The Biodiesel Factor
Preceding the development of biobased PG was the broad effort in the 1990s to replace petroleum products with fuels from renewable sources, such as ethanol as a supplement for gasoline. A prime target was a biobasedreplacement for diesel fuel. Because diesel yields better mileage than comparable gasoline engines, it has long been popular for long-distance transportation — more than 90 percent of freight is shipped in diesel-powered trucks, trains and boats.
Its popularity presented an opening for development of biodiesel alternatives produced from soy and other oily plant and animal sources. According to the National Biodiesel Board, an industry trade group, some 112 million gallons of biodiesel were sold in the United States in 2005; with some 150 biodiesel plants in operation in 2011, the figure was 1.1 billion gallons.
And, biodiesel production has a byproduct — the sweet, colorless, syrup-like liquid called glycerol.
“The early 2000s led to a ‘glut’ of glycerol research,” Zacher notes. “People thought biodiesel would saturate the glycerol market. A ‘free’ feedstock makes every idea look economical, but it turned out that glycerol was never going to be free. Only economically sensible ideas would prevail.”