Coffee is the second most important commodity after crude oil and its commercial importance is steadily growing. The large amount of residual material produced during the manufacture of the beverage is moist spent coffee grounds, which can hardly be collected from private households due to rapid mold growth. However, high-quality recycling approaches exist for spent coffee grounds from the catering and commercial sectors, but these have so far faced significant market barriers.
The aim of the project is to develop a industrially scalable approach for converting commercially available spent coffee grounds into high-quality intermediates. A special focus is set on the fact that these intermediates not only represent a raw material for biobased products, but also lead to previously unattainable improvements in the properties of the end products or replace other, less available raw materials.
Development steps and scale-up
As a first step in the overall process chain coffee oil is extracted from spent coffee grounds with a solvent. The recovered coffee oil is transesterified with an alcohol to fatty acid alkyl esters and subsequently fractionated. The fraction with a high C18:2 alkyl ester is catalytically converted to a plastic additive. The de-oiled spent coffee grounds are used as innovative additive for papers and paperboards. An overreaching material flow analysis of all process steps delivers a cost indication for intermediate and final products.
As always, the scale-up of a process from the laboratory to industrial production poses one of the challenges to be tackled. The envisioned process chain as a whole is highly innovative and provides an important contribution to the use of bio-based raw materials in the bioeconomy.
Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT