South African power utility Eskom has less than 20 days of coal supplies at 10 of its 15 coal-fired power stations, posing a threat to national power supplies. “Out of our 15 coal-fired power stations, 10 of them have less than 20 days. Clearly this is contrary to what the regulator has prescribed,” Eskom spokesman Khulu Phasiwe said yesterday. The cash-strapped firm is critical to South Africa’s economy, as it supplies more than 90 per cent of its power and is one of its most indebted companies.