On December 3, 2020, the peer-reviewed scientific Journal of Cleaner Production published an article by Spyridoula Gerssimidou and colleagues that compiles a matrix to compare the sustainability impacts of fossil carbon-based with bio-based plastics in the food packaging value chain.
In their study, the researchers applied a Complex Value Optimization for Resource Recovery (CVORR) base-line analysis (first described by Iacovidou et al. 2017), evaluating sustainability impacts according to environmental, economic, social, and technical metrics. Classic life cycle analyses often miss hidden costs and environmental effects that CVORR seeks to cover by applying a multidimensional assessment. The researchers compiled the final results into a matrix that compares the sustainability impacts of conventional and biobased plastics for each combination of chosen metric and life stage. Based on this sustainability matrix, the researchers highlighted and uncovered advantages, disadvantages, as well as knowledge gaps.
One aspect the researchers found often overlooked or insufficiently considered is land-use change. A wide-ranging introduction of first-generation bio-based plastics will inadvertently require converting more land for agricultural use to keep the same degree of food security. Land-use change is associated with negative impacts on biodiversity and increased carbon dioxide emissions that need to be added to the cost of just growing, harvesting, and processing the biological feedstock. According to a study by Escobar et al., the impacts of land-use change caused by bioplastics production, e.g., deforestation, are so significant that they would cancel out the carbon benefits gained from replacing 5% of global fossil carbon-based plastic consumption with renewable carbon-based plastics for 22 years.
From an economic perspective, the production of bio-based plastics is still much more expensive than fossil-based, mainly due to the low oil price and high investment costs of new infrastructure. According to the experts, the biggest challenge will be scaling up and adapting production for future demand. Importantly, addressing the lack of environmental protection technologies in the biorefineries of lower-income countries is also necessary, as these contribute to problems such as air pollution.
For both use and disposal, no clear distinction could be made between conventional and bio-based plastics. Both contain additives and non-intentionally added substances (NIAS) that can migrate during use and storage into foods. However, studies comparing migration from bio-based and conventional plastics are rare, and the overall picture remains unclear. One study by Zimmerman et al. demonstrated that most bioplastics and plant-based materials also contain hazardous chemicals and that both bio-based/biodegradable materials and conventional fossil-based plastics have similar toxicities (FPF reported).
After use, the proper disposal of bio-based plastics is primarily dependent on consumer behavior and effective communication of correct disposal options. The researchers criticize that comprehensive labels are missing, which causes confusion among consumers who wrongly assume all bio-based plastics are compostable and degrade in the open environment. This promotes littering, leads to wrong sorting, and prevents recycling.
Three end-of-life (EoL) management methods were analyzed and compared in this review: mechanical recycling, composting, and energy-from-waste. The latter has almost identical sustainability impacts regardless of the feedstock origin, but it should be considered the last option. Mechanical recycling is regarded as the best EoL option, especially for non-biodegradable bio-based plastics, since it reduces the consumption of raw materials and need for arable land. However, studies finding a net benefit over conventional plastics are lacking. Necessary novel sorting and processing infrastructure still need to be built, and the waste volumes, e.g., PLA, are currently minimal and could contaminate established waste streams such as PET. Only drop-in plastics such as bio PET, bio-PE can use the already existing infrastructure and could therefore be managed without further investment costs. Composting biodegradable plastic waste is seen as a less favorable EoL option as the materials are lost and do not provide valuable nutrients as composted material.
The researchers conclude it is challenging to compare both technologies as fossil-based plastics have a “mature” infrastructure and management system. In contrast, biobased plastics still require “systematic improvements and investments” in the same area. According to the authors, this may favor petroleum-based plastics in the short term, but these factors may become less significant considering the “long-term net sustainability potential.” This also includes the social benefits of creating jobs in low-income countries for production and processing for bio-based.
The low degree of commercialization of bioplastics has also made it difficult to reliably estimate the impacts of increased land use and intensified agricultural activity resulting from the wide replacement of fossil-based plastics with biobased alternatives.
The study uncovered many blind spots currently neglected in introducing bio-based plastics, such as the extension of land-use, lack of comprehensive labeling, and biodegradability standards. At the same time, more research is needed to improve our understanding of impacts on the environment, human health, and society at almost all stages of the plastic life cycle.
The authors conclude that sustainability cannot be easily achieved by replacing fossil-carbon-based plastics with bio-based alternatives. Instead, we should identify essential uses for food packaging and where it is reasonable to replace fossil carbon-based plastics with biobased alternatives. Whenever possible, one should consider reducing the amount of packaging in the system, and new replacements should have the potential to be recycled or reused as well as not harm human health. A similar conclusion has been drawn by Yates et al., which did a systematic scoping review on plastics’ impact on food security as well as its environmental and human health impacts. Holistic sustainability assessments like CVORR are still a relatively novel but necessary tool that will aid in developing a comprehensive regulatory framework spanning the entire plastic lifecycle.
In their analysis, the researchers focused solely on bioplastics produced from first-generation feedstock, which competes with food production. It will also be important to assess in future studies how plastics made from second and third-generation feedstock such as agricultural wastes perform in comparison.
References
Gerassimidou S. (March 1, 2021). “Development of an integrated sustainability matrix to depict challenges and trade-offs of introducing bio-based plastics in the food packaging value chain.” Journal of Cleaner Production
Iacovidou E., et al (September, 2017). “A pathway to circular economy: Developing a conceptual framework for complex value assessment of resources recovered from waste.” Journal of Cleaner Production
Read More
Iacavidou E., et al., (November 2017). “Metrics for optimising the multidimensional value of resources recovered from waste in a circular economy: A critical review.” Journal of Cleaner Production
Neue Verpackung (April 26, 2021). “Wo ist der biologische Abbau eine sinnvolle End-of-Life-Option?”
Escobar, N. (August, 2018). “Land use mediated GHG emissions and spillovers from increased bioplastic consumption.”
