Environmental and economic impact assessment of biochar-based bioenergy production in Northwestern Ontario, Canada

Abstract

Bioenergy is becoming very popular in Ontario with the 2014 ban on the use of coal in power generation. Biochar is produced as a by-product or a co-product of bioenergy. Past literature shows that if biochar is produced as a co-product with bioenergy from sustainably managed forests and used for soil amendment, it could provide a carbon neutral or even carbon negative solution for current environmental problems. It also shows that detailed life cycle assessment (LCA) and life cycle cost assessment (LCCA) that compares the potential environmental and economic impacts of BBBP system with those of conventional coal-based system is missing. This study fills that gap by assessing environmental and economic implications of a BBBP system in northwestern Ontario throughout its lifecycle using SimaPro® Ver. 8.1, EIOLCA® software and spreadsheet modeling. Under the assumption that only forest residues and/or under-utilized species are used, results show that although a system including biochar based land application consumes 4,847 MJ t-1 dry feedstock more energy than the conventional coal-based system, it reduces the GHG emissions by 68 kgCO2e t-1 dry feedstock during its life cycle. It also improves the ecosystem quality by 18%, reduces global warming potential by 15%, and resource use by 13% but may impact human health by increasing disability adjusted life years (DALY) by 1.7% if biomass availability is low to medium. The economic viability of this BBBP system, within the LCA system boundary, is directly dependent on the costs of pyrolysis, feedstock processing (drying, grinding and pelletization), feedstock collection and the value of total carbon offset provided by the system. The BBBP system is economically viable only in case of high biomass availability within 200km and when the cost of carbon sequestration exceeds C$60 t-1 of CO2e. The environmental and economic impact assessment results developed through this study, can be scaled up to a larger regional scale which is expected to help in reinforcing the confidence of industries and its partners in promoting BBBP systems and the use of biochar as a soil amendment in the region.