Scotland would refuse to pay for all the decommissioning costs of nuclear power plants on its soil if it were to win independence from the rest of the UK.

Instead it would only pay a percentage based on the remaining life of reactors after a spilt from the UK.

And the government in Edinburgh would apply that same rule to the decommissioning of oil and gas assets in what would become its share of the North Sea.

That was the viewpoint spelt out by Scotland’s energy minister Fergus Ewing, when he gave evidence to an inquiry into Scottish independence held by the UK government’s Energy and Climate Change Committee.

Scotland, which has had a devolved parliament since 1999, is pushing for independence from England, Wales and Northern Ireland under its ruling Scottish National Party (SNP).

If this were to happen, the division of energy infrastructure – and the distribution of the power it creates – would become one of the hot topics to be discussed between politicians in London and Edinburgh.

More than half of the UK nuclear fleet is based in Scotland, as is the vast majority of Britain’s existing and potential wind and wave power. And as Ewing acknowledged, “the lion’s share of remaining oil and gas would accrue to Scotland as they fell within Scotland’s international waters”, which in turn would make Scotland “an exceptionally wealthy country”.

However, when asked if Scotland would take on the decommissioning costs for the nuclear reactors lying within its borders, Ewing said: “We take the view that these nuclear power plants were set up by the UK and therefore, if we take for example Torness (commissioned in 1988 and due for decommissioning in 2023), if there are 10 years to go and 30 years have elapsed, then we have one quarter of the decommissioning costs. Some apportionment of that sort would seem to me to be reasonable.”

He applied the same rule of thumb to the decommissioning of oil and gas rigs in the North Sea, having already conceded that “the value of Scotland’s oil and gas reserves are absolutely extraordinary”.

The committee chairman Tim Yeo asked Ewing if he agreed that the drive towards independence by the SNP “has had the unfortunate consequence of creating a degree of uncertainty [among investors], and an industry like energy depends entirely on investors making very long term decisions?”

However, Ewing was emphatic: “No I don’t agree with that. Ever since last May there has been very substantial investment in the Scottish energy sector and these decisions show that there is not a lack of confidence in Scotland.”

To stress his point he named a list of companies which have taken key strategic decisions to locate in Scotland: Gamesa spending £125m to build a base in Leith rather than in Hartlepool in England; Samsung setting up in Fife with an investment of another £125m; and Global Energy in Nigg, creating “up to 2000 jobs first in oil and gas and then in renewables”.

“Would these decisions have been made if the world was afraid of coming to Scotland? I don’t think so,” he said.

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