The perks of a cup of coffee don't have to end when the grounds are dumped in the trash. Used coffee grounds have been used to make warmer clothing, pave roads, capture carbon from the air, and even suck up sewer stench, and now a London-based company has partnered with Shell to turn the leftovers from this human go-juice into biofuel to help run the English capital's expansive bus network.

Bio-bean has been recycling coffee for a few years now, heating homes and buildings with what it calls Coffee Logs – burnable briquettes made of old grounds rather than wood. Coffee-based biofuels have always been a goal too, and now, with the backing of Shell and the fuel blending company Argent Energy, Bio-bean is producing a biodiesel as well as the infrastructure to obtain the otherwise-wasted grounds from around London.

The companies call the fuel a "B20" blend, and it's made by first extracting oils from discarded coffee grounds. These are mixed with other fats and oils and then blended again with mineral diesel to create a fuel with a 20 percent biocomponent. When this biodiesel is fed into London's buses, it should reduce their carbon dioxide emissions by 10 to 15 percent. On top of that, Bio-bean says its facility can process some 50,000 tonnes of coffee grounds every year, which is about a quarter of London's annual coffee grounds waste.

It sounds good on paper, but as with any of these biofuel systems, you have to wonder about the net gain for the environment. Do the effects of shipping all those coffee grounds from cafes and restaurants around the city, as well as processing them in the factory, create more waste and pollution than is saved by recycling the grounds in the first place?

Of course, it's impossible to know at this point, but that doesn't mean we shouldn't bother at all. This process is still a step in the right direction, and those benefits could be amplified when paired with other environmentally friendly initiatives – if, for example, the trucks transporting the grounds were electric, and the factory was taking measures to cut down its own emissions.

This first stage of the project is set to produce 6,000 L (1,585 gallons) of coffee oil for use in selected London buses. In later stages the companies plan to produce a "pure-blend" that does away with the other fats and oils currently added to the mix.

Sources: Shell, Bio-bean

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