Compostable Coffee Capsules Are The Most Sustainable Choice

Wageningen University & Research has assessed the environmental impacts and circularity of different materials for single-use coffee capsules, taking into account different end-of-life scenarios. The conclusion is that when both material circularity and greenhouse gas emissions are taken into account, compostable capsules are the most sustainable choice.

“Billions of coffee capsules are used in Europe every year. Although coffee grounds contribute the most to greenhouse gas emissions, the material of capsules still has a significant impact,” explains project leader Ingeborg Smeding. She and her colleagues analyzed the impact of three types of capsules: compostable biobased capsules, conventional plastic capsules and aluminum capsules.

Material Circularity Indicator
Smeding: “What is unique about this research is that we did not only look at greenhouse gas emissions, because that is only part of the story. By also taking the circularity of the materials into account, we gain a broader perspective on the sustainability of the different options.” Circularity is quantified with the Material Circularity Indicator (MCI), developed by the Ellen MacArthur Foundation. This indicator is one of the most complete instruments available, because it includes the amount of material recycled, the use of recycled content, efficiency of the recycling process, biobased material use, reusability and average lifespan.

Compostable capsules most durable, aluminum second best
The main conclusion of the research is that compostable plastic capsules are the most sustainable, when both greenhouse gas emissions and circularity are taken into account. Their MCI is 100% (completely circular) when composted: the materials are both biobased (not fossil) and biodegradable. Both coffee grounds and capsule material can remain in the cycle because they are “organically recycled” into compost via the biosphere. Compostable options remain sustainable even when consumers throw away the capsules in the 'wrong' container. The main stumbling block in the Netherlands: compostable coffee capsules are currently not accepted as separately collected organic waste.

Aluminum capsules are the second most sustainable material when collected separately through systems designed exclusively for the return of these capsules (mono-collection): the aluminum is then recycled and the coffee composted. However, the MCI is lower (about 60%) compared to compostable capsules, even when recycled aluminum is used to produce the capsules. A closed metal cycle is not feasible because foreign elements accumulate in the aluminum, making it less flexible over time. Another major challenge is achieving a high participation rate in a voluntary mono collection system.

Finally, the research shows that conventional fossil fuel-based plastics do not fit into a circular economy, as neither the plastic capsules nor the used coffee grounds are recycled. The MCI is below 50%.

End-of-life scenarios
The study included the following end-of-life scenarios: industrial composting (only for compostable capsules), recycling via packaging waste collection (PMD), incineration with energy recovery, landfill with energy recovery and mono-collection (only for aluminum capsules).

Funding the research
This research is part of the project 'Increasing circularity through the use of biobased and/or industrially compostable materials'. It was carried out by Wageningen Food & Biobased Research, subsidized by TKI BBE and financed by Advanced Technology Innovations, De Koffiejongens, NatureWorks, Novamont, TotalEnergies Corbion and the Ministry of Infrastructure and Water Management.