Nuclear power: We are heading for an energy gap, but what can fill it?

Why is nuclear power suddenly in the news again?

The Government is reviewing energy policy and it will soon have to make a decision on whether to build new nuclear power stations. Many of the current ones will be decommissioned within 20 years.

It can take 10 years to build a nuclear power station, meanwhile our energy demands are expected to rise, and Britain's supply of natural gas from the North Sea is declining. Experts believe that if nothing is done soon then British power stations will be unable to supply 20 per cent of the country's peak demand for electricity in 10 years time. In short we are heading for an energy gap and some people see nuclear power as the only way we can fill it.

Why can't Britain just buy more gas or oil from abroad?

Much of this oil and gas comes from unstable regions of the world or is transported through them. Russia could supply much of our needs but there is some reluctance to rely heavily on another country for our strategic supplies.

But another more compelling reason why we can't just carry on burning more fossil fuel is that this generates greenhouse gases and Tony Blair is committed to reducing Britain's CO2 emissions by 20 per cent by 2010 - a target that we are unlikely to hit. In short, Britain has to think of ways of generating electricity that do not involve burning fossil fuels. This leaves nuclear and renewable sources of energy.

How much does nuclear power contribute now to Britain's energy demand?

Nuclear power stations generate up to a quarter of energy requirements. By 2020 nuclear power is expected to fall to less than a third of its current level as ageing power stations are shut down. Britain has 31 operating nuclear reactors at 14 power stations.

Is nuclear power clean?

Generating electricity by nuclear fission does not produce carbon dioxide, the principle greenhouse gas. Nuclear power is estimated to reduce Britain's total greenhouse gas emissions by between 7 and 14 per cent. But mining the uranium fuel for fission reactors requires energy in the form of fossil fuel, so strictly speaking nuclear power generation is not entirely carbon free.

Another problem with nuclear power is what to do with the radioactive waste that it generates. At present Britain is storing this waste temporarily at the sites where it is generated, unless it is sent for reprocessing at Sellafield in Cumbria. Sellafield has a sorry history of polluting the sea and air with radioactive elements. But it has improved in recent years and the latest reactors are far cleaner and more efficient than those designed 40 or 50 years ago.

How much nuclear waste is there and what are we going to do with it?

Britain's radioactive waste would fill several Albert Halls but this includes the low-level stuff that is not particularly dangerous. It is the high-level waste which can remain radioactive for hundreds of thousands of years that is causing the biggest problem.

The Government committee of experts is looking at what to do with this waste and they are due to make their recommendations next year. One option is to leave the waste where it is but in more secure buildings, another is to bury it permanently.

Why do we need nuclear when we can develop clean energy from renewable sources?

This is at the heart of the debate. Wind, wave, solar and other renewable sources are carbon free and do not carry the safety risks attached to nuclear power and its associated radioactive waste.

Not everyone believes these renewable energy sources can fill the energy gap created by a decline in natural gas and nuclear power. The critics say that the technology has a long way to go and even some of the most optimistic assessments suggest that renewables would only fill about half of the expected energy gap. Proponents of renewables argue not enough is being invested in research and development.