Compostable vs. Plastic: A New Study Shows the Real Carbon Footprint

Read full article

by Anthony Keyes, Christopher M. Saffron, Shilpa Manjure, and Ramani Narayan

There’s growing interest in using compostable packaging to replace traditional plastics like LDPE—but how do these materials really compare in terms of carbon footprint and long-term environmental impact? A recent scientific study published in Polymers (MDPI, 2024) set out to answer that question. The researchers found that when we account for how compostable, plant-based materials behave across their full life cycle—including how they’re made and how they break down—biodegradable packaging can significantly outperform fossil-based plastics in both climate impact and pollution risk.

The Full Life Cycle Assessments (LCAs)

The study focused on how Life Cycle Assessments (LCAs)—the main method used to measure the environmental footprint of materials—often fail to give a full picture. Many LCAs ignore one crucial factor: the fact that plants used to produce compostable plastics absorb carbon dioxide as they grow. This is known as biogenic carbon sequestration. When this carbon uptake is left out of the equation, compostable materials can look less favourable than they really are. But when it is included, the difference is dramatic. The study found that compostable bioplastics can result in up to 79% lower carbon emissions than LDPE, when measured using more complete ISO-based methods.

Another key part of the study looked at what happens when packaging reaches the end of its life. Fossil-based plastics like LDPE often end up in landfills or incinerators, and even when they are discarded in nature, they degrade very slowly, breaking down into microplastics that persist in the environment for decades. These microplastics are now found in soil, rivers, oceans, and even inside the human body. Compostable plastics, on the other hand, are designed to fully degrade under the right conditions. When sent to industrial composting facilities, they can break down into carbon dioxide, water, and natural biomass—leaving no toxic residue or microplastic behind.

The researchers also raised concerns about how the European Union’s official LCA standard, known as the Product Environmental Footprint (PEF), currently ignores both biogenic carbon uptake and the long-term risk of microplastic pollution. This means that many compostable and eco-friendly packaging solutions may be undervalued when measured using today’s common standards. The study calls for an update to LCA methods so that they reflect the full environmental benefits of compostable materials.

For businesses and organisations aiming to reduce their carbon footprint, the message is clear: switching to compostable packaging made from renewable sources is a powerful way to cut emissions and avoid contributing to plastic pollution. When properly processed at end of life, these materials don’t just disappear—they return to the earth in a natural, safe way.

This research adds further weight to the case for biodegradable packaging as a credible, low-impact alternative. It reminds us that not all plastics are created equal—and that how we measure their impact matters. With more accurate assessments, compostable packaging can take its rightful place as a key part of sustainable product design.