By Alex Kirby
BBC News Online environment correspondent
The UK could secure its energy supply for many decades if it could use its huge reserves of coal, scientists say.
Coal could make a come-back, if we can get rid of carbon
They want the government to give high priority to developing ways to store carbon dioxide underground, to allow it to exploit its abundant coal deposits.
They say the other priority should be to build a new generation of nuclear power plants to meet demand for power.
The scientists, speaking at the Royal Institution in London, said plans for renewable energy use were unrealistic.
Big nuclear improvement
Speaking at a briefing on the future of energy at the RI's Science Media Centre, Professor Ian Fells said he thought it would be "hellishly difficult" to persuade people to invest in nuclear power, but he did not know how the UK would manage without it.
Professor Fells, chairman of the New and Renewable Energy Centre, based at Blyth in Northumberland, told BBC News Online: "The new reactors available now produce just 10% of the nuclear waste the old ones account for.
"There's 10 times as much coal as the oil and gas reserves we have. The Russians told me they're going to build more nuclear plants, because they can't rely on oil and gas - and it's their oil and gas we're planning to rely on!
"If we unlocked our coal it would transform the prospects for using fossil fuel, so carbon sequestration is the key to the future, together with those new nuclear plants.
"I can't believe the UK will ever get far beyond generating 10% or so of its energy renewably - and that would be a heroic effort."
Carbon dioxide (CO2) is the main gas given off by human activities which scientists believe is intensifying natural climate change. Much of it comes from the burning of coal, oil, gas and vegetation.
Sequestration involves trapping CO2 as it is emitted, and storing it in huge reservoirs underground or beneath the sea. It is already being used in Norway, where the carbon helps to force oil out of partly-exploited fields.
Burning coal underground
Professor Fells said the UK was now emitting as much CO2 as in 1997, and he put the chances of reaching the government's target of cutting emissions by 20% by 2010 as "slender, to say the least".
On 10 December 2002, he said, London had been within three minutes of serious power cuts which would have meant quite wide disruption, "and it could happen again".
He thought the UK should aim for an energy mix where coal, gas and nuclear power each provided 30%, and renewables 10%.
Kenneth Fergusson, president of the Combustion Engineering Association, is a former head of the UK's Coal Authority.
He said: "The UK has masses of unmineable coal, and if we could gasify it, it would be important for decades ahead, if not for a century. That means we need sequestration."
Dr David White, an independent energy consultant, said 40 million tonnes of sequestered CO2 was being used annually in the US for oil recovery.
He said there was enough space beneath the North Sea to store Europe's carbon emissions for a century.