Roof wind turbines 'to slash bills'

London homeowners will have the chance to buy roofmounted wind turbines that could cut hundreds of pounds from electricity bills.

The 5ft-wide turbines will go on sale later this year from British Gas, priced at about £1,500.

The initiative came as new research showed that almost 250,000 householders in London are interested in installing renewable energy systems.

The miniature turbines are well suited to Britain's breezy climate and will provide enough power to supply "always on" appliances such as fridges and freezers, and TVs and computers that are on standby. On more windy days the electricity generated will also be enough to keep some lights going.

If they prove popular they could turn London streets into tiny urban versions of the huge wind farms that have sprung up in Britain's countryside over the past decade.

Dr Diana Montgomery, head of environment strategy at British Gas, said: "Having a roof-top turbine means householders can save money and help do their bit for the environment. Initial estimates show one unit could cut annual electricity bills by up to one third and reduce CO2 emissions by half a ton per annum."