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Plastics made from renewable raw materials are often considered a green alternative to fossil-based plastics. However, according to a study from the  – conducted in collaboration with Aalto University, the Natural Resources Institute Finland (Luke), VTT Technical Research Centre of Finland, and the University of Lapland – the environmental impact of bio-based plastics can be surprisingly high and in some cases even greater than those of their fossil counterparts.

Life-cycle assessment reveals the challenges associated with producing bio-based raw materials: cultivation and processing can, for example, generate air and water emissions, increase pressure on land use, and reduce biodiversity if forests are cleared for crops.

‘From an environmental perspective, the key is that materials are suitable for their purpose and designed to minimise waste. In addition to carbon footprint, we must also consider impacts on biodiversity, land use and resource sufficiency,’ says Research Professor Hannu Ilvesniemi from Luke.

Bio-based plastics are typically produced from materials such as vegetable oils, starch, or lignin. However, their mechanical strength does not always match that of fossil-based plastics. 

‘However, we identified promising solutions in our research: by combining different raw materials, it is possible to achieve both sufficient performance and reduced environmental impact. One option is composites, made by blending bio-based and fossil-based components,’ says Assistant Professor of Polymer Technology Jukka Niskanen from Aalto University.

In some cases, combining a bio-based plastic with a bio-based filler may be more environmentally beneficial than a fully bio-based plastic. Similarly, blending fossil-based plastics with bio-based fillers can also reduce environmental impacts. 

‘Long-lasting use of plastics, along with reuse and recycling, can significantly reduce environmental burdens. New composites – for example those incorporating starch or biochar – can at the same time improve material performance and lower the carbon footprint,’ Ilvesniemi adds.

However, recycling composites is challenging, which calls for new approaches in product design and recycling systems. According to the researchers, a sustainable plastics transition requires close cooperation between research, industry and policy – and careful assessment of the entire value chain to determine when bio-based solutions genuinely reduce environmental impact.

Coordinated by Aalto University,  project brings together the University of Lapland, the Natural Resources Institute Finland (Luke), VTT Technical Research Centre of Finland, and several industry partners. Funded by the Strategic Research Council at the Academy of Finland, the project combines materials research with life-cycle assessment, circular economy solutions, and business perspectives.