One of Europe’s leading energy consultancies has estimated that Tesla’s electric haulage truck will require the same energy as up to 4,000 homes to recharge, calculations that raise questions about the project’s viability. The US electric carmaker unveiled a battery-powered lorry earlier this month, promising haulage drivers they could add 400 miles of charge in as little as 30 minutes using a new “mega-charger” to be made by the company. John Feddersen, chief executive of Aurora Energy Research, a consultancy set up in 2013 by a group of Oxford University professors, said the power required for the megacharger to fill a battery in that amount of time would be 1,600 kilowatts. That is the equivalent of providing 3,000-4,000 “average” houses, he told a London conference last week, ten times as powerful as Tesla’s current network of “superchargers” for its electric cars. Tesla declined to comment on the calculations. Elon Musk, Tesla’s chief executive, has previously said the megachargers would be solar-powered but the company has not confirmed whether they will also have a grid connection for when it is not sunny. Many of Tesla’s current superchargers are powered in part by renewable energy. The company is also experimenting with storage batteries to ease demands on the grid.