Patrick Brassard, Stéphane Godbout, Lorie Hamelin

The development of bioeconomy needs to accelerate in order to get rid of fossil fuels and products. The production of bio-based products and renewable energy sources from the thermochemical conversion of biomass can be a sustainable alternative. Pyrolysis is one of the thermochemical processes that can convert biomass into liquid (bio-oil), solid (biochar) and gaseous (non-condensable gases) products. Process operational parameters and biomass type must be selected appropriately to obtain the desired products yields and properties. Before deciding to apply the technology on a large scale, it is necessary to determine the environmental performance of the process. This can be done through the life cycle assessment (LCA) method. This study presents a consequential LCA framework to quantify the environmental performance of a pyrolysis biorefinery by including in the boundaries the current use of biomass and the marginal technologies that are expected to be replaced by pyrolysis co-products. Results obtained from this method are intended to provide answers to decision-makers towards investments in the low fossil carbon future. The proposed LCA framework was applied to a case study for the use of primary forestry residues (PFR). Results showed that as compared to the reference scenario in which PFR are left on soil to decay, pyrolysing PFR to biocrude oil, wood vinegar, biochar and gas presents trade-offs in six out of the 16 impact categories studied. These results highlighted that the biomass feedstock supply, the pyrolysis technology, the co-products yields, properties and uses, as well as the choice of marginal technologies have an influence on the environmental performance of pyrolysis biorefineries.