Life-cycle assessment of biodiesel versus petroleum diesel fuel

The US Department of Energy's Office of Transportation Technologies, DOE's National Renewable Energy Laboratory, the US Department of Agriculture's Office of Energy and Ecobalance are carrying out a comprehensive life cycle assessment (LCA) of soy-based diesel fuel (biodiesel) to quantify the environmental aspects of the "cradle-to-grave" production and use of biodiesel. The purpose of the project is to produce an analytical tool and database for use by industry and government decision makers involved in alternative fuel use and production. The study also includes a parallel effort to develop a life cycle model for petroleum diesel fuel. The two models are used to compare the life cycle energy and environmental implications of petroleum diesel and biodiesel derived from soybean. Several scenarios are studied, analyzing the influence of transportation distances, agricultural practice and allocation rules used. The results of an LCA such as this are strongly influenced by decisions made at the study outset, related to scoping, modeling and methodology. Objectivity as well as acceptance of the results depend upon careful definition and consideration of such issues. This paper communicates the project scoping decisions which have been made in response to a series of stakeholder peer reviews.