Octopus Energy has called for customer flexibility to be a permanent solution for balancing the energy system and an end to the reliance on back-up coal generators. It comes after Uniper was instructed to fire up two back-up coal-fired power units this week to cope with additional electricity demand during the ongoing heatwave. Octopus claims that making the service available to all 17.3 million UK homes with smart meters would be enough to entirely replace coal as a back-up source of power.