It is estimated that Scotland produces around 40,000 tons of coffee waste per year and this is mostly sent to landfill. Every ton of spent coffee produces 1.7 tons of CO2. It also has a higher calorific value than wood due to its high oil content. This makes coffee grounds a potentially valuable bioenergy feedstock.

Challenge

Artisan Roast Ltd and Energy Recovery Systems (ERS), in collaboration with the University of St Andrews, wanted to investigate the utilisation of coffee grounds as a feedstock waste to produce energy by burners and direct waste fuel cells, a novel technology that can convert the waste into energy and heat in a single step.

Solution

Supported by just under £20k funding from IBioIC’s Feasibility Fund, Artisan Roast and EERS worked with Damiano Bonaccorso and John Irvine from the University of St Andrews.

Artisan Roast worked on the coffee grounds supply chain and the business case, while EERS worked on a process to pre-treat the coffee grounds for biomass boiler use. The team at St Andrews used specialist equipment that the industrial partners would not otherwise have been able to access to perform analysis on the use of coffee grounds for fuel in a biomass boiler.

EERS and Artisan Roast developed a process to turn coffee grounds into around 12% of oil, 56% of water and 32% solids by-product that can be used as fertilizer as well as highly energetic bio heat pellets. Artisan Roast conducted detailed business analysis to determine how operations might work and whether they are economically feasible. 

Outcome

The research done at St Andrews confirmed spent coffee solids with the oils fraction included as a valid alternative for wood as biomass fuel.

Artisan Roast’s business analysis showed the operation can be profitable and therefore, interesting as a business, as long as the roasters are involved directly in the operation and ready to take some responsibility for the waste generated by their product, as is normal for any circular economy solution.

While there are challenges around certification of new products and legislation that need to be overcome, it is expected that legislation will move in the direction of making goods producers responsible for the waste generated by their product.

The partners are continuing to work together on a product using spent coffee grounds for coffee logs instead of using in biomass boilers, for which it is difficult to get certification.

The project partners were also introduced to the Energy Technology Partnership to help with legislative challenges.