Land-use change and valorisation of feedstock side-streams determine the climate mitigation potential of bioplastics

George Bishop,David Styles,Piet N.L Lens

doi:10.1016/j.resconrec.2022.106185

Abstract

Globally, governments have increased their commitment to mitigate greenhouse gas (GHG) emissions. At the same time, the compostable bioplastic market is growing rapidly as many single-use petrochemical plastics are being banned internationally. A prospective consequential life cycle assessment approach was conducted to quantify the environmental envelopes of compostable bioplastic production for the bioplastic value chains to operate within the bounds of climate neutrality. Four indicative feedstocks of (i) lignocellulosic biomass from forestry, (ii) maize biomass, (iii) food waste digestate, and (iv) food waste were evaluated for potential bioplastic production. Upstream and end-of-life emissions for these feedstocks equated to GHG balances of -16.3 to +23.5, 0.3 to 1.0, 1.0 to 4.8, and -0.1 to +0.4 kg CO2 eq. per kg bioplastic, respectively. The scenarios demonstrated that indirect land-use change could have a considerable negative impact on the environmental performance of maize-based plastic, but a positive impact, via terrestrial carbon sequestration, for lignocellulosic-derived plastic (unless increased feedstock demand drives deforestation). Appropriate use of residues and sidestreams is critical to the environmental performance of bioplastics. Efficient utilisation of residues may require decentralisation of bioplastic production and implementation of biorefinery and circular economy concepts.

Highlights

Global life cycle greenhouse gas (GHG) emissions of plastic use were estimated to be 1.7 Gt CO2-equivalent (CO2 eq.) in 2015, projected to increase to 6.5 Gt CO2 eq by 2050 under the current trajectory of increasing plastic production (Zheng and Suh, 2019)
The results for Scenario 1 show that the lignocellulosic biomass, maize biomass, food waste digestate and food waste feedstocks have an “embodied” burden of − 15.8, 1.0, 4.8, and 0.2 kg CO2 eq./kg bioplastic, respectively, arising from upstream and end-of-life emissions (Fig. 6)
As seen in the contribution analysis of the expanded life cycle of one kilogram of compostable bioplastic material (Fig. 6), emission credits from afforestation due to indirect land-use change (iLUC) dominated the lignocellulosic environmental performance, whereas the iLUC emissions from the maize biomass production were the greatest contributor to the environmental impact for that feedstock

Summary

Introduction

Global life cycle greenhouse gas (GHG) emissions of plastic use were estimated to be 1.7 Gt CO2-equivalent (CO2 eq.) in 2015, projected to increase to 6.5 Gt CO2 eq by 2050 under the current trajectory of increasing plastic production (Zheng and Suh, 2019). Bioplastics, and especially compostable bioplastics, are being developed as a more environmentally sustainable replacement for petrochemical plastics (European Commission, 2018) Such plastics are typically made from renewable, bio-based feedstocks and can retain the beneficial material characteristics of petrochemical plastics whilst allowing for a transition towards a circular economy by reducing fossil resource extraction and lowering end-of-life burdens as a result of their com postable nature (Bishop et al, 2021a). This displacement of petro chemical plastics by bioplastics may have the benefit of potentially reducing the global carbon footprint of plastics (Bishop et al, 2021a)

Objectives

Methods

Results

Discussion

Conclusion