London Mayoral candidate Sadiq Khan wants to use the tube to heat your home
To do that, Khan is considering everything from car-free days and heating systems powered by the tube, to retrofitting London's homes and installing a mass of solar panels.
Speaking last night at the Royal Institute of British Architects, Khan backed a report from the IPPR think tank that called for London to fall in with other major cities the have made the 100% reduction pledge.
"Yes to 100% London. If it's good enough for Sydney and Copenhagen and New York, why not London? I want to be the greenest mayor London's ever had."
The report Khan is backing says it's possible for London to reduce its carbon emissions to zero by 2050 if radical action is taken. The report wants to see: a massive programme to retrofit homes for energy efficiency; the installation of solar panels on public and private roof space; and the phasing out of diesel and petrol delivery vehicles.
Khan said he broadly agrees with the report's call to action, though when pressed by the moderator, Sky News' Afua Hirsch, he couldn't say how any of it would be funded.
He also had some rather far-out ideas of his own. Khan indicated that he wants to replace all buses with a newly commissioned design that would be entirely electric or hydrogen. He is also looking at ways to use waste energy from the tube to heat people's homes, and considering car-free days, which would involve a ban on vehicles in central parts of London.
He also suggests that as broadband speeds improve, people could simply stay at home in order to cut back on their carbon output. "Maybe if we had superfast broadband, they wouldn't have to go to work. They could work from home," he said.
Green issues look set to dominate the London Mayoral elections. Khan's main rival, the Conservative candidate Zac Goldsmith, is a lifelong environmental campaigner whose views on green issues help him win support from people who wouldn't normally vote Tory.
It makes sense for Khan to position himself as a green issues candidate to try and stop Labour voters with strong environmental concerns voting for Goldsmith.