustainability concerns, sodium-ion batteries are now moving closer to commercial use. These batteries operate in a similar way to lithium-ion systems but use sodium instead of lithium. Sodium is much more abundant and widely available, which could help reduce costs and supply risks. Sodium-ion technology has reached an advanced development stage, with successful large-scale demonstrations already in operation.
The main advantage of sodium-ion batteries is their lower material cost and reduced environmental impact. However, there are technical challenges. Sodium ions are larger and heavier, which slows down movement inside the battery and reduces performance at high discharge rates. Current commercial projects show lower energy density compared to lithium-ion batteries, but they offer good safety and a low self-discharge rate. These features make sodium-ion batteries suitable for stationary storage and some mobility applications.
As energy storage needs continue to grow, the choice of technology will depend on grid requirements. Lithium-ion batteries are expected to remain dominant in high-performance roles, while sodium-ion batteries are likely to expand as production increases and costs fall. Together with other storage options such as pumped hydro and hydrogen, these technologies will play a vital role in supporting a renewable-based energy system.
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