Land use change (LUC) analysis and life cycle assessment (LCA) of Brazilian soybean biodiesel

Abstract

Biodiesel is an alternative to tackle global warming, especially for reducing greenhouse gases (GHG) emissions when replacing fossil fuels. However, it can compete for land with food production. Brazil is a global player on soybeans farming and most of the biodiesel produced in the country comes from it. This work proposes a new approach to evaluate its impact, associating land use change (LUC) analysis with life cycle assessment (LCA) in a representative Brazilian soybeans farming zone. LUC assessment used Landsat satellite imagery analysis from the years 1993 and 2013, and intergovernmental panel on climate change (IPCC) guidelines to estimate GHG emissions. LCA was based on field data collection processed with SimaPro^®. Results show that the increment on annual GHG emissions per hectare, derived from the apportioning total emissions for the period studied, was 50.16 kg CO₂ eq ha⁻¹ y⁻¹. From this increment, 97.1 % come from LUC, being the largest share from converting pastures to soybeans farming (81.2 % of the total emissions). However, in the area, a large share of converted pastures are degraded, acting as source of emissions, not as sink as considered by IPCC. At the same time, practices like no-tillage make soybeans a carbon sink. Therefore, results could change if alternative approaches were to be adopted, being a challenge for future work. Therefore, when considering biodiesel from soybeans, a close regard to local land use dynamics is essential to evaluate impacts. Besides, promoting more efficient use of land already cleared with the goal to avoid deforestation can turn biodiesel into a sustainable renewable energy source.