Grounds for optimism: Turning coffee into fuel

A hot cup of coffee is the ideal early morning pick-me-up the world over: we drink more than 600 billion cups of coffee every year, according to the International Coffee Organization.

For London based green energy company bio-bean, the lattes, cappuccinos and flat whites we drink are an abundant source of clean energy.

"We've industrialized the process of turning waste coffee grounds into a bio-diesel and a biomass pellet product," Arthur Kay, co-founder and CEO of bio-bean, told CNBC.com in a phone interview.

These bio-fuels – which are clean burning with a high oil content, according to Kay – are then sold to businesses in the U.K. and used to power both buildings and transport. "It's 100 percent carbon neutral," Kay said.

The U.K. produces roughly half a million tonnes of waste coffee grounds each year, Kay added. According to bio-bean, most of this is currently incinerated, sent to landfill or used in anaerobic digestion plants.

Bio-bean collects this waste and takes it to a processing plant near London, where the company converts it into a clean burning fuel.

"We… use a process called 'transesterification' to turn it from a coffee oil into a biodiesel," Kay added. "The residual biomass from that process is in turn used to turn into biomass pellets, so the actual whole process has no waste at all."

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Bio-bean's facility has the capacity to process roughly 25,000 tonnes of waste coffee grounds annually, according to Kay. The final bio-bean product is a second generation, 'advanced', biofuel.

"It's essentially using a product which is already in the carbon cycle and used for a primary purpose. In this case it's coffee, but other examples would be for instance used cooking oil," Kay said. "Essentially, what we've done is we've identified a new second generation fuel that hasn't been valorized before."

The potential for bio-fuels such as the one produced by bio-bean is huge, according to academics.

"Around 8 million tonnes of coffee are produced globally each year and ground waste coffee contains up to 20 per cent oil per unit weight," Chris Chuck, from the University of Bath's Department of Chemical Engineering, told the University of Bath's website earlier this year.

Chuck was co-author of a study in the ACS Journal Energy & Fuels which looked, in part, at how different types of coffee bean affect the fuel properties of biodiesel made from coffee.

"This oil also has similar properties to current feed stocks used to make biofuels. But, while those are cultivated specifically to produce fuel, spent coffee grounds are waste," Chuck added. "Using these, there's a real potential to produce a truly sustainable second-generation biofuel."

While bio-bean currently only operates in the United Kingdom, Kay is keen to stress that the company could eventually expand overseas. "We set up in the U.K. because we happen to be British, but there's nothing unique about the UK's coffee market, in fact it's relatively small," he said.