Bio-bean has teamed up with Royal Dutch Shell to create a new bio-fuel, which can be used without having to modify the vehicles, to help reduce emissions.
Bio-bean founder Arthur Kay said: "It's a great example of what can be done when we start to reimagine waste as an untapped resource. Our Coffee Logs have already become the fuel of choice for households looking for a high-performance, sustainable way to heat their homes."
The firm says it would take around 2.55 million cups of coffee to develop enough biofuel to run one London bus for a year, which doesn't seem so bad, given that Londoners create 200,000 tonnes of coffee waste every single year.
Back in 2015, Transport for London confirmed their plans to have almost a third of London's bus fleet running on a greener blend of diesel.
Matthew Pencharz, Deputy Mayor for Environment and Energy, said at the time: "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. This is ongoing progress for running our bus fleets on waste products and cutting CO2. We will continue to work with our industry partners to use more of London's used cooking oil turned into biodiesel right here in the city, creating green jobs and fuel self-sufficiency benefits."