Image caption The leaked document discusses the need to move towards renewable sources of energy

A leaked Scottish government document looking at energy policy in an independent Scotland has been seen by the BBC.

It is the second time in a year that unauthorised information has emerged from the department of Finance Secretary John Swinney.

This latest document, marked "RESTRICTED - DRAFT Scotland's Energy Future" appears to be a policy paper the Scottish government plans to release later this month.

In it, officials discuss the need to move towards renewable sources of energy and away from what they call "damaging, price volatile fossil fuels".

It claims greater acceptance of renewable energy like wind power projects in Scotland could help other parts of the UK, where it is less popular.

Little of the other detail is new.

For instance, we already know the Scottish government would like to maintain a UK-wide energy market after independence.

The document seems to confirm this. It says: "The shared regulation of a single GB-wide energy market, by the new Scottish regulator and the England and Wales regulator, presents the best approach for an independent Scotland.

"An independent Scotland will seek a new strategic energy partnership with the rest of the UK - a partnership of equals - where the UK and Scottish governments jointly steer policy towards the energy sector."

Fuel poverty

It also restates the Scottish government's preference for the current UK-wide subsidy of renewable energy to continue after independence, saying: "It is equitable that these costs continue to be shared among consumers in Scotland and the rest of the UK."

Opponents have questioned why the rest of the UK would want to do that.

The document says the case for Scotland's control over energy is "compelling", allowing ministers to better address fuel poverty. It says "independence is the opportunity to provide a clearer focus on the reduction of household and business energy bills and improving energy efficiency".

The document also claims renewable energy projects have more public support in Scotland than other parts of the UK.

"Higher levels of public acceptance of renewable energy developments in Scotland, including onshore wind, helps other parts of the UK, where public acceptance is more polarised," the document says.

"The transition to renewable energy reduces our dependence on damaging, price volatile fossil fuels, bringing greater stability in energy prices for consumers."

In March a briefing paper emerged which discussed the affordability of pensions in an independent Scotland and the potential difficulties caused by volatile oil prices.

'Private concern'

Since then pro-union campaigners have accused the SNP government of saying one thing in private but another in public.

Officials are currently working on what ministers call a "prospectus for independence", otherwise known as a white paper, setting out the main arguments they hope will deliver a Yes vote next year.

Labour's energy spokesman Tom Greatrex MP said the latest leaked paper "yet again makes public the private concern of SNP ministers about the volatility and instability of oil prices.

"The tax we get from the North Sea is so volatile that the difference between the highest and lowest years is the equivalent of Scotland's NHS budget.

"Scotland and the rest of the UK benefit from the sharing of energy resources, risks and rewards. By pooling our resources across the whole of the UK we can better manage the peaks and troughs of oil revenue.

"The single British energy market works in Scotland's best interests. Where is the sense in breaking this up only to try to put it back together again?"

A Scottish government spokeswoman said: "This is a draft paper which will inform the work of the expert commission we announced on 7 July. The commission will advise on energy regulation in an independent Scotland and its work will in turn inform the white paper on independence to be published in the autumn.

"This follows the model of the fiscal commission working group's recent paper on a macroeconomic framework.

"The paper highlights the extensive work the Scottish government has undertaken and the advanced stage we have reached in terms of progressing major issues in a key policy area."