Biodiesel boom creates glut of glycerin
A waste byproduct is converted to environmentally friendly antifreeze.
Corn-based ethanol gets a lot of attention these days, but industry runs on diesel. The biodiesel industry hopes to provide a “green” alternative to petroleum-based diesel by squeezing fuel from waste materials and plants. The idea’s starting to catch on; sales shot up from 5 million gallons (gal) in 2001 to 250 million gal in 2006, and Virgin Trains launched Europe’s first biodiesel train this month.
But as researchers hunt for ways to turn more unwanted resources like turkey innards or inedible plants into fuel, the industry has created a waste problem of its own: glycerin (also known as glycerol) is piling up at an enormous rate. The chemical reaction that makes biodiesel creates about 0.8 pounds (lb) of glycerin for each gallon of fuel. That added up to about 200 million lb of glycerin in 2006—or about half of total U.S. glycerin consumption, according to the National Biodiesel Board.
Galen Suppes, a chemical engineer at the University of Missouri Columbia saw a big opportunity. Suppes won a Presidential Green Chemistry Challenge Award in 2006 for pioneering a process that turns glycerin into propylene glycol. Supplies of propylene glycol—used in cosmetics, food, and pharmaceuticals and as nontoxic antifreeze—are tight. Global demand for the chemical, which is normally made from petroleum, exceeds 3 billion lb per year, according to Dow Chemical Co.
“In a nutshell, my motivation is a balance between being environmentally friendly and economically feasible,” Suppes says. Over the past several years, Suppes and the company he cofounded, Renewable Alternatives, have taken the award-winning chemistry from the lab to industrial application.
In 2002, Suppes attended a brainstorming session in New Orleans on the future of biofuels. When the National Biodiesel Board mentioned that tons of glycerin were starting to pour out of biodiesel plants, Suppes took notice. Sure enough, a glut of refined glycerin soon caused prices to plummet from $1.10/lb to 25¢ or less. Today, biodiesel refineries practically give the stuff away just to get it out of their storage tanks. Last year, Dow, which once held a virtual monopoly on glycerin, closed its plant in Freeport, Texas.
Researchers started looking for ways to use glycerin; some experimented with adding it to animal feed or even spraying it on dirt roads to keep dust down. “Smaller producers were even having to landfill it,” says William (Rusty) Sutterlin, CEO of Renewable Alternatives.
Suppes looked for a way to turn the cheap resource into a useful product. He realized that simply stripping one hydroxyl group from glycerin would yield propylene glycol, and his team set out to improve on the existing conversion process. In 2003, he teamed with Sutterlin, then a Ph.D. student in chemistry at the University of Missouri Columbia.
At first, the company focused strictly on creating antifreeze made of glycerin mixed with propylene glycol. But industry contacts soon led them to aim for pure propylene glycol. Their process now achieves more than 99.8% purity, which means their product can be used as industrial feedstock and as antifreeze.
“One of the greatest environmental impacts we can have is replacing ethylene glycol as antifreeze,” Suppes says. Even though crop production may be too limited for biofuels to be the ultimate energy solution, he feels good about developing renewable processes that reduce dependence on finite petroleum resources, he says.
Renewable Alternatives licensed the patented process to Washington-based Senergy Chemical. Senergy has partnered with a chemical plant in an undisclosed location in the Southeast that is currently retrofitting for the process and is expected to start producing propylene glycol at the end of the year, says Senergy president Mark Tegen.
Big players in the agrochemical industry like Dow and Archer Daniels Midland Co. (ADM) smell the profit potential and are scrambling to follow suit. In 2005, ADM announced it will build its own plant to make propylene glycol and ethylene glycol from corn and soybeans using its own technology.
Sutterlin and Tegen say that competition is stiff, but they have the upper hand. “We will probably be the first to market,” Sutterlin says. And other processes may not achieve the same high purity because they make more ethylene glycol as a byproduct, Tegen adds.
Glycerin “is an advantage for [the] biodiesel industry” now, says Steve Howell, technical director for the National Biodiesel Board. With another renewable product to sell, “biodiesel has a one-two punch for substituting petroleum-derived chemicals,” he adds.
(For more on biofuels, visit a blog with news and observations from Brazil about biofuels research from ES&T’s Erika D. Engelhaupt and C&EN’s Stephen K. Ritter at http://cenbrazil.wordpress.com).
