Updated Energy Life Cycle Analysis of Soybean Biodiesel Shows Improved Energy Balance

Researchers from the University of Idaho and U.S. Department of Agriculture (both in the United States) recently updated the energy life cycle assessment (LCA) of soybean biodiesel under a United States scenario. The first LCA on soybean   biodiesel was made in 1998 by the National Renewable Energy Laboratory (NREL). This 2009 update (which utilized 2002 data)  has been reported recently in a paper published in the Journal of the American Society of Agricultural and Biological Engineers.  

Life‐cycle analysis (LCA), within the context of biofuels, is a "cradle‐to‐grave analysis" of the energy and environmental impacts of of a biofuel product, from cultivation of the feedstock to final use as fuel. The goal of biofuel-LCA is usually to assess the sustainability of a particular biodiesel product. One parameter that is used in the assessment of a biofuel in the LCA,  is what is known as the "Fossil Energy Ratio" (FER). The FER is defined as  the renewable fuel energy output from one unit of fossil energy input for its production. This parameter is reported to be an index of energy renewability.

Results showed that the FER of soybean biodiesel in the updated LCA, improved to a value of 4.56, compared to the FER value of 3.2 in the 1998 study. This means that the present technology for soybean biodiesel production has a higher energy renewability compared to the technology used in 1998. The increase in FER was attributed to more energy efficient soybean crushing processes and biodiesel production plants, energy-saving practices adopted by farmers and greater soybean yields from improved crops.

Some highlights of the study are: (1) the energy input in soybean agriculture was reduced by 52 per cent, while the energy input in soybean processing was reduced by 58  per cent, (2) The energy input in biodiesel production (by transesterification) was reduced by 33 per cent (per unit volume of biodiesel produced), (4) the overall energy input reduction was 42 per cent for the same amount of biodiesel produced, and (4) the addition of secondary inputs, such as farm machinery and building materials,did not have a significant effect on the fossil energy ratio. Progress in the improvement of energy renewability of soybean biodiesel production was attributed to new production technologies, driven by the increase in demand in soybean biodiesel. Details about the paper can be obtained at the website of the American Society of Agricultural and Biological Engineers (URL Above).

Related information on the Basics of Life Cycle Analysis (LCA):