David Prosser's Outlook: The lights may be going out but power cuts provide an ugly vision of Britain's future

Half a million people hit by power cuts on Tuesday may just have had a sneak preview of what the future holds.

Environmentalists yesterday seized on the blackouts as evidence of Britain's over-dependence on a handful of ageing power plants, while electricity producers claimed a series of unfortunate coincidences were to blame. Either way, if you got stuck in a lift in Cheshire, lost power at home in South London, or had an operation cancelled at a hospital in High Wycombe, you were the victim of an energy gap, a failure of supply to meet demand.

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This shortfall was a one-off, but the UK continues to sail towards a moment, seven or eight years from now, when the energy gap becomes a much more permanent reality. Despite more than 15 years of warnings that Britain must replace its ageing power stations within the next decade in order to bridge this gap, little has been achieved. Gordon Brown is now more convinced than ever that nuclear energy is the answer to the UK's power problem, indicating yesterday that he now expects to see the construction of new plants over the next 15 years as well as replacements for existing facilities, all but one of which will be decommissioned by 2023.

However, leaving aside the small matter of the huge political and environmental controversy that surrounds betting on nuclear, the Prime Minister has yet to explain how these new nuclear power stations will come into existence, having ruled out any public subsidy for their substantial construction costs.

The good news for would-be builders of the next generation of power stations is that planning laws have been streamlined to make it easier to get permission for construction. Even so, the 14 sites, owned by British Energy, where nuclear power stations are currently in operation, clearly hold the key.

That makes the question marks still dogging the future ownership of the company all the more a cause for concern. Three bidders, all foreign-controlled, are still thought to be in the running to buy up the company. If one of them is allowed to walk off with the prize, the UK's nuclear future would hang on the whims of a single power giant – not even a British company.

Talks over its future are continuing, British Energy said yesterday, but Centrica, the only British company with an interest in the deal, is currently pinning its hopes on some sort of agreement with one of the foreign buyers.

Still, the delicate issue of finding sites for all these new nuclear plants is straightforward compared to the question of whether anyone can be persuaded to build them. Mr Brown says there will be no limit set on how much electricity the UK can source from nuclear plants, but nor will there be any minimum contribution from the sector.

Put another way, despite the huge costs involved in building new nuclear plants, there is no guarantee operators will be able to sell the power produced. One advantage of nuclear is that running and fuel costs are relatively low compared with gas and coal-fired stations, were costs fluctuate in line with global commodity prices. Even after taking into account substantial construction costs, nuclear power looks cheap at today's oil price – but there is, of course, no certainty about what that price will be by the time plants are finally built.

Just to add to the headache, there's the rather inconvenient question of waste, where the Government still has not worked out where the most dangerous material might be stored. There has been some vague talk of an interim facility for holding waste until a suitable underground site for the longer term has been found. The talk on the detail of the latter, particularly who might pay for its development, has been even vaguer.

All in all, it is difficult to imagine work starting on large numbers of nuclear power plants any time soon. That will no doubt delight anti-nuclear campaigners, but there is little prospect of renewable energy (or even planned new coal-fired power stations) plugging the gap Mr Brown claims nuclear will fill. And it won't be long before that means more regular blackouts.