Constance Ißbrücker, Head of Environmental Affairs at European Bioplastics e.V.

Life cycle assessment (LCA) has evolved to be the preferred tool to assess the environmental sustainability of certain products and materials. Recently it has also been used with great enthusiasm to compare bio-based with fossil-based plastics. It seems to be an easy instrument to draw conclusions on certain advantages or disadvantages of both material groups. However, there are quite some hurdles to overcome if you do not want to end up comparing apples with oranges again. 

There are several aspects to which attention must be paid in order to guarantee a fair comparative assessment. Fossil-based plastics have experienced many decades of continuous, often heavily subsidised, process improvements, whereas most bio-based alternatives are still at the beginning of their maturity/optimisation curve. Therefore, comparing fossil-based with bio-based plastics is comparing mature and immature production systems. Future improvements in terms of feedstock sourcing, production, conversion, and end-of-life options need to be considered and assessed by appropriate assumptions and modelling approaches.   

Additionally, it is often assumed that the applied inventory data of bio-based and fossil-based materials are comparable, but currently there is in fact no real level playing fieldFossil- and bio-based plastics datasets should be brought to the same level of quality in terms of their completeness, system boundaries, regional scope, and, of course, transparency. 
It is one of the inherent advantages of bio-based materials that they are produced from annually renewable feedstock, such as corn, sugarcane, or wood. Thus, CO2 is taken up from the atmosphere, and the biogenic carbon is locked up in the bio-based product. At the product’s end of life (i.e. when it can no longer be recycled), the carbon re-enters the natural carbon cycle via incineration or composting, thereby closing the material carbon loop. 

Bio-based plastics are independent of fossil resources and do not contribute to harmful environmental effects connected with the exploitation of fossil raw materials such as crude oil. Effects of the latter are, interestingly, hardly considered in LCA data modelling. In contrast to certain possible negative indirect effects connected with the sourcing of renewable feedstockNo doubt, it can make sense t