Nearly one third of London’s red buses will run on waste fat and oil by March next year.
Bus operators Stagecoach and Metroline have signed deals with Argent Energy to supply them with B20 green diesel.
The cleaner burning fuel is made from blending diesel with renewable biodiesel from waste products, including cooking oil and tallow from the meat processing trade.
Transport for London (TfL) says the change in fuel will result in significant reductions in CO2 emissions of 21,000 tonnes each year. This follows a 48,000 tonne CO2 reduction from 2013 levels following the introduction of lower emitting hybrid buses.
By March next year, almost 3,000 of the capital's 8,900 buses will be powered by the waste fat fuel blend. Over 600 buses operating out of four Stagecoach depots have already been using B20 for two months on a trial basis.
London’s deputy Mayor for Environment, Matthew Pencharz, said: “As a leading global city, London has an important role to play in reducing greenhouse gases and minimising our contribution to climate change.
“Just a fortnight after the Mayor's visit to the Paris conference on preventing global warming, I am very pleased to announce that nearly a third of London's buses will now be running on biodiesel, slashing the overall carbon emissions of the fleet and making use of fuels that would otherwise be clogging up our drains.
“These buses will be a proud addition to what is already the greenest bus fleet in the world, including hybrid, pure electric and pure hydrogen vehicles.”
TfL has said it will require all biodiesel to be sourced from waste, rather than crop-based feedstocks. It is estimated that buses running on waste-based B20 produce 10 per cent less 'well to wheel' carbon emissions than a bus using ordinary diesel.
London’s fleet of buses already has over 1,500 hybrid electric buses and 15 buses that run solely on electricity.
Last month, it was announced that Bristol was introducing buses powered by human waste.