Environmental campaigners today stepped up the pressure on Energy Secretary Ed Davey calling on him to step down if the forthcoming Energy Bill did not include a legally-binding target to decarbonise the power sector by 2030.
Mr Davey told Liberal Democrat members in his speech at their party conference in Brighton that there was a "strong case" for a carbon limit for Britain's energy grid for 2030.
Friends of the Earth's Executive Director Andy Atkins signalled activists would be watching to see if Mr Davey stood by his word.
Mr Atkins said: "Delivering a carbon-free electricity system is the acid test of Ed Davey's term in office - if the Energy Bill doesn't include a legally-binding target to decarbonise the power sector by 2030, he should resign.
"Investing in the UK's huge clean energy potential is essential to power a strong, modern economy and create hundreds of thousands of new jobs.
"Warm words are not enough - Davey must stand up to the anti-green Chancellor and a reckless dash for gas that will scupper our climate change targets and lock the economy into spiralling fuel bills for generations to come."
During his conference speech, Mr Davey underlined his determination to stand up Chancellor George Osborne and Tory doubters, declaring: "I have no time for the sceptics who say we can't afford green investment."
Mr Davey said that opponents were putting at risk the growth equivalent of building 20 Olympic stadiums every year until 2020 and billions in private investment that would cover the "vast bulk" of the costs.
He added that many projects were the sort of "shovel ready" investments sought by the Treasury.
"How can the critics ignore this? Why won't they champion this British growth opportunity? How can they let ideology blind them to what is happening right before their eyes?
And he turned the group name adopted by staunch Thatcherites back on them in a pointed dig, declaring: "My message to them is simple: "No turning back from tackling climate change. No turning back from green jobs. No turning back from green growth."
"Conference, the Liberal Democrats are not for turning."
Mr Davey underlined that investors craved certainty and stability and confidence that "Governments will stick to their word".
He said: "That's why the Climate Change Act was so important. That's why there's a strong case for a carbon limit for Britain's energy grid for 2030."
Mr Davey emphasised his job was "fighting for greener growth".
He added: "Our coalition agreement to clear up Britain's mess wasn't an agreement to turn the clock back. For business as usual. To rekindle Thatcherism - or Blair-Brown. It was for a fairer, greener Britain - and we must fight for that."
To restore investor confidence he wants to include a commitment in the Energy Bill to a 2030 target for reducing emissions from the energy sector - with the exact figure placed in secondary legislation to allow flexibility.
Mr Davey also unveiled a £5 million fund for schemes bringing together local people to switch energy supplier en masse in a bid to secure lower bills.
The cash will go to the best initiatives drawn up by local councils and community groups, with Mr Davey warning that without them the best deals were reserved for "well-heeled internet savvy" consumers.
He was inspired to offer the funding after being present at the launch of such a move in Cornwall - set up jointly by a local authority, the NHS, a trade union, the Eden Project and a brewery.
And the Department for Energy and Climate Change (DECC) said he was now "putting booster rockets on the concept".
Mr Davey told the conference that it will form part of a "community energy revolution" including action to promote German-style tough renewable targets and co-operatives.
He also confirmed that the Government was pushing ahead with proposals - put out for consultation in April - to give regulator Ofgem new powers to force energy companies to compensate customers for mis-selling and overcharging.
Currently energy suppliers voluntarily give cash to consumers following errors - but there is no obligation - while Ofgem has been able to fine companies, but that money has gone to the Government.
He added he would work with Communities and Local Government Minister Don Foster to look at council tax discounts for energy efficiency to see if they would encourage people to sign up to the Green Deal.
The party's conference earlier called on the Government to push other European countries to adopt a target to reduce emissions by 30% by 2020.
The motion also called for reform of the European emissions trading scheme, action to phase out hydrofluorocarbons (HFCs) - the fastest growing category of greenhouse gases and work to secure progress on a legally binding international climate change agreement.
Mr Davey said: "Moving to 30% would be an act of climate statesmanship, one that speaks to Europe's reason for being. Collective action for the betterment of our citizens."
Lib Dem MP Martin Horwood, co-chairman of the party's international affairs backbench committee, said some Tories "still don't get it".
He said: "The climate science has got more convincing and more worrying, the evidence clearer and clearer and the warnings about the economic impact of climate change have got more and more dire.
"And yet still they think we can't afford to go green."
In a message to Chancellor George Osborne he said: "The truth, George, is that we can't afford not to."
He also railed against Conservative eurosceptics: "While whiny Tories whinge about Johnny Foreigner and witter on about dots and commas in European treaties, the world must move on."