As grid share of renewables increases, government explores storage options

TO OPERATIONALLY SUSTAIN a massive monthly addition of an average of 1,000 megawatts (nearly five times the amount of power produced by a 250 MWe nuclear plant) from non-fossil or renewable fuels to the electricity grid, lawmakers say India urgently needs work on developing viable energy storage options.

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

Despite the fact that the lithium-ion battery storage option for on-grid application is now ruled out as unfeasible, at least for now, an emerging policy resolution is that solar and wind generation cannot continue to be pushed into the mainstream. 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 that runs solar power auctions, has locked up a series of contracts involving green developers in rigid PPAs. energy purchase) with no room for innovation. , according to sector experts.

Energy storage is needed along with green energy sources to mainly balance 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 overcome this deficiency associated with renewable energy.
For buyers like state-owned discoms, renewables are not always a viable option precisely because of these vagaries in generation trends, which means they still have to rely on thermal or nuclear generation to meet baseload demand. . Renewables combined with a viable storage option help overcome this problem.

The government is currently considering two alternatives: hybrid and hydrogen generation models combined with off-stream pumped storage. In 2023, as the hidden challenges of the RE (renewable energy) transition are likely to manifest themselves in more concrete ways, the government is giving renewed impetus to both technologies. The cabinet has just approved a policy to increase the production of green hydrogen and harness its potential as a fuel. The Union Ministry of Energy has also concluded a survey of all pumped hydro sites and hydro PSUs have been given the target to take on pumped hydro schemes. The Ministry of Energy has also written to the Union Ministry of Coal to consider the option of open pit mines as potential sites for pumped hydro in the future.

key restrictions:

i) The main challenge is the lack of availability of natural gas to operate gas turbines to complement the growing RE capacity in the generation mix. India’s vast fleet of 200 MW series coal-fired power plants are over 25 years old, run on old technology and do not promise rock-solid reliability. Furthermore, considering that the Indian freight demand is far from saturated, there is a need to replace outdated coal-fired plants with high-efficiency supercritical coal-fired plants as an intermediate target for the full 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 performance. We must reduce the percentage of coal-fired capacity by shutting down the inefficient fleet, and yet add new flexible capacity to meet charging requirements. There should be a provision to convert coal-based capacity to a fuel mix of gas and hydrogen,” said Ravinder, former president of the Central Electricity Authority (CEA).

On the specific concerns of energy storage considering that most of the additional capacity comes from renewables, a senior government official said that one of the requirements is storage and the other is the flexibility of thermal power plants. “We have already issued a regulation that thermal power plants will be flexible by up to 55 percent. In the next phase, after three years, we have to go down to 40 percent, which means that during the day, they would run at 40 percent and increase after sunset. Now, battery storage is expensive at Rs 10 per kilowatt hour… There is a new momentum to carry out pumped hydro projects,” the official said.

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

Therefore, these projects work similar to a giant battery in that they can store energy 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. However, PSH reservoirs can have an ecological impact in the area they reach, in line with the type of problems that reservoir-based hydropower projects face.

The Central Electricity Authority, the political arm of the Union Ministry of Energy, has evaluated a requirement of 41 GW/190 GWh (gigawatt hours) of the Energy Storage System for the integration of 500 GW of electricity based on non-fossil fuels on grid by 2030. India Energy Storage Alliance, an industry alliance focused on the development of energy storage, green hydrogen and electric mobility, estimated the requirement of around 160 GWh of energy storage system by 2030 in a report titled ” Energy Storage 2030 Vision for India”.

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