WE ALL KNOW what Tony Blair thinks about nuclear energy. We even know what Gordon Brown thinks now. Both men seem to see support for new nuclear power stations as a sign of their political virility and their commitment to modernity.

What is far more interesting, though, is how the Conservatives will respond to the Government’s energy review, due to be published in about three weeks’ time. Will they continue with their traditional gung-ho support for nuclear power? Will they reluctantly champion the building of new nuclear stations as a way of reducing carbon emissions? Or will they use this as a powerful opportunity to make voters think about them anew, and reinforce their green credentials?

Although the line has not been finally resolved, there is strong support for the last option. Both Alan Duncan, the Shadow Energy Secretary, and Peter Ainsworth, the Shadow Environment Secretary, are diehard greens. Neither has much enthusiasm for nuclear power. And they certainly don’t hold with the simplistic argument that Mr Blair keeps using: our oil is running out, renewables can’t fill the gap, we don’t want to rely on the Russians for gas, so it’s got to be nuclear.

Actually, say the greener Tories, it’s far more complicated than that. For a start, nuclear contributes only 3.6 per cent of our total energy. The so-called energy review is in fact a review only of electricity generation, and does not address the two thirds of our energy needs that go towards heating and transport. We can’t run our cars or heat our houses with nuclear energy.

So if we want to cut our carbon emissions significantly, building new nuclear power stations won’t help much. The Sustainable Development Commission has calculated that building ten new nuclear reactors would cut CO2 emissions by only 4 per cent.

Other innovations could do far more than that. Our huge power stations — whether fuelled by coal, gas or nuclear — are grossly inefficient: they waste two thirds of the energy that they produce. Most of it rises into the air in the form of heat from the cooling towers. If Britain were to adopt a decentralised form of electricity generation, with much smaller combined heat and power (CHP) stations located in the communities they serve, then the heat produced by the stations could be channelled straight into factories and homes through hot water pipes. These CHP stations waste only 5-10 per cent of their energy.

It can be done. The whole of Rotterdam runs on decentralised energy. So does more than half of Denmark. Closer to home, Woking has set up a local network that, together with energy efficiency measures, has cut emissions by a whopping 77 per cent. That puts nuclear savings in the shade.

Decentralised energy is much cleaner than the current system and it improves energy security, because we don’t need to import so much gas.

Then, say the Tories, there are promising new technologies coming on stream. Carbon capture could make coal and gas-fired power stations much less polluting. There is huge potential in tidal power, which is more predictable than that of wind or sun. Add to that the possibility of geothermal power and hydrogen cells, and we look to be on the brink of a revolution in renewable energy, which produces no CO2 and is not reliant on imports and the whim of Russia.

Meanwhile, there is a lot of scope for reducing demand for energy. At the moment, 13 per cent of the energy that comes into our businesses and homes is wasted. As the Government’s last energy review, only three years ago, pointed out, much of the energy gap can be filled by greater efficiency. And the public have become much more receptive in the past few years. People are keener now to lead environmentally responsible lives.

Some Tories close to Mr Cameron are less instinctively anti-nuclear, but even they say that nuclear power has to prove itself in the marketplace. They don’t believe that politicians should decree what proportion of electricity generation should be made up by each fuel. They think that the Government should just set the criteria that electricity generation has to meet — say, energy security and low carbon emissions — and then each fuel will have to show its worth against those criteria. The trouble is, it is hard to account for the peculiar problems of nuclear energy: the toxicity of its waste, its vulnerability to terrorism and the costs of decommissioning.

If the Tory leadership does come up with a non-nuclear policy, it is surprisingly relaxed about getting it past the parliamentary party. Yes, many Tory MPs have always considered themselves pro-nuclear. “But what do they know?” asks a shadow minister. “Have they really thought about the issue?” Another says blithely, “We’ll cross that bridge when we come to it.”

The Liberal Democrats are still the only party that is unequivocally anti-nuclear. Its environment spokesman, Chris Huhne, makes a powerful economic case against building new nuclear power stations. The Tories are likely to be more subdued, even if they do end up on the same side. As one of them said to me yesterday: “If you can fill the energy gap without needing nuclear power, why not?”

Labour will certainly be alone in making a strong case for new nuclear stations. And the irony is that, while Mr Blair and Mr Brown think that this is the modern thing to do, they are in fact facing opposition parties with much more forward-thinking policies.

The Prime Minister and the Chancellor grew up in a 1980s Labour Party in which those who were anti-nuclear power were also anti-nuclear weapons. It was a sign of ideological purity to oppose both. Mr Blair was right to support Britain’s nuclear deterrent then. But he is wrong now to couple it with the debate about Britain’s energy needs. There are much cleaner, cheaper and safer ways to generate electricity than by building new nuclear power stations. To believe that is not to be a dinosaur, but a moderniser.

Times Recommends

• In the real world, the public sector must pay
• Playing politics in a land of double Dutch
• Be like the plinth people: not set in stone