India’s electricity transmission system smashed previous records for generation and consumption in August, according to the latest monthly data from the Grid Controller of India.

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Nonetheless, network stability improved as surging output from coal-fired generators made up for a shortfall from hydroelectric sources impacted by a patchy monsoon.

As in China, the system’s performance highlights the inconvenient truth: coal is still the marginal fuel keeping the lights on despite the rapid deployment of renewables.

Total electricity consumption for the month climbed to a record 152 billion kilowatt-hours (kWh), blasting past the previous record of 140 billion kWh in June, and up from just 130 billion kWh in the same month a year earlier.

The system set a new record for simultaneous load served of 237 gigawatts (GW), up from the previous record of 223 GW in June and just 195 GW in August 2022.

Total generation from all sources increased by 21 billion kWh (+16 per cent) compared with the same month in 2022. (“Operational performance report”, Grid India, September 25).

Most of the extra generation came from coal-fired units (+16 billion kWh), with smaller contributions from wind farms (+3 billion kWh), solar power (+2 billion kWh) and gas (+2 billion kWh).

Hydro generation fell slightly (-1 billion kWh), owing to patchy monsoon rainfall and depleted reservoirs, and met just 16 per cent of total demand compared with 19 per cent the year before.

IMPROVED RELIABILITY

The transmission system served record load while avoiding the severe instability and widespread blackouts that occurred in 2021 and 2022.

Power grid frequency is a common proxy for the reliability of the network, with under-frequency signalling insufficient generation while over-frequency signals too much generation to match the load on the system.

Frequency slumped significantly between Aug. 29 and Sept. 1 - a sign generators were unable to meet record peak demand in full.

Frequency averaged just 49.94 to 49.96 cycles per second (Hertz) compared with a target of 50.00 throughout the four-day period.

It fell below the minimum acceptable threshold of 49.90 Hertz for as much as 25 per cent of the time on the worst affected days.

For the month as whole, however, the system was more stable, with fewer, shorter and less severe periods of under-frequency.

Frequency fell below the minimum acceptable threshold just 7 per cent of the time compared with 9 per cent the same month a year earlier.

COAL-FIRED GENERATION

The grid boosted coal-fired generation to a near-record 104 billion kWh in August.

Improved fuel availability ensured coal-fired units were able to start up when called on – averting the severe power shortages and blackouts that plagued the network in October 2021 and again in April 2022.

To ensure sufficient fuel on hand, India’s domestic mines boosted coal production by almost 65 million tonnes (+11 per cent) in the first eight months of 2023 compared with the same period in 2022.

And the rail network hauled an extra 24 million tonnes (+5 per cent) to power producers over the same period, according to the Ministry of Coal.

India’s railways despatched an average of 248 coal trains to generators every day in August 2023, up from 233 in August 2022 and 211 in August 2021.

As a result, generators still held inventories equivalent to nine days of consumption near the end of September 2023, down slightly from the same month in 2022 but well above the four days in 2021 that precipitated a power crisis.

In the long term, the rapid growth in renewable generation will curtail the need for so much coal combustion, but any peak in coal is still several years in the future.