After a weak monsoon curtailed hydro generation and forced the country to rely heavily on coal-fired generation in the summer and autumn of 2023, fuel inventories fell to critically low levels in October.
But they recovered strongly in November, December and January, with record volumes of coal dug and despatched by rail to generators over the last three months.
Plentiful stocks of coal at power plants should minimise the risk of blackouts during the difficult spring period even if temperatures are hotter than usual in March and April.
Chartbook: India coal and power, opens new tabGenerators are currently storing 38 million tonnes of coal on site, up from 33 million tonnes at the same point in 2023 and 25 million tonnes in 2022, according to data from the Central Electricity Authority.
Fuel inventories are sufficient to cover almost 14 days of generators' minimum requirements up from 12 days in 2023 and nine days in 2022.
The more comfortable fuel situation is partly the result of a determined effort to boost coal production and ensure coal deliveries are prioritised on the railway network.
The country's mines raised production by 106 million metric tons (12%) and the volume delivered to generators increased by 50 million tons (7%) in 2023 compared with 2022.
The number of unit coal trains despatched to power producers averaged 279 per day in December 2023, a new monthly record and up from 269 per day in December 2022.
As a result, coal-fired power plants were able to generate an extra 11 billion kilowatt-hours (6%) in November-December compared with the same period in 2022 while still accumulating fuel.
PRE-MONSOON READINESS
India's electricity consumption peaks between June and August, when temperatures are hottest and the demand for air-conditioning and refrigeration is greatest.
But the summer monsoon is also when generation from hydroelectric sources and wind farms is greatest, relieving some of the pressure on the electricity transmission network.
As a result, power supplies tend to be most stretched in March and April, before the monsoon arrives, when temperatures and air-conditioning have started to rise but renewable generation is still low.
The same problem occurs in reverse after the monsoon in September and October, when renewable generation starts to fade while air-conditioning demand is still elevated.
The pre- and post-monsoon shoulder seasons are therefore when electricity supplies are under most pressure and the system relies heavily on extra generation from coal-fired units.
In contrast to North America and Europe where the greatest risk of blackouts occurs at the height of summer or the depths of winter, India's greatest reliability challenge occurs in spring and autumn.
The country needs to accumulate coal inventories during the summer wet season and especially in winter to ensure coal units can maximise generation during the shoulder seasons.
In September-October 2021 and again in March-April 2022 the grid was hit by widespread outages when coal generators ran out of fuel and could not start up during periods of hot weather.
Insufficient generation caused the grid's frequency to drop far below its minimum operating target of 49.9 cycles per second for prolonged periods.
Frequency fell below target 11% of the time in October 2021 and 32% of the time in April 2022 as generators could not keep up with load in hot weather.
Many generators ran out of coal and were unable to fire up when instructed by the grid. Accumulating coal inventories has therefore been a priority for the government and generators to avoid any repeat.
Stock building so far this winter has put the system in a much more resilient position to cope with the pre-monsoon increase in demand.
RENEWABLES DEPLOYMENT
In addition to boosting coal mining, India has been able to relieve some of the pressure on coal supplies through a massive expansion of renewable generation, saving significant quantities of fuel.
The country has installed 79 gigawatts (GW) of additional generating capacity since the end of 2018, with capacity increasing at a compound rate of 4% per year.
But just 10 GW of extra capacity has been coal-fired (an average increase of just 1% per year) with 60 GW coming from renewables (a compound increase of 13% per year).
Solar capacity has surged by 48 GW (24% per year) with smaller increase in wind capacity of 10 GW (5% per year), according to Central Electricity Authority data.
Solar and wind generation are intermittent so they are not a perfect match for the rapidly increasing air-conditioning, refrigeration and industrial load.
Wind speeds are variable and increased reliance on solar has created shortages in the evening when cooling loads are still high but solar output has faded with sunset.
But by easing some of the pressure on coal-fired generators at least some of the time it has enabled stock building and reduced the threat of fuel shortages and blackouts.
