Battery Storage and India’s Energy Transition

  Dec 17, 2020

Battery Storage and India’s Energy Transition

With an installed capacity of 73.74 GW of variable renewable energy (VRE) of solar and wind, India ranks fourth in the world behind China, the US and Germany. Of the total installed capacity of 372.69 GW, VRE accounts for 19.79%.

Daily reports of power supply at Power System Operation Corporation Limited(POSOCO), a national agency that handles load despatch functions, show that the percentage of renewables in the energy mix generally vary between 6% and 10% over one month. This indicates that the potential of VRE installed capacity is not fully utilised.

With no facility to store electricity as of now, the electricity produced in the power plants and fed into the grid should ideally be the same as the electricity consumed. If the electricity demand is more than the supply, the frequency at which the grid equilibrium is maintained (50 Hertz) will come down and vice versa. An imbalance in frequency when it goes beyond permissible limits leads to grid collapse and blackout (power outage).

Since solar radiation and wind speed keep varying, the frequency cannot be maintained at 50 Hz. Electricity demand also keeps varying. Hence grid operators cannot match supply and demand, if only power from VRE sources is fed into the grid. Since these technical limitations hamper more absorption of renewable energy, a mix of thermal and hydro power are used for maintaining the balance, since power output from these plants can be controlled.

Storage battery for grid stability

India has a target of 175 GW of renewables by 2022. As the country transitions more towards renewable energy sources, it is becoming imperative to ensure grid stability. One of the solutions for a balanced grid is energy storage batteries. When the energy generation is more than the demand, it can be stored in the batteries and used when generation comes down and/or demand increases.

Batteries have been in use for long, but not on a scale that could support the grid. The world’s first and largest grid-scale battery called Hornsdale Power Reserve (HPR) came up in South Australia in 2017, after the state had a blackout in September 2016. The 100 MW capacity power reserve, runs on lithium-ion battery.

Lithium ion, lead acid, redox flow, molten salt (sodium sulphur) are the battery storage technologies that are available today. However, the 2019 Nobel winning Lithium ion (Li-ion) technology dominates the market. Li-ion would be ideal for hourly or daily applications like peak shaving (managing demand to eliminate demand spikes) and grid stability as they have high efficiency and power handling capacity, besides decreasing prices. Further, maintenance required in lithium batteries is very less and they have small footprint due to their high energy density.

India’s first grid-scale battery is at a substation located at Rohini, New Delhi, operated by Tata Power-Delhi Distribution Limited (DDL) since 2019. Tata Power collaborated with AES Corporation and Mitsubishi Corporation to set up Asia’s largest grid-scale battery energy storage system (BESS) at Rohini. At the 10MWh plant, Li-ion battery is used to operate the plant seamlessly.

It has been extensively used for peak load management, deviation settlement mechanism management, etc. and provides enhanced power supply, by addressing various technical issues. The battery occupies 625 sq.m, covering the BESS, isolation transformer and fire fighting installation. There is scope for reduction in space with container-based solutions.

Cost factor: Battery price which was more than $1,100 per kilowatt-hour (kWh) in 2010, came down to $156/kWh in 2019. The price is expected to reach $100/kWh by 2025.

Once battery costs come down, renewable energy generators (REGs) will be eager to add battery storage to their portfolio.

Further improvements in battery technology and more efficient integration into complete energy storage systems are expected to further reduce costs. A large increase in global battery manufacturing associated with deployment of electric vehicles is also expected to reduce battery costs for grid-scale battery storage.