Replacing plastics worsens greenhouse gas emissions: study

Replacing plastics with alternative materials is expected to lead to higher greenhouse gas emissions, according to research from the University of Sheffield.

The study, published in the journal Environmental Science & Technology, examined plastics and their substitutes in diverse sectors such as packaging, construction, automotive, textiles, and consumer durables. These industries account for a substantial share of worldwide plastic consumption.

Alternatives to plastics raise greenhouse gases

The study findings, published in the journal Environmental Science & Technology, reveal that among the 16 applications analyzed, plastic products yield lower greenhouse gas (GHG) emissions in 15 cases compared to their alternatives. The reduction in emissions ranges from 10% to as high as 90% throughout the product life cycle.

To gauge environmental impacts, researchers from Sheffield employed a life cycle assessment (LCA) tool, enabling a comparative analysis of different products' environmental effects. By adopting an LCA approach, the study evaluated GHG emissions associated with plastic products versus alternatives across various sectors.

Even when focusing solely on direct life-cycle emissions, plastics maintain their superiority in nine out of 14 applications. Factors such as lower energy intensity during production and the lightweight nature of plastics contribute to their reduced environmental footprint compared to alternatives like glass or metal.

Furthermore, plastics exhibit superiority in upstream processes, encompassing production and transport, in 10 out of 16 applications. This advantage arises from their lower energy intensity and lighter weight, emphasizing the efficiency of plastic materials in emission mitigation, as indicated by the study.

Informed decisions vital for environmental policy

Dr. Fanran Meng author of the study and, Assistant Professor in Sustainable Chemical Engineering at the University of Sheffield, emphasized the importance of informed decision-making in environmental policymaking. 

He stated, "Not all alternative or recycled products are better for the environment than the products they replace. Environmental policymaking needs life cycle assessment guided decision-making to make sure that GHG emissions are not unintentionally increased through a shift to more emission-intensive alternative materials. Demand reduction, efficiency optimization, lifetime extension, and reuse/recycling are win–win strategies to reduce emissions effectively. Solely focusing on switching to alternative materials is not."

The study also underscored the intricate nature of indirect impacts from background systems surrounding plastics, which significantly influence certain applications. For instance, in scenarios such as insulation and hybrid vehicle fuel tanks, these indirect impacts overshadow the direct emissions of plastics, providing a nuanced perspective on their environmental performance.

Plastic packaging crucial for reducing food waste

Additionally, plastic packaging serves a vital role in preserving food quality across various categories, mitigating food spoilage and the GHG emissions it generates. This essential function highlights the unmeasured environmental benefits of plastic packaging compared to alternative materials.

The research findings suggest that optimizing plastic usage, extending product lifetimes, increasing recycling rates, and improving waste collection systems may offer more effective strategies for reducing emissions associated with plastic products.

Dr. Meng underscored the necessity of employing life cycle assessment for understanding environmental impacts of plastics and alternatives. He emphasized, "We need to consider all of these impacts when choosing which materials to use in products to ensure we are using the right materials for the right purpose and to help us develop a sustainable plastics sector."

Furthermore, the research team suggested expanding future modeling to incorporate reusable bioplastics, compostable, and biodegradable alternatives. These were omitted from the study due to small market values and insufficient data on reuse.