London mayor Ken Livingstone is set to call on Prime Minister Tony Blair to abandon plans for a new generation of nuclear power stations.
Mr Livingstone will say nuclear energy is expensive and dangerous
In a speech at the annual Greenpeace lecture, he is expected to say that decentralised energy is the solution to many of the UK's energy problems.
Previously, a government advisory panel said that creating more nuclear plants would not help to tackle the issue.
The government is currently undertaking a review of Britain's energy needs.
As North Sea supplies dwindle, nuclear power is seen by some as a more secure source of energy than hydrocarbon supplies from unstable regimes.
Proponents say it could generate large quantities of electricity while helping to stabilise carbon dioxide CO2 emissions.
But Mr Livingstone will set the case against nuclear energy, claiming it is dangerous and expensive, BBC environment correspondent Roger Harrabin said.
He said Mr Livingstone will urge the government to turn to decentralised power generation.
It works by trapping unwanted heat from conventional gas power stations and using it to warm homes, schools and swimming pools.
Conventional gas power stations waste around 40% of energy by creating unwanted heat.
By capturing this heat, decentralised power would save around 20% of greenhouse gas emissions. However, it is a more expensive form of energy.
Mr Livingstone has signed a contract with an energy firm to make London a world leader in decentralised energy, Mr Harrabin said.
Earlier this month, the Sustainable Development Commission (SDC) said doubling nuclear capacity would make only a small impact on reducing carbon emissions by 2035.
The body, which advises the government on the environment, says this must be set against the potential risks.