Britain faces winters of blackouts and energy price hikes because of a looming crisis in generating capacity, a power and engineering industry union warns.
Amicus says Britain risks becoming dependent on foreign gas imports from unstable countries.
It says the government must invest more in coal, renewable and nuclear energy if it is to maintain power supplies.
But the government said the outlook for power supplies this winter was good and accused the union of “scaremongering”.
BBC industry correspondent Patrick Bartlett said Britain had become increasingly reliant on gas for its power.
“But with the country’s gas reserves now running down, Amicus says we risk becoming dependent on imports from unstable countries,” he said.
“As recent supply problems have shown, a gas shortage could lead to big rises in energy bills.”
CBI chief Digby Jones told the BBC’s Today programme rising power costs, such as a 75% rise in oil costs over 18 months, were already having a “huge impact on manufacturing”.
Amicus says power supply problems are compounded by new EU regulations controlling carbon emissions, which it believes could mean an end to coal-generated power in Britain by 2008.
Colder winters brought on by global warming and the closure of older magnox nuclear plants will make things worse, it says.
Amicus and the National Union of Mineworkers plan to meet with Chancellor Gordon Brown to discuss concerns.
They want urgent investment in “clean-burn coal technology”.
And it wants more pressure on power companies to ensure coal-fired stations meet new EU requirements and more investment in designing and constructing new power stations.
General secretary Derek Simpson said: “We could be suffering routine blackouts in the next few years and the sort of energy price hikes we have seen in recent weeks because of the increasing reliance on foreign supplies from unstable countries.”
But a spokesman for energy regulator Ofgem said it was predicted there would be more power available this year than 12 months ago.
And Greenpeace UK director Stephen Tindale said the solution was to be found in more investment in energy efficiency and renewable energy.
He said: “Supporters of nuclear power, like Amicus, regularly claim the lights could go out at any moment.
“But their real fear is that government support for nuclear power might be switched off.”