Consequential LCA of two alternative systems for biodiesel consumption in Spain, considering uncertainty

Abstract

Abstract This study assesses possible biodiesel pathways for the Spanish transport sector, representing the current situation. Life Cycle Assessment was carried out for two scenarios: Scenario 1, where 1 MJ of soybean biodiesel was imported from Argentina, and Scenario 2, where 1 MJ of biodiesel from used cooking oil (UCO) was manufactured in Spain. System expansion was performed to include the marginal products involved and additional functions were considered under a consequential approach. Scenario 1 included the production of palm oil in Malaysia (+25.27 g), as the marginal supplier in the global market. This also implied a decrease in the production of soybean meal in Brazil (−3.44 g). In Scenario 2, interactions in the global oil market led to changes in the opposite direction: the production of palm oil decreases in Malaysia (−26.31 g), whereas the production of soybean meal increases in Brazil (+3.58 g). Without considering emissions from Land Use Change (LUC), UCO biodiesel produced in Spain performed better than imported biodiesel from Argentina in all the analyzed impact categories but Global Warming (GW), which was 138.9% lower in Scenario 1, mainly due to the carbon uptake by soybeans in Argentina and palm trees in Malaysia. Since these results could be misleading, GHG emissions from LUC in each country were included. Indirect functions of the expanded systems appeared to have a great contribution in the overall GW impact, especially in Scenario 2. Results show that there are clear environmental benefits arising from the use of UCO biodiesel in Spain to meet the European targets, as compared to the use of imported soybean biodiesel from Argentina. The Monte Carlo simulation for both scenarios also reinforces confidence in the comparative assessment.