Could be that when a power line goes down (chute de ligne, not necessarily literally a collapsed transmission line) and the power produced cannot be supplied to the regular loads, which causes problems for the power produces (see recent massive outages in teh USA/Canada and Italy), the steel mills are ready to switch over (instantly?) to electric power which, given that they are saving the producers embarrassment and wastage, they can purchase at cheap rates, until such time as the network is restored.