Britain's National Audit Office (NAO) has warned that consumers could face energy bill increases of up to £7.8 billion a year by 2030 if a sweeping overhaul of the country's electricity grid does not proceed quickly enough. The £70 billion programme — aimed at modernising pylons, overhead lines, and substations to carry power from wind and solar farms — has so far completed just 16 of the 80 projects deemed necessary, with most still in early stages. The NAO cautioned that the required pace of delivery would be "very challenging," and called on the government, regulator Ofgem, and the National Energy System Operator to publish clearer data on costs and progress so that the public can hold them to account.