Although today's White Paper on energy is accompanied by a "consultation" about nuclear power, pronouncements from both of Britain's prime ministers leave little room for doubt that the British Government believes that the country's energy problems cannot be solved without recourse to a new generation of nuclear power.

Ministers insist that although nuclear power is not a silver bullet, it has to be part of the picture - that without it we can neither reach our goals of reducing carbon emissions nor avoid placing ourselves in the hands of Mr Putin and his successors in title to Russia's vast reserves of gas. I believe that the Government is profoundly wrong about nuclear power and has allowed itself to be rushed into a bad decision by a clever but deceptive public relations campaign by the nuclear industry.

The first thing to grasp about energy is that electricity makes up only about a third of the picture. Most of the energy used in Britain goes into heating buildings and powering vehicles - for neither of which is nuclear power a plausible source. Nuclear power stations supply less than five per cent of our primary energy. Perhaps more surprisingly, a similar point can be made about gas, the vast majority of which goes to heat buildings rather than to produce electricity. If we want to reduce our dependence on gas, we would be much better employed in improving the insulation of our houses than building nuclear power stations.

The second point to grasp about energy policy is that timing is all. The Government points out that a large amount of existing nuclear capacity is due to close in the next 15 years. It gives the impression that unless we agree to replace it with new nuclear power stations we are in danger of suffering power shortages. But this is nonsense. The Government in its more honest moments admits that even with radical reform of the planning and licensing system, nuclear power stations take so long to bring on line that they can contribute little before 2020. That means that whatever happens on nuclear power, we will have to find other ways of filling the gap. We need to be looking now for the most efficient and environmentally friendly way of filling that gap and not let ourselves be distracted by nuclear.

And what about the period after 2020? No one can be certain about a period so far in the future, but it is clear that by that time a number of safer and more attractive technologies will be available - from carbon capture and storage (which the European Commission proposes to make compulsory from 2020) to tidal power, wave power and offshore wind power.

Carbon capture will allow the continued use of gas and coal, at least for a transitional period until we can move to a fully renewable system - which has to be the ultimate aim of energy policy both from the point of view of climate change and of security of supply. Carbon capture has great advantages over nuclear power - it is far more flexible than nuclear power, which means that it is much better at operating in conjunction with renewables and with microgeneration; it poses no challenges for proliferation policy - one of the big difficulties of a world-wide nuclear renaissance - and far fewer problems for counter-terrorism policy and thus for civil liberties; and it does not need the hidden subsidies that nuclear continues to receive, for example the cap on liability for nuclear accidents.

If we attempt to promote both nuclear power and carbon capture we risk undermining early investment in carbon capture, and, in the long term, we risk crowding out renewables. New analysis for the Liberal Democrat parliamentary party shows exactly that: by 2050 the effect of allowing nuclear power to operate alongside carbon capture and renewables is to reduce the contribution of wind power and wave power. It will hardly affect the share of gas and coal carbon capture - largely because nuclear cannot compete economically in the role of flexibly balancing the electricity grid.

That would not leave us significantly better off in terms of avoiding imported gas, but it would leave farther away a fully sustainable system.

Instead we should be aiming at a non-nuclear low carbon electricity generating system. With sensible incentives, especially a carbon price for the electricity generating industry around the levels suggested by Sir Nicholas Stern, it is entirely possible by 2050 to eliminate more than 90 per cent of the carbon emitted in 1990. No one doubts that the physical resources exist in Britain. In terms of the potential of wind, tide and wave we have power for many times existing demand. The only question is how to get there.

The writer is the Liberal Democrats' spokesman on energy