Liberal Democrats have voted in favour of nuclear power at the party’s conference for the first time in their history.
Party members voted by 230 to 183 in support of nuclear power in "limited" circumstances yesterday after Energy and Climate Change Secretary Ed Davey told their conference in Glasgow it would be "reckless" to rely on coal and gas, along with renewable sources of energy.
Earlier, environmental campaigners urged the party to reject nuclear power in an effort to restore its green credibility, but the party, traditionally opposed to nuclear power, rejected an amendment to a policy motion that will dictate the Lib Dem manifesto at the 2015 general election.
But while accepting the need to build new nuclear power stations in limited circumstances, activists insisted on tougher restrictions on fracking to be introduced into Liberal Democrat policy.
Davey said: "When I have listened to pro-nuclear Liberal Democrats over the years, there is one argument I have found increasingly difficult to answer and that is the climate change argument.
"Climate change poses a real and massive danger to our planet. Not keeping a genuinely low carbon source of electricity as an option is reckless when we don't know the future.
"We are going to need vast amounts of low carbon electricity to tackle climate change. Why? Because if our carbon capture and storage plans don't work, we may have to replace all fossil fuels for electricity generation, that is about 60 per cent of all generation.
"If we do that without nuclear, you will need to replace about 85 per cent of electricity generation. That's huge."
Activists raised concerns about the cost of new nuclear power stations but Davey told the conference he would not allow the price of projects to get out of control and that he was absolutely determined not to sign any contract for new nuclear power stations which relied on public subsidy.
He added: "New nuclear must be cost-competitive. We will not repeat the history of mistakes on nuclear."
Under the motion, which was passed amended, tougher restrictions on shale-gas sites are aimed at ensuring pollution levels are properly monitored, while residents living close to fracking sites are properly consulted about plans.
Chris Davies MEP, who put forward the amendment, said: "I am not anti-shale gas development as long as controls are put in place, environmental protections are secured and the communities affected gain direct financial benefit."
Friends of the Earth's policy and campaigns director Craig Bennett said: "Backing for nuclear power punches a huge hole in the Liberal Democrats' fast-sinking green credibility.
"Nuclear power comes with massive costs attached. Ed Davey is deluded if he thinks new reactors can go ahead without public subsidy; building them will result in the Liberal Democrats, yet again, breaking their promises.
"Championing a plastic bag charge is a drop in the ocean. With its support for new reactors and gas-fired power stations and refusal to back power sector decarbonisation, the Liberal Democrats are fast becoming Tory-lite when it comes to the environment."
But Davey claimed yesterday that the Lib Dems were still the champions of green policy in Government, claiming the Conservatives have reneged on their commitment to be the greenest government ever after "relentlessly attacking" Lib Dem efforts to tackle climate change.
Davey said the Lib Dems had to fight against obstructive Conservative ministers for every energy and environment policy win they had secured since 2010, painting an image of a coalition Government torn by factional politics and competing interests.
He said: "We are the greenest party that has ever served in government. But our fight, and it is a fight, is to make the coalition the greenest government ever."
Mr Davey said while the scientific consensus "remains as solid as ever", politically, Britain had gone in reverse.
"Before the last election, this fight had seemed over; the scientific consensus had led to a political consensus. But that is being relentlessly attacked, inside and outside the coalition."
Davey used his Glasgow speech to announce a new cash incentive to build more turbines on the Scottish islands, including the Shetland, Orkney and the Western Isles.
He said he hopes the draft deal, which would be worth £115 per MWh for onshore wind, will help harness the "amazing green energy sources" on the islands. It could lead to hundreds more turbines generating an additional 400MWh for the grid.
"People have been waiting for this decision to be taken, no one has taken it before, and we are delivering it," he said. "It's going to enable them to develop these windfarms, to sell that electricity, that green energy, and they will create jobs and economic activity."
The so-called strike price of £115 is higher than the £100 proposed for the UK mainland in 2014-15, announced in June.