© bio-bean limited.

The famous red buses of London could soon use coffee grounds as a fuel source. Sadly – or thankfully depending on your viewpoint – the buses won’t emit a coffee smell.

The test is part of a wider project to reduce pollution from the thousands of buses in the British capital, with increased use of biofuels and hybrid engines.

As an experiment, one bus will, for the next year, be powered by a blend of diesel and coffee oil, which is produced from used grounds. The manufacturers, bio-bean, already use coffee grounds to make burnable logs to use for fireplaces and stoves.

Although in its raw form the coffee oil does have a distinctive aroma, this is heavily reduced by the processing and distillation and then effectively wiped out when combined with diesel.

It’s at least a more pleasant prospect than another British ‘green’ bus: a service that runs between Bristol Airport and neighboring Bath and is powered entirely by biomethane. That gas is produced at a local treatment center that handles both sewage and food waste, meaning many passengers will have made a quite literal contribution to the operation.