Biofuel Blends Are Often Inexact

Accurate Biodiesel Blending Poses a Problem for Many Distributors

Feb 27, 2008

Biodiesel sold to many consumers may be inaccurately blended and not contain the amount of biofuel advertised by its labeling.

Researchers from Woods Hole Oceanographic Institution (WHOI) have found that biodiesel fuels purchased from many small distributors are inaccurately blended and don't contain the specified amount of biofuel.

In a statement announcing the release of the study, Woods Hole Marine Chemist Chris Reddy says, "Biodiesel is a great product if used properly, and it could turn out to be an important alternative fuel. There is a lot of good feeling about biodiesel, but if we are going to sell it, we have to make sure what is being sold is accurately prepared. It is a matter of credibility and consumer confidence."

What is Biodiesel? - Biodiesel is a chemically treated mixture made of vegetable oil and animal fat. Unadulterated or pure biodiesel fuel is labeled at the pumps as B100. A commonly sold blend of 20 percent biofuel and 80 percent regular diesel fuel known as B20. Biofuel advocates promote the product on the basis of its reduced pollution and toxicity.

While studying the effects of biodiesel on the marine environment, Reddy and his fellow researchers found that there was wide variation in the accuracy of blends sold by a dozen different retailers. A biofuel range of 10 to 74 percent was found present in fuel labeled B20, with only 10 percent of the samples falling within standards set by the Department of Defense.

Why is Accurate Blending Important? - Poorly blended biodiesel may stratify into various viscous layers. In colder climates, the thicker layers of the fuel can congeal and plug fuel lines, injectors or filters, stopping an engine. Federal and state tax incentives are based on the amount of biofuel placed in the market. Companies that over report the amount of biofuel present in an advertised blend defeat the purpose of the tax credit and reduce government revenues. Biofuel advocates are concerned that inaccurate blending and poor press reports will lessen consumer confidence in their fledging industry.

Is There a Common Standard for Biodiesel? - Nationally, there is no enforceable standard for blending biodiesel. The current BQ-9000 biodiesel certification program standards in place are strictly voluntary. Earlier studies point out that larger fuel distributors even have a hard time correctly blending the new style fuel.

Reddy's research group used precise radiocarbon measurements to determine the composition of biofuel blends. Petroleum derived fuel contains no radiocarbon making accurate measurement of the remaining biofuel balance easy. This method is likely too expensive for use as a routine aid in biofuel blending.

Crude oil has exceeded $100 per barrel and biodiesel is now cheaper to purchase than conventional diesel fuel in some locales. Agencys like NOAA have started green ship initiatives. The biodiesel industry is concerned about public perception for their products and they are working to control the blending problem. Reddy and his colleagues report is being published by the journal Environmental Science and Technology in April of 2008.

The copyright of the article Biofuel Blends Are Often Inexact in Energy Conservation is owned by Alan Sorum. Permission to republish Biofuel Blends Are Often Inexact in print or online must be granted by the author in writing.