The electricity deficits this summer could be worse than expected, as Grid-India's shortage forecasts were made weeks before India's weather office predicted heat waves between March and May.

A rapid addition of solar farms has helped India avert daytime supply gaps, but a shortage of coal-fired and hydropower capacity risks exposing millions to widespread outages at night, government data and internal documents reviewed by Reuters show.

India faces a high risk of nighttime power cuts this summer and in coming years, as delays in adding new coal-fired and hydropower capacity could limit the country's ability to address surging electricity demand when solar energy is not available.

A rapid addition of solar farms has helped India avert daytime supply gaps, but a shortage of coal-fired and hydropower capacity risks exposing millions to widespread outages at night, government data and internal documents reviewed by Reuters show.

India's power availability in "non-solar hours" this April is expected to be 1.7% lower than peak demand - a measure of the maximum electricity requirement over any given time, an internal note by the country's grid regulator reviewed by Reuters showed.

April nighttime peak demand is expected to hit 217 gigawatts (GW), up 6.4% on the highest nighttime levels recorded in April last year.

"The situation is a little stressed," Grid Controller of India Ltd (Grid-India) said in the note dated Feb. 3.

While Indians looking to beat the heat this summer will want steady power for their air-conditioners, night time outage risks threaten industries that operate around the clock, including auto, electronics, steel bar and fertiliser manufacturing plants.

"If there is a power cut even for one minute, paper pulp gets blocked and messes up the delicate process and causes hundreds of thousands of rupees in losses," said P.G. Mukundan Nair, former chief of an Indian paper industry body who has been in paper manufacturing for nearly three decades.

"Even the smallest interruption in power supply will create havoc," Nair said.

The electricity deficits this summer could be worse than expected, as Grid-India's shortage forecasts were made weeks before India's weather office predicted heat waves between March and May.

EMERGENCY STEPS

India's federal power secretary Alok Kumar downplayed concerns, saying the government had taken "all steps" to avoid power cuts.

"We are making capacity available to all states at competitive rates," Kumar told Reuters.

After the Grid-India report, the government brought forward maintenance at some coal-fired power plants and secured extra gas-fired capacity to run to try to avert outages, another senior government official said.

As much as 189.2 GW of coal-fired capacity is expected to be available this April, according to Grid-India's February note. That would be up more than 11% from last year, according to Reuters calculations based on Grid-India data.

Together, coal, nuclear and gas capacity are expected to meet about 83% of peak demand at night.

Hydro power will be crucial not only to meet much of the remaining supply but also as a flexible generator, as coal-fired plants cannot be ramped up and down quickly to address variability in demand.

However Grid-India has forecast peak hydro availability in April this year will be 18% below what it was a year earlier, when output was boosted by favourable weather conditions.

Imported coal-based power plants would be required to crank up output to up to 55% of total potential from 21% in February, while domestic coal-fired units will have to increase output to 75% of potential from 69% in February, Hetal Gandhi, Director- Research at CRISIL Market Intelligence and Analytics said.

"The burden of increased supply will definitely be borne by coal and gas," Gandhi said, adding achieving it would be a "tall order".

MORE CAPACITY NEEDED

The nighttime outage risks are in sharp contrast to daytime. Supply in daylight hours has been bolstered by nearly four-fold growth in solar capacity over the past five years, in line with Prime Minister Narendra Modi's Paris climate agreement pledge to curb carbon emissions.

As of last April, solar boosted renewables' contribution to as much as 18% of India's generation in the middle of the day.

The strain comes after sundown, as coal-fired capacity has grown only 9% over the last five years.

Around midnight through April last year, jostling for power was intense, with buyers making bids for five times more power than sellers offered, a Reuters analysis of data from the Indian Energy Exchange, the country's most liquid electricity trading platform, showed.

The widening demand-supply fault lines highlight the need to expedite coal capacity additions to avert outages in the next few years.

Construction of as many as 26 coal-fired units with a capacity of 16.8 GW has been delayed by more than a year, data from the Central Electricity Authority shows, with some plants facing delays of more than 10 years.

Projects under construction are being stalled by local protests over environmental concerns, legal challenges over compensation for land acquisition, and availability of labour and equipment, according to officials at power plants.

Hydro and nuclear power capacity additions face tougher obstacles, as they are hobbled by lack of foreign investment and opposition from critics over safety and environmental issues, boding ill for power supply down the track.