In some cases, however, bio-based plastics do not achieve the required lower CO2 release rates in practice. The reasons for this may include significantly smaller production plants and geographically fragmented process steps which involve correspondingly long transport routes. In comparison to this, processes and plants for the production of polyolefins, for example, may be significantly larger and more efficient. If the appropriate growth takes place with locally organized value chains, it may, however, be expected that bio-based plastics really can offer some potential for reducing the release of CO2.
A life cycle assessment (LCA) is more extensive and informative than considering the release of CO2 on its own and its derived global warming potential. This is because in addition to the CO2 footprint, it also covers other factors, such as water pollution, soil acidification, the use of pesticides, and eutrophication. As a result of agricultural activities for producing renewable raw materials, these materials often perform worse in terms of these aspects than petrochemical-based plastics. However, the effects of crude oil extraction should also be included in full in any such comparisons.