He confirmed Peterhead as the location for the world’s first gas-fired carbon capture and storage (CCS) facility as part of a £100 million Government investment in the new technology.
Harmful carbon dioxide emissions would be buried under the North Sea in the project, which goes alongside previously-announced plans for a coal-fired version in Yorkshire.
But Mr Davey said an independent Scotland would find it “more difficult to proceed” with the project.
Outside of the UK, future variations in oil and gas prices would also leave Scotland’s finances “very seriously” exposed as measures were set out to better exploit remaining North Sea reserves, he predicted.
Denying it was a bribe to Scots to vote “no” in September, Mr Davey told the BBC Radio 4 Today programme: “That’s not what I am saying.
“I am in charge of UK energy and climate change policy. We are not preparing for independence; we are pursuing our policies as if the UK is going to stay together.
“And with the UK staying together, we need to tackle climate change, we need to invest in low-carbon projects.
“It is just a fact that if Scotland was to vote for independence... it would be more difficult because it would be more expensive.”
Speaking ahead of a meeting of the UK Cabinet in Aberdeen as the referendum debate switched focus to energy, Mr Davey said a review into better exploiting North Sea oil and gas reserves “does play into the independence debate”.
“Scotland would be very reliant on oil and gas revenue and, with the oil price being so volatile, with decline in North Sea revenues, I think that would expose the finances, the public spending of Scotland very seriously,” he said.
“What we are showing today in the Wood Review is that Westminster will manage the oil and gas reserves that the UK has in a far more effective way and that’s great for Scotland.
“Scotland has benefited from North Sea oil, let’s be clear about this. It is the third booming region in the UK. After London and the South East, Scotland is doing incredibly well, as part of the UK.”