Nitrous Oxide Emissions from Agricultural Soils: Effects on the Environmental Profile of Soybean Biodiesel

PIASTRELLINI, ROXANA; ARENA, AP; CIVIT, B

chacras de coria

Conferencia; V Conferencia Internacional sobre Análisis de Ciclo de Vida; 2013

UTN FRM - Red Iberoamericana de ciclo de vida

Purpose. Nitrous oxide (N2O) emissions from agricultural soils are the greatest source of greenhouse gas emissions associated with bioenergy crop production. At present, the most widely accepted methodology to estimate these emissions in biofuel life cycle studies is that proposed by the Intergovernmental Panel on Climate Change (IPCC); however, the emission factors used have large uncertainty ranges. In Argentina?s Pampas region, field measurements suggest that this methodology may overestimate N2O emissions. The European Commission?s Joint Research Centre (JRC) suggests the adoption of the model developed by Stehfest and Bouwman (2006) to obtain an approximation of the real values of emission. The purpose of this study is to analyze the influence of N2O emissions on the environmental profile of soybean biodiesel produced in Argentina. A sensitivity analysis was carried out to evaluate to what extent variations of N2O emissions originating from agricultural soils affect the results. Methodology. N2O emissions were estimated following the methodology suggested in the IPCC Guidelines (2006), including the evaluation of default emission factors and both ends of the uncertainty range. In addition, the JRC method was applied, bringing to bear edaphoclimatic and crop conditions. The case study focuses on the Argentine region of the Pampas. The functional unit defined is 1 MJ of energy obtained from soybean biodiesel. The impact assessment stage of the life cycle contemplates the categories included in the EDIP method (2003). Results. A significant influence of N2O emissions is observed on the environmental profile of soybean biodiesel, with variations in the results of 35% in the Global warming category, 8% in Ozone formation and 5% in Acidification and Eutrophication. The results obtained with the JRC methodology are considerably higher than the field measurements reported in the literature and the values estimated with the IPCC method. Conclusions. Among the methods studied, the JRC proposal seems to be the least favorable for application in soybean biodiesel production in Argentina. Keywords: nitrous oxide, agricultural soils, soybean biodiesel, environmental profile