Unraveling the climate neutrality of wood derivatives and biopolymers

Abstract

Bio-based materials are widely perceived as climate-neutral. To validate this perception, we conduct a lifecycle scenario analysis for biopolymers, namely lignin and cellulose nanofibrils, derived from wood. The resulting carbon footprints vary between climate-positive and climate-negative values: −2.06 to 14.95 kg CO2 eq. per kg for lignin and −1.57 to 12.20 kg CO2 eq. per kg for cellulose nanofibrils. In contrast, the carbon footprints for conventional fossil-based polymers have lower variability but do not exhibit climate positivity. This variability in carbon footprints is a result of: (i) the specificities of the material lifecycle, i.e., the extraction processes, duration of the use phase, and end-of-life management; (ii) accounting of biogenic carbon; (iii) biodegradability. In order to leverage the potential climate benefits of bio-based materials, efficient production pathways have to be established, their duration of use should be maximized, and EoL mismanagement leading to unintended greenhouse gas emissions should be avoided.