New Delhi

India'srenewable power capacity has overtaken coal for the first time in years, but coal plants supplied nearly three-quarters of the extra electricity the country consumed this summer, think tank Centre for Research on Energy and Clean Air said in a report.

Renewables, excluding large hydro, reached 243 gigawatts (GW), or 44 per cent of installed capacity, by August against 231 GW (42 per cent) for coal and lignite, according to CREA's India Energy Snapshot for the July-September quarter. A year earlier, renewables held 39 per cent and coal 45 per cent.

In generation terms, the gap runs the other way. Coal and lignite produced 351 billion units (BU), about 66 per cent of the total, while renewables produced 101 BU, or 19 per cent. Coal accounted for 73 per cent of the year-on-year increase in output, compared to 27 per cent for solar and 19 per cent for wind. Falling hydropower pulled the total down by 27 percentage points.

Electricity generation rose 11 per cent from a year earlier to 536 BU, the fastest pace in the six years of second-quarter data CREA charted. Peak demand reached 270 GW on July 16, up 18 per cent from 230 GW a year earlier.

Large hydro generation fell 20 per cent, and its plant load factor, a measure of how intensively capacity is used, dropped to 50 per cent from 61 per cent. Solar's utilisation factor averaged 18.3 per cent, slightly below last year's. Coal plants ran at 68 per cent, up from 62 per cent.

Renewables did set records. Output excluding large hydro topped 100 BU for the first time, and solar hit a daily high of 705 million units on September 30. Solar generation grew 39 per cent, wind 29 per cent and nuclear 26 per cent. Combined non-fossil generation, including hydro and nuclear, reached a record 177 BU. That is about a third of total output, even though non-fossil sources make up roughly 55 per cent of installed capacity.

The reliance on coal came with a cost. Plants consumed about 79 million tonnes a month from June through September, but "coal supply did not keep pace with this high level of consumption", CREA said. Dispatches to power plants fell from 74 million tonnes in May to 66 million in August. Stocks reached 21 million tonnes on September 30, just 36 per cent of the 58-million-tonne normative requirement. By October 1, 85 plants held less than 25 per cent of their required stocks, up from 32 on August 22, which CREA said highlights "growing pressure on the coal supply chain".

India's installed capacity reached 555 GW in August, up 12 per cent on the year. Coal's share has fallen steadily from 56 per cent in 2019. Solar alone is now 168 GW, or 30 per cent of the total.

Solar and wind produce far less per installed gigawatt than coal, because they generate only when the sun shines, or the wind blows. That is why capacity share and generation share diverge.

CREA said the daily peak fell during solar hours on 62 of the quarter's 92 days, a shift that favours solar. But the evening peak is still largely met by coal. Battery storage supplied up to 5.5 GW at night peak, up from 4.1 GW the previous quarter, but that covers only about 1-2 per cent of national demand. About 9.1 gigawatt-hours of battery capacity is operational.

Grid constraints also limited how much renewable power reached consumers. About 1,835 million units of solar and wind output were curtailed in July and August alone, CREA said.