Life cycle assessment and eco-efficiency analysis of drinking cups used at public events

Abstract

Background, aim, and scope

At the request of the Public Waste Agency for the Flemish Region, the Flemish Institute for Technological Research performed a life cycle assessment (LCA), according to the International Organization for Standardization (ISO) 14040 procedures (ISO 1997, 1998, 2000, and ISO 2006), followed by an eco-efficiency analysis of four alternative types of drinking cups for use at public events. The results of the LCA study served as input for the eco-efficiency analysis in which the costs related to the four cup systems were studied and combined with the environmental impacts. The objective of this study was to gain insight into the current environmental impacts and costs related to existing systems for drinking cups at public events in Flanders (Belgium) in order to outline a well-founded policy with regard to this subject. Since the results of this comparative study are publicly available, a critical review was performed according to ISO 14040 (review by interested parties, using a review panel) after each stage (goal and scope, data inventory, impact analysis/interpretation, eco-efficiency analysis) during the study.

Methodology

Four types of cups were analysed; the reusable polycarbonate cup (PC), the one-way polypropylene cup (PP), the one-way PE-coated cardboard cup and the one-way polylactide cup (PLA). The functional unit is defined as ‘the recipients needed to serve 100 l of beer or soft drinks at a small-scale indoor respectively a large-scale outdoor event’. This definition included the production of the cups, the consumption stage (at the event) and the processing of the waste. The data inventory focused on specific data supplied by different stakeholders in Flanders (and Belgium). Based on data collected for specific events, an average typical small indoor and large outdoor event was defined, respectively. One important aspect in this context was the trip rate for the reusable cups, meaning the average number of times one cup can be used before disposal. Based on practical experiences combined with literature research, a trip rate was defined for small- and large-scale events, respectively. Since this factor was very important but also very open for debate, a sensitivity analysis was performed on the trip rate. The impact analysis was based on the Eco-Indicator 99 methodology (Hierarchist version H/A; Goedkoop and Spriensma 2000). The main reason for using this methodology was that it allows the calculation of one weighted environmental indicator for each alternative, which was needed as input for the eco-efficiency analysis. The cost indicator, which was based on similar system boundaries and assumptions as the environmental indicator, was calculated from a societal perspective. Both indicators were combined in an eco-efficiency portfolio, with the average in the centre point and the number of standard deviations indicated on the axes.

Results and discussion

For the environmental profile of the individual cup systems, the total life cycle of the cups was divided in different life cycle stages. Based on the individual profiles it could be concluded that the most important environmental contribution when using reusable PC cups at small indoor events is caused by the production of the cups and the transport of the cups from the distributor to the event and back. On large outdoor events, the (machine) cleaning of the cups also contributes significantly to the total environmental impact. For one-way cups (PP, PE-coated cardboard and PLA) used at small indoor as well as large outdoor events, the production of the cups dominates the environmental profiles. By comparing the environmental impacts of the four types of cups on both types of event, it became clear that none of the cup systems has the highest or the lowest environmental score for all environmental impact categories considered in the study. Based on these comparisons, it was not possible to make a straightforward conclusion for the selection of the most favourable cup system with regard to the environment. When comparing the individual cup systems between small indoor and large outdoor events, the reusable PC cup differs the most between both types of events. The environmental burden increases significantly for PC cups moving to larger scale events. This can be explained by the lower trip rate and the machine cleaning instead of manual cleaning of the cups after large events. For the other types of cup systems, the difference going from a small to a large scale event is negligible. The combination of the environmental and cost indicator in the eco-efficiency analysis led to a different result for small indoor compared to large outdoor events. The eco-efficiency portfolio for small events showed that the reusable PC cup has a significant more favourable environmental score than the one-way cups, but the cost indicator is significantly higher. This may be an argument to initiate a promotion policy for reusable PC cups at small events. For large events, the eco-efficiency portfolio did not result in a significant winner with regard to the environmental or cost indicator. To determine the influence of a change in the inventory data on the results of the impact assessment and eco-efficiency analysis, some sensitivity analyses were performed, for example for a variation in trip rate, a variation in the cleaning of the cups during and after the event (manual versus machine), and a future scenario for the PLA cups (change in production process, end-of-life treatment, etc.).

Conclusions

The comparative LCA study according to ISO did not provide an overall environmentally superior cup system. In the eco-efficiency analysis, using a subjective weighting step, the reusable PC cup system resulted to be significantly better compared to the other cup systems for small events from an environmental point of view. Two aspects that improved the overall quality of this study are on the one hand the consultation and collaboration of the stakeholders during the process to supply information, check the inventory data and give feedback on the preliminary results and on the other hand the work of the review panel in order to ensure that the provisions from the ISO 14040 series regarding methods, data, interpretations and reporting are taken care of. It was appreciated by the commissioner and all stakeholders that the results of the study are communicated in a transparent way, with a discussion of the necessary differentiations.

Recommendations and perspectives

From the comparative LCA-study according to ISO, none of the four considered cup systems has overall superior or inferior performance neither at small nor large events. This means that there are no scientific arguments for a policy of encouraging or discouraging one of the four cup systems based on the LCA-results. The eco-efficiency assessment (with its subjective choices and limitations, that the commissioner of the study should realise and support in the context of this study) has shown that in the base case for small events the PC cup system shows a significant more favourable environmental score than the other three cup systems on the market. As the costs of the reusable PC cup system are higher, a policy of promoting the system can be considered based on the more favourable environmental score. Policy makers should agree on the subjective value choices made while weighting different impact or damage categories.