People might be forgiven for thinking that the debate on what separation for Scotland would mean is all about complicated constitutional issues and legal technicalities.

That's certainly what Alex Salmond would like people to think. He's obsessed with independence and what it means for his place in history. Unsurprisingly, for the Scots I met earlier this week on a visit to Edinburgh and Glasgow, satisfying the First Minister's ego was not their number one priority.

While he is spending hundreds of thousands of pounds of Scots' money on billboards, advertising agencies and spin doctors, the people I met were turning down their central heating or wondering how they pay their energy bills.

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For families in Scotland, and everywhere in Britain, Labour would freeze energy bills for 20 months and undertake the biggest reform of the energy market since privatisation to stop you being overcharged again in the future. But given the Nationalists have formed an unholy alliance with the Tories and the big energy companies and opposed our plans, if Scotland broke away from the rest of the UK, while bills stabilised elsewhere, they'd carry on rising inexorably north of the Border. Worse still, the investment in clean energy that has created so many new jobs, as well as supported existing industries, would grind to a halt too.

Scotland has immense renewable energy potential and the best, most effective way of unlocking that potential is through the economies of scale that come within a single, shared, British energy market. About one-third of total British investment in renewable energy comes to Scotland.

But Scottish consumers contribute less than one-tenth of the cost of the support for clean energy. By sharing Scotland's resources among 27 million households across Britain, Scotland can spread the costs and share the rewards of investing in renewable energy. Not only does Scotland benefit from this significant investment and the green jobs it brings; everybody across Britain benefits from the power generated here and protection from the price fluctuations of volatile fossil fuels such as oil. Also, this helps Britain reduce its carbon emissions.

The SNP like to tell people that things would carry on as normal, even if Scotland walked away from the continuing UK. Of course, I can't make decisions today about what might happen years from now in a world in which Scotland has exited the UK. But, in all honesty, if Scotland votes to leave the UK and I am Energy Secretary after the next General Election, I can't see why consumers in England and Wales would carry on subsidising investment in what would be a foreign country.

England and Wales already have interconnectors bringing in electricity from France and the Netherlands, with plans for more connections with countries such as Belgium and Norway, and Scotland would have to compete with all these other countries if it wanted to export its energy to the rest of Britain.

Likewise, the costs of decommissioning the North Sea oil and gas installations would place a massive burden on an independent Scotland, and vital new technological innovations such as carbon capture and storage would be in doubt if Scotland couldn't share the start-up costs with the rest of Britain.

The truth, of course, is that the strength of the Scottish energy sector is sustained by its consumer base across Britain. As part of a larger, stronger home energy market, people in Scotland benefit from lower energy bills and the creation of more green jobs.

Independence would mean losing the British renewable subsidy, threatening investment and raising the cost to consumers or taxpayers. A report by Citigroup warned that, if the burden of investing in renewables fell on Scottish consumers alone, this could increase household energy bills by £875 a year. Everyone would be the poorer if the nations of the UK went their separate ways.