Plastic alternatives result in increased GHG emissions, finds British LCA study

17 Apr 2024 --- Researchers at the University of Sheffield, UK, have found that plastic products result in lower GHG emissions compared to alternative materials.

The researchers examined the environmental impact of plastic products versus non-plastic alternatives for 16 applications across five sectors, including packaging, building and construction, automotive, textiles and consumer durables. 

In the applications assessed, plastic products were found to release 10–90% fewer emissions across the product life cycle. Furthermore, the researchers found no suitable plastic alternatives in some applications, such as food packaging. 

The study by Dr. Fanran Meng from Sheffield’s Department of Chemical and Biological Engineering, in collaboration with researchers from the University of Cambridge and the KTH Royal Institute of Technology, used LCA to evaluate GHG emissions.

“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 ensure that GHG emissions are not unintentionally increased by shifting to more emission-intensive alternative materials,” says Dr. Meng.

“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 finds few alternatives to plastics in food packaging, primarily due to higher levels of spoilage.Advantageous material
The study found that even when focusing solely on direct life-cycle emissions, plastics maintain their advantage in nine out of 14 applications. 

Factors such as lower energy intensity during production and the weight efficiency of plastics contribute to their reduced environmental footprint compared to alternatives like glass or metal.

Plastics demonstrate superiority in upstream processes, including production and transport, in ten out of 16 applications. This advantage stems from their lower energy intensity and lighter weight, highlighting the efficiency of plastic materials in mitigating emissions, according to the study.

“These results demonstrate that care must be taken when formulating policies or interventions to reduce plastic use so that we do not inadvertently drive a shift to non-plastic alternatives with higher GHG emissions,” note the researchers.

“For most plastic products, increasing the efficiency of plastic use, extending its lifetime, boosting recycling rates, and improving waste collection would be more effective in reducing emissions.” 

Food packaging suitability
The authors say plastic packaging plays a crucial role in preserving food quality across a wide range of categories, helping to prevent food spoilage and the GHG emissions it causes. This essential function highlights the unmeasured environmental benefits of plastic packaging when compared to alternative materials.

“There are few alternatives to plastics in food packaging across a broad range of applications. This is primarily due to higher levels of food spoilage when using non-plastic alternatives. An evaluation of 20 common food categories reveals that plastic packaging is used in more than 90% of products sold in six categories (breakfast cereal, yogurt, cheese, still bottled water, and fresh and frozen meat),” reads the study.

“In another eight categories (milk, edible oil, chocolate, nut/seed mix, sweet biscuit, packaged bread, juice and rice), plastics are present in the packaging of more than 50% of products sold. The remaining six categories (ice cream, carbonated soft drink, pasta, jam and preserve, soup and pickled products) use plastics in less than 50% of the products sold, as plastics have viable alternatives in use.” 

“The role of plastic packaging in keeping food from spoiling translates into a significant but often unquantified GHG benefit relative to alternatives,” the study underscores. Researchers say factors such as lower energy intensity during production and the weight efficiency of plastics contribute to their reduced environmental footprint.

Life cycle assessments
The study, “Replacing Plastics with Alternatives Is Worse for Greenhouse Gas Emissions in Most Cases,” was published in the Environmental Science & Technology journal. 

“Our research highlights the importance of using the life cycle assessment tool to better understand how plastics and their alternatives can affect the environment, but I would also like to stress the importance of not overlooking the impact of plastics on marine ecosystems and potential impacts on human and ecological health,” Dr. Meng states.

“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.”

At Interpack 2023, Paul Foulkes-Arellano, circularity educator at Circuthon and non-executive director of Sparxell, told Packaging Insights we are living in a “post-LCA world.”

Life cycle assessments often point to plastics having a far lower emissions rate than alternatives, regardless of recyclability or recycling rates. Foulkes-Arellano, however, says: “An LCA is a snapshot in time — it’s literally looking at one metric, whereas the metrics are four-dimensional if you add time.”

Additionally, a report published last August by Eunomia Research and Consulting demonstrated how LCA designs and methodologies typically produce biased and suboptimal results. 

By Radhika Sikaria