The Tory leadership frontrunner has promised to lift a moratorium on the controversial technology as part of a bid to improve the security of the UK’s energy supplies after a dramatic rise in gas prices triggered by Russia’s invasion of Ukraine. But in his final policy speech before leaving Downing Street on Tuesday, Mr Johnson said he was “doubtful” that fracking would be a “panacea” and warned the new prime minister not to “put all our eggs in that one basket ». He urged his successor to continue his plans for eight nuclear reactors and major investment in offshore wind power. The green light for Sizewell C came as the International Monetary Fund (IMF) warned that rising energy prices were hitting UK household budgets harder than any other country in western Europe. The average UK household will lose 8.3% of its total power on energy bills this year, compared with 4% in Germany or Spain, the world economic body found, which blamed Britain’s unusually high reliance on natural gas for domestic heating and electricity generation. . And the impact of higher prices is “particularly skewed” in the UK towards poorer households, said the IMF’s Oya Celasun. The poorest 10 per cent of UK households are expected to spend 17.8 per cent of their budget on energy in 2022, compared to just 6.1 per cent for the richest 10 per cent. The gap of 11.7 percentage points far exceeds the gap of 3.9 points between rich and poor for France and 2.5 points for the Netherlands. An alliance of 48 charities has sent an open letter warning of a “tsunami of need” caused by the cost of living crisis and calling on ministers to provide “urgent and substantial” financial support to the most vulnerable. Charity bosses said a “financial crisis of a magnitude not seen for decades” would push many who have previously managed to get by into poverty and plunge those currently struggling into “desperation”. “We call on the government to urgently provide substantial financial support to those most in need, directly to households and through the benefit systems already in place to provide support,” they said. Mr Johnson said he was confident the new prime minister taking office on Tuesday would deliver “significant sums” to support those affected by the energy crisis caused by Putin’s “kamikaze attack” on the global economy. “Of course, there will be more cash for whoever takes over from me in the coming months – significant amounts, that’s absolutely clear,” said the Prime Minister, who was mocked for suggesting people should invest £20 in a new kettle to save £ 10 a year in accounts. But there were no further details from leadership candidates Rishi Sunak or Liz Truss on either package, although front-runner Ms Truss promised immediate and “robust” help for those facing unaffordable bills. Chancellor Nadhim Zahawi confirmed that the finance ministry is working on options for the incoming Prime Minister, which would include an industrial plan for a government fund to compensate companies for holding domestic bills, currently expected to average £3,549 in October. Ms Truss spoke during the leadership election campaign against rural solar farms and said she would allow fracking where it was supported by local communities. But Mr Johnson insisted that renewables, along with nuclear, were key to solving the UK’s dependence on imported fossil fuels. “I say to everybody who thinks that hydrocarbons are the only answer and that we should have fracking and all that: offshore wind is now the cheapest form of electricity in this country,” he said. “Offshore wind is nine times cheaper than natural gas.” He said government cash for Sizewell would allow developers EDF to get the project “over the line” in the coming weeks, although the final green light would be a matter for his successor next year. Britain’s failure to build new plants since 1995 meant the UK only gets 15% of its electricity from nuclear, compared with 70% in France, he said. But the prime minister fell short as he tried to blame delays in replacing the UK’s aging nuclear power network on the “short-sightedness” of previous Labor governments. Ed Miliband pointed out that Tory-led administrations had failed to progress in 10 sites since the go-ahead under Gordon Brown in 2009. Unions said government support for the £30bn 3.2 gigawatt plant should have been handed over long ago for the sake of jobs and energy security. Unite’s energy manager Simon Coop said: “Even today, there is no guarantee that this project will go ahead in 2023 because Boris Johnson’s decision will have to be ratified by the next prime minister. “Where we needed certainty and a clear roadmap for energy security, we got more waffle, more hollow words from Boris Johnson.” And GMB national secretary Andy Prendergast said: “Today’s decision is an overdue step in the right direction – but it should have happened years ago.” Mr Johnson was welcomed to the Sizewell site by protesters opposing the disruption and environmental damage they expect from the massive construction project. The group Together Against Sizewell C (TASC) has launched legal proceedings over what its lawyers claim are “fundamental legal errors … in relation to water, alternatives to nuclear power, local wildlife and climate change” in the decision for granting approval. Greenpeace UK chief scientist Doug Parr said the £700m announced for Sizewell C would do nothing to reduce energy bills this winter and would be better spent on clean renewables “rather than being thrown into the slow economic fire that is EDF”. But the chief executive of the Nuclear Industry Association, Tom Greatrex, welcomed the funding pledge, saying it would help “reduce gas, lower bills and create stable, secure well-paid jobs for people up and down the country”.