By Amy Woolf
A late 2009 study found that biodiesel gives more energy back to the earth than it takes in its synthesis. The study, done by the U. S. Department of Agriculture and the University of Idaho, found that for every unit of energy that it takes to produce biodiesel, 4.5 units is returned to the earth. When conducting this study, the researchers took into account all aspects of biodiesel synthesis and mathematically compared it to the process that yields petroleum.
The study was based on biodiesel synthesized from soybean oil, which is the resource used most commonly to make biodiesel. Energy is saved because the main source of energy used to grow soybeans is solar. The modern soybean also needs fewer pesticides than in the past and it also has the ability to grow in fields that are not as thoroughly tilled as previously needed, which saves energy. Biodiesel can also be synthesized from recycled resources, like used cooking oil, which would raise the positive energy outcome even more.
There was a similar study done by the USDA in 1998 that also showed a positive energy balance for biodiesel – 3.2 units as opposed to the 0.84 units from petroleum diesel. The energy efficiency of biodiesel has improved while the efficiency of petroleum diesel remains about the same.