Analysis and sensitivity of land use emissions in biofuel pathways

This paper identified key factors that impacted the life cycle greenhouse gas (GHG) emissions related to land use choices of biofuel feedstocks. The study was developed for the GHGenius model that is used to estimate life cycle emissions of GHGs and criteria pollutants from combustion sources. The study addressed concerns over soil carbon changes related to increased agricultural production for biofuels. The study considered 4 feedstocks: (1) corn; (2) wheat; (3) canola; and (4) soybeans. Different factors related to the application of fertilizer were considered. The environmental impacts of no-till agriculture on soil carbon were examined. The report suggested that default values for soil carbon changes in GHGenius were conservative given the high adoption rate for reduced and no-tillage agricultural management practices. Recommendations included more accurate assessments of soil carbon changes based on actual levels of reduced and no-till managed soils; a recognition that land use emissions from increased crop cultivation will vary throughout Canada; and an acknowledgment that discounting carbon changes in the GHGenius model will increase GHG emissions for biofuel pathways. The most significant issue related to the study was the impact of the conversion of forests and forestland to biofuel feedstock production, a factor which will eliminate the GHG emissions benefits of most biofuels. It was concluded that only 38 per cent of potentially arable land is currently being used, and expansion of some crops is achievable. 10 refs., 23 tabs., 20 figs