The impact of increased biodiesel production on the greenhouse gas emissions from field crops in Canada

Greenhouse gas (GHG) emissions associated with the production of the 21 major field crops in Canada were 16.8 Tg CO2e of N2O and 17.2 Tg of fossil fuel CO2 in 2006. The mean GHG emission intensity on an area basis for these crops was 1.0 Mg of CO2e per ha. On a dry matter (DM) basis, the mean GHG emission intensity was 0.33 Mg of CO2e Mg−1 DM. For western Canada, the GHG emission intensity was 0.35 MgCO2e Mg− 1 DM and 0.30 MgCO2e Mg− 1 DM for eastern Canada. The sensitivity of the GHG emissions to crop-specific GHG emission intensities was demonstrated by examining two biodiesel scenarios. The biodiesel share of the diesel fuel blend was 2% in the first scenario (B2) and 5% in the second scenario (B5). The increased feedstock was assumed to come from canola and soybeans. The B2 scenario increased the emission intensity for western Canada to 0.38 MgCO2e Mg− 1 DM and the B5 scenario to 0.43 MgCO2e Mg− 1 DM. Neither scenario had any appreciable effect on the magnitude of the emission intensity for eastern Canada. The GHG emissions from the canola-dominated western Canadian field crops were increased by the B2 and B5 fuel blend scenarios. In the soybean-dominated east, the two scenarios resulted in decreased GHG emissions from field crops. Canola-based biodiesel potentially eliminates more petrodiesel CO2 emissions than soybean biodiesel. However, for both scenarios, the net potential GHG reductions (petrodiesel offset plus change in GHG emissions from field crops) were 2.60 MgCO2e ha−1 of additional oilseeds in the east and 0.94 MgCO2e ha− 1 in the west. The higher meal by-product from soybean oil meant a smaller loss of livestock feed for eastern Canada.