The Impact of Nitrogen Use Efficiency on Greenhouse Gas Emission in Canola Biodiesel Feedstock Production
The Environmental Protection Agency (EPA) mandated through the second renewable fuel standard (RFS2) that biodiesel meet a minimum threshold requirement (50% reduction) for greenhouse gas (GHG) emission reduction compared to fossil diesel in order to receive monetary incentives for biodiesel feedstock growers (Biomass Crop Assistance Program) and biodiesel processors (Renewable Identification Numbers). A national assessment (LCA) was performed for canola (Brassica napus) biodiesel by EPA and it did meet the minimum threshold requirement. However, while the LCA does consider regional estimates for GHG emission, the estimate of uncertainty associated with canola’s GHG reduction does not reflect variability in feedstock production related soil nitrous oxide emissions due to production region. The authors propose for full GHG reduction potential of biofuels to be realized, LCA results must have regional specificity and should inform regional incentives for growers and processors. The objectives of this work were to determine (1) the impact of NUE on GHG emission from Pacific Northwest canola (2) the impact of nitrous oxide emission estimates for three canola production zones in eastern WA on GHG emission and (3) how canola production regions in Washington State compare to national averages for GHG mitigation. Results from this research may highlight the need for regional assessment/incentive based strategies for maximizing GHG mitigation potential of biofuel feedstocks.