Assessing the energy potential of agricultural bioenergy pathways for Canada

Abstract

We assessed agricultural bioenergy pathways using existing and newly developed life cycle energy analyses so as to compare the potential of these pathways to replace fossil fuel in Canada. Energy gains after subtracting life cycle fossil energy inputs (Eg) and the ratio of fuel energy to life cycle fossil energy input (ER) were calculated. Results varied widely, reflecting differences in regional yields and study assumptions. Grasses and coppiced willow processed to electricity and heat exhibited Egs of 29–117 GJ ha-1 yr-1 and ERs of 4-17. These crops processed to lignocellulosic ethanol showed Egs of 22–114 GJ ha-1 yr-1 and ERs of 5–13. Grain ethanol and oilseed biodiesel showed Egs from -15 to 32 GJ ha-1 yr-1 and ERs from 0.8 to 3.7. Assuming 20% of Canada’s cleared agricultural land could be dedicated to annual biofuel crops, grain ethanol or oilseed biodiesel could displace up to 10 or 50%, respectively, of national road gasoline or diesel demand. If instead 40% of cleared agricultural land could be dedicated to perennials, the feedstocks could displace up to 52% of road gasoline demand if proc essed to lignocellulosic ethanol or 100% of utilities’and industries’fossil fuel demand for electricity and steam production. Our analyses showed that a goal of fossil fuel displacement favors the production of perennial crops for electricity and heating. Key words: Biomass, life cycles, oilseed, grain, grass, coppice