Rising soybean yields have had a significant impact on biodiesel’s energy efficiency. In fact, new research from the University of Idaho and the USDA indicates that the fossil energy ratio (FER) of soybean-based diesel could reach 4.69 units of energy for every unit of fossil energy consumed over its life-cycle when average soybean yields reach 45 bushels per acre. This is projected as early as 2015.
This shows how much crop yields impact the efficiency of biodiesel production. In 1998, J. Sheehan, then at the Department of Energy’s National Renewable Energy Laboratory, found that biodiesel yielded 3.2 units of energy for every unit of fossil energy it required over its life-cycle compared to petroleum diesel which yielded just about .84 units of energy per unit of fossil energy consumed. The average soybean yield at that time was 38.9 bushels per acre.
The new study also points out that the increased use of no-till and transgenic soybeans (which have had a major effect on pesticide use) have further reduced fossil fuel requirements.
If you’re a soybean farmer, share this study with your friends as well as skeptics and let them know that biodiesel’s energy efficiency, like fine wine, keeps getting better and better. You can read “Energy Life-Cycle Assessment of Soybean Biodiesel,” A. Pradhan, et al at www.usda.gov/oce/reports/energy/ELCAofSoybeanBiodiesel91409.pdf.