Comparative life cycle assessment of drinking straws in Brazil
Catégorie : Modélisation
Date :27 novembre 2020
Avis TSC : Voici l’exemple typique d’une analyse de cycle de vie (LCA) qui conduit à la conclusion erronée suivante : il est préférable d’utiliser des pailles à usage unique plutôt que des pailles réutilisables. Sans rentrer dans les détails, les hypothèses d’impacts et le périmètre de l’étude font que les résultats présentent cette tendance étrange. Heureusement, les auteurs sont très critiques sur leurs conclusions et ouvrent la discussion sur les limites des LCA et la nécessité de normaliser les hypothèses, en particulier pour la quantification des impacts sur l’environnement. Donc un « must read » dont je ne vous suggère pas la lecture, sauf de l‘avis.
There have been numerous discussions about plastic drinking straws and their impacts on the natural environment, reflecting on public policies and companies’ operation, while alternatives to substituting plastic-based products have been proposed. However, making decisions without measuring trade-off conditions between the different scenarios may lead to higher impacts elsewhere on the life cycle or even in other areas of protection. To deepen this discussion, this paper aimed to quantify the potential environmental impacts of different drinking straws as well as find possible break-even situations. A comparative life cycle assessment (LCA) was performed to assess six different drinking straws (plastic, stainless steel, glass, paper, bamboo and jute) from cradle-to-grave. A hybrid life cycle impact assessment (LCIA) method was applied following the characterization models recommended by ILCD. Sensitivity analyses included reuse rate, washing condition, the ancillary kits usage, End-of-Life (EoL) strategies and the inclusion of an indicator to account for the marine litter impacts from Life Cycle Inventory (LCI). Results showed that for baseline scenarios, plastic drinking straws have a better environmental performance if compared to reusable straws and has a favourable performance in 10 of 11 categories if compared to paper drinking straws. Water and detergent consumptions during the use phase and the manufacturing of additional elements (bag, brush) are the main drivers for this potentially higher environmental impact. Sensitivity analyses, however, showed that certain consumption patterns may lead to a break-even situation, especially when plastic drinking straws are disposed incorrectly into the natural ecosystem. Accounting for the impacts of marine litter may lead to a change in the decision-making depending on the significance (weight) attributed to the marine litter indicator. These outcomes reinforce the importance of understanding trade-offs during the entire life cycle of products and demonstrate that policies directed to product substitution should be carefully grounded. Recommendations on reusable straws rely on simplifying their “kits”, expanding reuse rates and improving the washing process. For single use straws, waste collection and correct disposal are mandatory. The lack of a LCIA methodology to account for the environmental impact of mismanaged plastic waste on ecosystems, especially in the marine compartment represents an important issue to be further developed, from which, more realistic scenarios could be outlined for any product.