India is grappling with an escalating crisis as stockpiles of coal — the fuel used to generate about 70% of the nation’s electricity — dwindle to the lowest in years just as power demand is set to surge.

Coal-fired power stations have an average of four days’ worth of stock of the fuel, according to the latest data, and more than half the plants are already on alert for outages. Power Minister Raj Kumar Singh has warned that the nation could be handling a supply squeeze for as long as six months.

Power shortages are already emerging, and the gap between available electricity supply and peak demand widened to more than 4 gigawatts on Monday, according to government data from power ministry.