As share of renewables increases in grid, Govt explores storage options

In India, which is the world’s third largest producer of renewable energy, nearly 40 per cent of installed electricity capacity comes from non-fossil fuel sources. This green push has resulted in a sharp 24 per cent reduction in emission intensity of GDP between 2005 and 2016, but it has also thrown up challenges of a grid being increasingly powered by renewables.

Even as the Lithium-ion storage battery option for grid application is now being ruled out as unviable, at least for now, an emerging policy resolve is that solar and wind-based generation cannot continue to be pushed down to struggling electricity distribution companies or discoms. The renewables challenge is compounded by the fact that SECI (Solar Energy Corporation of India Ltd) — the state-owned company conducting solar auctions — has locked a number of contracts involving green developers in rigid PPAs (power purchase agreements) with no scope for innovation, according to sectoral experts.

Energy storage is needed alongside green energy sources to primarily balance out the variability in renewable generation – electricity is generated only when the sun shines or when the wind blows. This is not always in sync with the demand cycle. Storage can help tide over this shortcoming associated with renewables.
For procurers such as state-owned discoms, renewables are not always a viable option precisely due to these vagaries in the generation trends, which means they still have to depend on thermal or nuclear generation for meeting base load demand. Renewables bundled with a viable storage option help overcome this problem.

There are two alternatives being considered by the government now: hydrogen and hybrid generation models blended with off-stream pumped storage. In 2023, as the hidden challenges of RE (Renewable Energy) transition are likely to manifest more concretely, the government is making a renewed push on both technologies. A policy for stepping up green hydrogen production and tapping into its potential as a fuel has just been cleared by the cabinet. The Union Ministry of Power has also wrapped up a survey of all pumped hydro sites and hydro PSUs have been given a target of taking up pumped hydro schemes. The Ministry of Power has also written to the Union Coal Ministry to consider the option of opencast mines as potential sites for pumped hydro in the future.

Key constraints:

i)The main challenge is non-availability of natural gas to run gas turbines to complement the growing RE capacity in the generation mix. India’s vast fleet of coal-based power plants of 200 MW series are more than 25 years old, run on old technology and do not promise robust reliability. Further, considering that India’s load demand is far from saturated, there is the need to replace obsolete coal-based plants with supercritical highly-efficient coal-based plants as an intermediate goal for total transition. However, this may not be acceptable to the international community in view of the impending climate crisis.

“India will have to carefully balance its act. We must reduce the percentage of coal-based capacity by closing the inefficient fleet and yet add new flexible capacity to meet load requirements. There should be provision to convert coal-based capacity to a fuel mix of gas and hydrogen,” Ravinder, former Chairman of the Central Electricity Authority (CEA) said.

On the specific concerns of energy storage considering the bulk of capacity addition is coming through renewables, a senior government official said one of the requirements is storage and the other is the flexibility of thermal power plants. “We’ve already issued a regulation that the thermal power plants will be flexible up to 55 per cent. In the next phase, after three years, we have to go down to 40 per cent, which means in the daytime, they would run at 40 per cent and pick up after sunset. Now, battery storage is expensive at Rs 10 per kilowatt per hour… There is a fresh impetus to pursue pumped hydro projects,” the official said.

ii) The country’s current installed generation capacity is 404 GW (1 gigawatt is 1,000 megawatt) while the maximum demand is around 215 GW. Of the installed capacity, the total electric power installed capacity from non-fossil fuel-based energy resources was 173.14 GW as on November 30, 2022, which is 42.3 per cent of the total electric power installed capacity, primarily solar and wind. To compensate for the intermittency, pumped-storage hydroelectric plants – where it stores energy in the form of the gravitational potential energy of water that is generally pumped from a lower elevation reservoir to a higher elevation reservoir when renewable power is available, which is then released to move a turbine to generate electricity when renewable generation is not available – is being seen as the most viable alternative.

These projects thereby work similarly to a giant battery, because they can store power and then release it when needed. According to the 2021 edition of the Hydropower Market Report, pumped storage hydropower currently accounts for 93% of all utility-scale energy storage in the United States. PSH reservoirs, though, can have ecological impact on the area that they come, in line with the kind of problems faced by reservoir based hydro projects.

The Central Electricity Authority, the policy arm of the Union Ministry of Power, has assessed a requirement of 41 GW/190 GWh (gigawatt hour) of Energy Storage System for integration of 500 GW of non-fossil fuel-based electricity into the grid by 2030. The India Energy Storage Alliance, an industry alliance focused on development of energy storage, green hydrogen and e-mobility has estimated the requirement of about 160 GWh of Energy Storage System by 2030 in a report titled “Energy Storage Vision 2030 for India”.