Environmental Impact of Oil Crops and Biofuels

Studies on Life Cycle Assessment (LCA) of bioenergy chains based on dedicated crops in temperate climates show that biodiesel scenarios are generally less impacting than other possible energy chains, both in 1st generation and in 2nd generation biofuel settings. Considering the cropping techniques described for large scale farming in the previous chapters, a comparison of the environmental impacts of oil crops “from cradle to farm gate” was performed using the LCA methodology. More to this, a family farming scenario leaving manpower impact apart was calculated for comparisons with large scale farming systems. The phases and methods of LCA are described; a “cradle to farm gate” approach was adopted in the impact assessment of the oil crops. Results were standardized, i.e. reported in kg of equivalent reference substance, and normalized, i.e. weighted on the average level of emissions of one world inhabitant. Results are displayed both on both a surface (hectare) and energy (GJ) basis. The category most affected by agricultural processes is eco-toxicity of marine waters, although the primary cause of this emission is P fertilizer manufacture, which is upstream cropping. On a surface basis, the most impacting scenario was sunflower, in all considered categories, and in general both annual crops (sunflower and soybean) showed similar results. On an energy basis, the most impacting scenario was still sunflower under all impact categories, but the remaining scenarios show significant differences in comparison with the analysis on hectare basis: soybean showed emissions levels 40 to 60% lower than sunflower, although only one third of the emission per ha was allocated to oil production, the rest being spent for protein. Perennial crops showed high benefits respect to annual ones also on energy basis. A last topic addressed in this chapter is indirect land use change (ILUC). To convert land use change into consequent GHG emissions, a conversion factor must be applied. The level of GHG emissions associated with land use change will vary depending on previous land use; therefore, there is a wide range of possible conversion factors. GHG emissions are not the only impact of ILUC. Biodiversity is also adversely affected by land conversion in the form of ecosystem degradation and habitat loss. Biodiversity and ecosystems–and the services they provide are closely connected to each other and to the climate system. Biodiversity is crucial for both mitigation of and adaptation to climate change. However, the substitution of many food crops (e.g., cereals) with energy crops often requiring less fertilizers and pesticides, determines a net benefit in terms of biodiversity. Another way of limiting ILUC consequences would be shifting to second generation biofuels, which are now on the eve of diffusion in advanced countries.