According to the Trade and Industry Secretary, Alan Johnson, it is now "decision time" on nuclear power. But - in reality - that time has been and gone. And it looks worryingly like the wrong decision has been made. A White Paper on energy published in February 2003 argued that Britain's existing nuclear power stations should be allowed to lapse into obsolescence, and recommended that our future needs should be met by a massive expansion of renewable energies. The report was warmly welcomed by the Prime Minister, who strongly indicated that he would not allow more nuclear power stations to be built in Britain.

So what was the Government doing yesterday launching a three-month public consultation over nuclear power? Why did Mr Johnson ask the Health and Safety Executive to look at the cost and suitability of replacing existing nuclear plants? The answer is that the Prime Minister has changed his mind. He now believes the future for Britain's energy needs is nuclear after all. Yesterday's consultation is simply the final stage of a public relations exercise designed to prepare the ground for a Prime Ministerial volte face on nuclear energy. It is a classic New Labour spin operation.

We do not doubt that Mr Blair has come round to nuclear energy for honourable reasons. The UK is struggling to reduce its carbon emissions. And nuclear power looks - superficially - like one way of achieving that. The Prime Minister also probably has an eye on the long-term security of the UK's energy supplies. With North Sea oil and gas reserves on the verge of running out, Britain will soon be importing up to 80 per cent of our energy. Given the present uncertainty of the supply of gas from Russia and political instability in the Middle East, it seems wise to cultivate another domestic supply.

But building more nuclear power stations is not the answer. The dangers are too great. This is not just because of the risk of accidents, although Chernobyl and Three Mile Island still loom large in the memory. There are clear links between civil and military nuclear programmes. This was North Korea's route to nuclear weapons. If Britain decides to build more nuclear power stations, what moral right will we have to argue that a nation like Iran should not do the same? We must also consider the immense dangers posed by nuclear power's environmental legacy. Radioactive by-products of the fission process must be buried and safeguarded for thousands of years. Nuclear power is also immensely bad value for money. It has always required hefty Government subsidies. There are huge costs in the construction and decommissioning of nuclear plants. Their insurance premiums are also prohibitive.

Opponents of nuclear power must, of course, be wary of coming across as stubbornly rejectionist when it comes to the debate about how to meet Britain's future energy needs. Clean and safe methods of dealing with this problem do exist. Renewable energies like wave and wind power have not yet been properly exploited. And energy conservation could reduce demand significantly. This would require better insulation of houses and offices. It would mean government inducements for people to switch off their lights and demands that producers make their electronic appliances less wasteful. One suspects that the reason we hear so little about such measures from the Government is that they do not have the allure of a grand projet like expanding nuclear energy.

But Britain does not need more nuclear power stations. We need a government that is prepared to engage in the difficult work of tapping greener sources of power and reducing our inexcusable wastage of energy.