The direct environmental impacts of biodiesel have been investigated in various attributional Life Cycle Assessment (LCA) studies. However, the production of biodiesel is strongly intertwined with other uses of land like nature conservation and supply of food. Moreover, the increased production of biodiesel causes additional co-products such like oil meals and glycerine, which affect the production of alternative products on the world market.

In this context, prospective scenarios have been developed in cooperation with the Federal Office for Agriculture and assessed by means of a consequential LCA. In contrast to attributional LCA, the consequential approach uses system enlargement to include the marginal products affected by a change of the physical flows in the central life cycle.

In sum, the majority of the scenarios show a trade-off between minimizing GHG emissions and having a positive environmental LCA. The included emissions from land use change are most critical for GHG emissions (i), whereas the results for UBP are primarily dominated by increased oil crop cultivation (ii).

(i) An increased production of rape oil also increases the production of press cake. This decreases the demand for Brazilian soy bean meal, which is the marginal protein meal on the global market. Primarily due to the related, avoided transformation of rain forest, this causes a significantly benefit for the net GHG emissions.

(ii) An increased production of RME causes a direct and indirect increase of global vegetable oil production. This has a negative influence on many environmental impact factors and also on the total environmental impacts, because agricultural production of vegetable oil is associated with higher environmental impacts than the production and use of fossil fuels.

In general this study shows the strong dependence of the results on the replacement options. If, for example, the marginal product on the world market for protein meal would switch from soy bean meal Brazil to soybean meal USA, the net GHG emissions for the Swiss production of RME would increase remarkably. From a long-term environmental perspective it seems to be therefore wise, to focus the production of agro-biofuels on feedstock’s, that are decoupled from the global food and feed markets.

Contact: Jürgen Reinhard