A new study by Netherlands-based Wageningen University & Research has concluded that compostable bioplastic coffee capsules are more sustainable than both aluminium and virgin plastic capsules.
The study assessed greenhouse gas emissions and employed the Material Circularity Indicator (MCI) developed by the Ellen MacArthur Foundation to quantify the circularity of the different materials. It considered recycling rates, recycled content, process yield, biobased content, reusability, and lifespan. Additionally, it examined various end-of-life scenarios, such as industrial composting (specifically for compostable capsules), recycling through lightweight packaging waste collection, incineration with energy recovery, landfill with energy recovery, and mono-collection for aluminium capsules.
“The unique aspect of this research is that we haven’t just looked at greenhouse gas emissions, because that is only part of the story,” said project lead Ingeborg Smeding. “By considering also the circularity of the materials we gain a broader perspective of the sustainability of the various options.”
Results show that compostable plastic capsules are the most sustainable option, with an MCI of 100% (fully circular) when the capsules are composted. However, in most European countries, except for Italy for example, compostable coffee capsules aren’t yet accepted in the organic waste bin by waste collection operators in Europe, which has led European Bioplastics to make a renewed call for European legislators to change their approach.
“This needs to change, and the only way for this to happen is by embracing the composters and their legitimate concern of non-compostable coffee capsules contaminating their waste streams,” said Hasso von Pogrell, managing director of EUBP. “Legislation that phases out the use of non-compostable plastic coffee capsules is inevitable. Therefore, prior to the plenary vote in the European Parliament on the Packaging and Packaging Waste Regulation (PPWR) on Nov. 22 and the discussions on Member States level towards a general approach in the European Council, we call on the European legislators to take this reasoning into account. Without complete support from local and national governments, it won’t be possible to allow the deployment of this circular solution, which can not only contribute to the production of high-quality compost but also reduce the use of other materials considered less sustainable for this type of application”, he concludes.
The ’less sustainable materials’ are virgin plastic and aluminium, which the Wageningen University & Research study showed to have an MCI of less than 50% and 60%, respectively. Virgin plastic coffee capsules are the worst option, as neither the packing nor its content are recycled. Moreover, their market offering impairs the case for allowing compostable bioplastic capsules in the biowaste bin, von Pogrell argues.
“While composters may be able to sort out capsules made of aluminium, should they accidentally end up in the biowaste bin, they will not be able to distinguish between compostable and non-compostable plastic coffee capsules. However, if we want the operators of organic recycling factories to embrace the idea of allowing compostable coffee capsules to enter the biowaste stream, thereby profiting from the nutrients contained in the capsules in form of coffee residues, they will need to be confident that all plastic capsules entering their waste stream are indeed certified compostable and need not be sorted out prior to processing the biowaste”, he argued.
The study showed that aluminium capsules are a second-best choice if they are collected separately through systems designed exclusively for returning these capsules (mono-collection): the aluminium is then recycled, and the coffee composted. However, the MCI is lower compared to compostable capsules, even when recycled aluminium is used to produce the capsules. A closed recycling loop is not feasible because untargeted trace elements will accumulate in the aluminium, making it less pliable over time. Another main challenge is to achieve a high participation rate in a voluntary mono-collection system.