Bioplastics are gaining attention as a means of reducing fossil resource dependence. Most bioplastics differ from fossil-based plastics in molecular structure, and therefore in terms of properties and durability. Still, the life cycle environmental performance of bioplastics has attracted limited attention in research. The purpose of this study is therefore to examine the importance of applying a life cycle perspective and identify key considerations in the environmental evaluation of bioplastics and bioplastic products under development.

The climate impact of the life cycle of an engine component storage box currently made of the fossil-based plastic acrylonitrile butadiene styrene (ABS) is compared to a hypothetical case study, based on laboratory observations, of the same box produced from a blend of polycarbonate and the bioplastic polylactic acid (PC/PLA) and a box made of biopolyamide (PA1010). The comparison is conducted with a cradle-to-grave attributional life cycle assessment. The functional unit of the study is five years of service life, which reflects the required function of the storage box.

Whereas the climate impact of the production of the different plastic materials differ only slightly, the PC/PLA engine component storage box was found to have a significantly higher climate impact that the ABS and PA1010 boxes when the whole life cycle is taken into account. The dominant contributor to climate impact is premature material deterioration due to humidity and heat during service life, which prevents the product from fulfilling the required function. Two other influential aspects are the possibility of material reuse and the share of fossil or biogenic carbon in the product. Production of plastic materials and boxes, and transport distances, are of less importance.

Results demonstrate the high significance of including service life and potential material deterioration when bioplastics and fossil-based plastics are compared. Our findings underline the importance of applying a life cycle perspective and taking into account the intended application and function of bioplastics as part of their development and environmental assessment.