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Dealing with Bio-Diesel Waste

February 6, 2008


Waste byproducts are a challenge for any industry. When waste in one industry can be used as a base resource in another industry, the problem shrinks and profits improve. It also increases the efficiency of the system. In a recent post, I talked about the potential of using algae to produce bio-diesel [The Potential of Pond Scum]. One of the oft-leveled criticisms about producing bio-diesel is that it is inefficient. That’s because a robust after-market for refinery byproducts doesn’t currently exist. There are, however, a number of people working to solve that problem [“Cooking Up More Uses for the Leftovers of Biofuel Production,” by Hillary Rosner, New York Times, 8 August 2004].

“The baking tins and muffin cups lining the countertops in a corner of Ronald Holser’s cluttered laboratory were filled with curious substances resembling angel food cakes and loaves of bread. But Mr. Holser did not advise eating them. The concoctions were prototypes for biodegradable weed barriers and sticky films intended to hold grass seeds on the ground long enough to germinate. If Mr. Holser, a research chemist, and his colleague Steven F. Vaughn, a plant physiologist, are successful, they will have found more than ecologically friendly ways to fight weeds and grow grass. They will have found innovative uses for a byproduct of the production of biodiesel fuel, glycerol. This, in turn, could help transform the biodiesel industry into something that more closely resembles the petroleum industry, where fuel is just one of many profitable products. ‘Just like petroleum refineries make more than one product that are the feedstock for other industries, the same will have to be true for biofuels,’ said Kenneth F. Reardon, a professor of chemical and biological engineering at Colorado State University in Fort Collins.”

One of the primary byproducts of the production of bio-diesel is glycerol (glycerin). For every gallon of bio-diesel refined, a pound of glycerol is produced. Although there are some uses for glycerol in today’s economy, there is nevertheless a glut of glycerol available.

“Glycerol is used in a variety of products, including foods, soap and dynamite. But as biodiesel fuel production in the United States has risen, the market for glycerol has become saturated. If scientists like Mr. Holser, who works at the United States Department of Agriculture’s research center in Athens, Ga., and Mr. Vaughn, who works at the department’s National Center for Agricultural Utilization Research in Peoria, Ill., can expand the number of valuable uses for the syrupy liquid, biodiesel makers could sell their glycerol instead of paying someone to haul it away.”

I’m not a chemist, but I’m sure that different sources of bio-diesel (e.g., corn, rapeseed, and algae) produce different byproducts in different amounts. That leaves lots of room for researchers to experiment with the various materials.

“Glycerol … is not the only byproduct of biofuel production that is the subject of experiments. Scientists are also looking at profiting from the leftovers from the production of corn ethanol and cellulosic ethanol, made from materials like switch grass, corn husks and prairie grass. Around the country, scientists, entrepreneurs and venture capitalists are becoming increasingly interested in making more than fuel out of the raw materials for biodiesel fuel and ethanol. ‘The opportunity, as we think about increasing our consumption of biologically derived fuels, is to consider what besides fuels can we make,’ said Erik Straser, general partner of MDV Mohr Davidow Ventures, a venture capital firm in Menlo Park, Calif. Some researchers, like Mr. Holser, are simply trying to find new uses for the regular byproducts of biofuels: distillers’ dry grain from corn ethanol and lignin from cellulosic ethanol.”

Lignin, according to the article, is another large byproduct of refining bio-diesel.

“In the foothills of the Rocky Mountains, not far from the Coors brewery in Golden, Colo., PureVision Technology is making lignin. A natural compound that helps provide strength and rigidity in plants, lignin makes up 15 to 25 percent of most plants. Most plans for cellulosic ethanol processing call for burning the lignin to generate steam and heat to run the process. As a fuel, lignin is worth around $40 a ton. PureVision has devised a way to make a different form of lignin — one with a molecular composition that could make it an attractive material for a variety of industrial products like glues, sealants and detergents. Ed Lehrburger, PureVision’s founder and chief executive, said he thought his lignin could sell for $300 a ton or more. Mr. Lehrburger said his company was collaborating with a wood and paper products manufacturer that is interested in using the lignin for a biobased glue for its laminates, plywoods and other products. ‘Lignin is going to be one of the big drivers of the switch from oil-based to biobased products,’ Mr. Lehrburger predicted.”

It turns out that how you refine bio-diesel changes the byproducts produced during the process. Researchers, therefore, are looking at different refining methods at the same time others are experimenting with what can be made of the various byproducts.

“In Ames, Iowa, Victor Lin has created a technology that changes the production process for biodiesel. Among other attributes, Mr. Lin’s invention yields a higher quality form of glycerol, which could be more easily converted into useful industrial materials. A chemistry professor and the associate director of the Center for Catalysis at Iowa State University, Mr. Lin is … created a catalyst that is safer and easier to use than the one commonly used now, reducing the cost of producing biodiesel and its impact on the environment (requiring less water, for instance). Dr. Lin and his colleagues are trying to turn the resulting glycerol into a substance called 1,3 propanediol, or PDO, the base material for a substance used in upholstery, carpets, clothing and other applications. DuPont uses PDO to make its Sorona line of fabrics. … In another lab at Iowa State, Robert C. Brown is using distillers’ dry grain —a main byproduct of corn ethanol that is largely sold as animal feed — to produce hydrogen and a compound called PHA. Mr. Brown hopes his version of PHA, which is biodegradable, could be used for surgical gowns and gloves that must now be disposed of as medical waste.”

The research into what kinds of byproducts can be produced must be more than matched by what kinds of useful products could be part of the after market.

“Despite the many uses for byproducts, the biorefinery model is more difficult than it may seem. ‘The dream is the multiproduct biorefinery,’ said Jim McMillan, manager of biorefining process research and development at the National Renewable Energy Laboratory in Golden, Colo. ‘The challenge is that the market for the fuels is like two orders of magnitude bigger than for even a fairly big chemical’ that could be produced alongside the fuel.”

Without a working “biorefinery model,” even a modest switch from petroleum to bio-diesel products will create an enormous amount of waste (with associated disposal challenges and costs), not to mention the continued rise in food prices as the demand for grains increases.

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