What is the most sustainable end-of-life option for paper cups used for hot beverages? Wageningen Food & Biobased Research and TNO conducted a life cycle assessment study for the Dutch Government to compare two end-of-life routes after separate collection: converting the used cups into toilet paper and tissues in a paper factory (recycling), and digestion of the cups to create biogas – and subsequently produce compost of the digestate. Recycled cups were shown to have a better environmental performance, while digestion and composting results in a higher net reduction in CO2 emissions.
‘What is the most sustainable disposable cup for hot drinks?’ is a question that has been keeping minds busy for decades. Over recent years, various companies and governments have opted for the large-scale purchasing of specific, sustainable types of hot beverage cups. The Dutch government, for instance, decided to purchase paper cups with a polylactic acid (PLA) coating. PLA is a biodegradable and biobased plastic.
At the government’s purchasers request, Wageningen Food & Biobased Research and TNO subjected these types of cups to a life cycle assessment study. Until 2017, the cups were being processed in a waste energy plant, but there are now two new end-of-life routes available: recycling and digestion plus composting. No other waste management route than these three are expected to become available in the coming years.
Climate change and other environmental effects
To perform a proper environmental analysis, the scientists used the ReCiPe midpoints method combined with environmental costs. At the request of the client, the results were also presented as a so-called carbon footprint, which only addressed the ‘climate change’ effect category.
“When evaluating the full environmental profile, the environmental analysis shows that the recycling route performs best by avoiding €1.22 in environmental costs per 1000 cups,” says Martien van den Oever, project leader at Wageningen Food & Biobased Research. “One of the reasons for this result is that up to 89% of the collected coffee cups are suitable for recycling, and therefore preventing the use of primary pulp. This avoided use of primary pulp in particular means saving on environmental costs for cultivation of trees and fine particulate matter formation. Although the digestion route takes a second place with €0.45 in avoided environmental costs, it is still a better performance than the €0.28 figure of discarded cups processed in the waste energy plant.”
When only looking at the climate change effect (CO2 emissions), the scientists drew an entirely different conclusion. Van den Oever: “Here the digestion route performs better by saving some 5.4 kg CO2 eq. per 1000 collected cups. This is followed by the waste energy plant, with recycling in third place. It is surprising to see that recycling performs the poorest in this regard. The reason for this is that when you only consider climate change, the avoided CO2 from recycling is limited as a result of the limited CO2 emissions in the production of primary pulp, while digestion and incineration perform well because they avoid the combustion of natural gas and, therefore, CO2 emissions.”
Government chooses recycling
Based on these results, the Dutch Ministry of Economic Affairs and Climate Policy has now chosen to recycle the discarded hot beverage cups made from paper with a PLA coating. Van den Oever: “It is eventually up to the client which choice best suits their policy goals. It is our responsibility to choose a proper method for the analysis, and indicate the implications of the various options based on the available data.”
The research was financed by the Dutch Ministry of Economic Affairs and Climate Policy.