England would struggle to hit its renewable energy targets if Scotland votes to leave the United Kingdom, the new Energy Secretary has said.
Ed Davey, who took over the post from Chris Huhne, said both countries need each other to tackle climate change, as Scotland has more renewable sources, but England has more resources to fund ongoing developments.
He also admitted he found the English debate on independence "annoying" at a Liberal Democrat conference in Inverness.
He said: "I believe renewables are a classic case of how England and Scotland need each other. Indeed, how devolution in the UK has worked and is the best future for us all.
"Meeting our renewables target of 15% of energy by 2020 for the UK is a tough task already.
"If England has to do it for itself, by itself, it will be probably be even tougher, given Scotland has relatively more renewable sources.
"Yet the economics of renewables is that Scotland needs English consumers to help pay for the renewables, as the technology develops."
Mr Davey also said the Government should push ahead with all forms of low-carbon energy - including nuclear, which is opposed by the Scottish Government - as well as taking forward new carbon capture and storage (CCS) technology.
He boasted that the Tory-Lib Dem coalition will be the "greenest government ever" and gave a warm endorsement of his predecessor's work.
"Chris achieved more in his 20 months on energy and climate change than any other British minister in the last 20 years. So I have a hard act to follow," he said.
He set out his ambition to tackle "polluting" housing stock, which he described as the oldest and least efficient in Europe.
But he warned of resistance to the wider ambitions, adding: "Make no mistake. This is so radical that it will be really difficult. The lobbying against it, the struggling to stop it, the vested interests who hate it.
"Getting the Green Deal going is and will be a major challenge. But I couldn't be more personally committed to seeing it through."
He said all energy sources should be investigated in the attempt to produce low-carbon power.
"In common parlance, when you're planning for the future, you don't put all your eggs in one basket," he added.
"By subsidising renewables we are seeing the costs of wind and solar tumble. And I am sure they will go down much more.
"And by being open to different low-carbon technologies like nuclear and CCS, we are creating the biggest technology race and competition of recent times."
He accepted there was "disappointment" that a CCS scheme did not proceed at Longannet power station in Fife, but said the money is available for future plans.
"As we approach the revised competition for CCS, which I hope to announce later this spring, I hope Scottish projects like Peterhead will come forward to compete," he said.
"CCS is a huge investment even for a large economy like the UK's. In these difficult times, to put £1 billion into a competition for such a development shows we are serious. The UK Government has found the cash and we will proceed with CCS."
Mr Davey also highlighted the benefits of the new UK Green Investment Bank, which is designed to generate investment for green energy projects.
A decision on the location of its headquarters is expected within the next few days, with Edinburgh and London considered to be among the strongest candidates.
However, former Liberal Democrat leader Charles Kennedy later suggested England may need a second Green Investment Bank if Edinburgh wins the bid for its UK headquarters and then subsequently becomes the capital of an independent Scotland.
Mr Kennedy, who described himself as the Lib Dem "point man" in the anti-independence campaign, said he doubted that Westminster would withdraw the bank from Edinburgh post-independence.
However, he added: "It would depend, if you were independent, I suppose, what a government in London governing England would do.
"Would they want to have their own Green Investment Bank, and leave us with whatever was left?
"I think this is where all of these arguments really begin to unravel because there aren't clear answers to any of this from the pro-independence lobby, and these are the kind of questions that we will be putting to them with increasing rigour over the coming months."
Yesterday, Business Secretary Vince Cable said the future of all UK institutions in Scotland "would be questioned" if the country becomes independent.