National Biodiesel Surge Creates Bittersweet Co-product with Glycerol

Crude glycerol is not a valuable product and currently sells for about 1 to 2 cents per gallon. For every 100 pounds of biodiesel produced, 10 pounds of glycerol is also created. Although it is possible to refine crude glycerin into a marketable product, it is a process that is beyond the reach of most small-scale producers due to the large investment in technology necessary for the refining process.

Finding a large-scale use for crude glycerin would help lighten the load of growing supplies and give the biodiesel industry more revenue. Not only is it essential to find economically viable refining process, it is also important for the environment.

iCAST, the International Center for Appropriate and Sustainable Technology, is helping farmers grow their own fuel. Part of this work has brought the company to research the uses and markets for biodiesel co-products.

Traditionally, glycerin has been used to produce nitro-glycerin and soap. But crude glycerin can also be burnt, composted or fed to ruminants. Research on turning glycerin into an alternative to antifreeze is also within grasp.

Burning glycerin for heat and power can render positive effects, however, temperature is a significant concern. Burning glycerin at temperatures between 200 and 300°C (392-572°F) emits toxic acrolein fumes so temperatures beyond 1,000°C (1832°F) are necessary.

As a sugar, glycerin can be a considerable addition to compost. This is a much simpler option. However, it is important to make sure the glycerin does not cut out oxygen and negatively affect pH, which harms the composting bacteria. Glycerin is also a liquid and therefore hard to contain. Since it can be harmful to ground and surface water, it is vital to prevent leakage.

In Northern Wyoming a glycerin storage tank has been connected to a farms irrigation system. Before crops emerge, a valve is opened to water down the glycerin and spread it onto the fields.

A third option is to feed the crude glycerin to ruminants. In actuality, there are no regulations that affect the use of glycerol as a feed additive. The overall consensus is that crude glycerol can comprise up to 15 percent of a ruminant animals diet and 15 percent of pelleted feed mix. Dairy cows are the exception where a study found the limit to be 1 to 5% with an improvement in energy balance when glycerol comprised 2% of their diet.

Assuming the crude glycerin is 80% pure glycerin, Brett Hess from the University of Wyoming thinks that crude glycerol should sell at 89% of the price of cornstarch. This would give it a price of 1 to 2 cents per pound or 10 times current market value. However in most cases, crude glycerin is 50 to 60% pure and thus should be discounted 33%.

The two other product options for glycerin, making hydrogen or propylene glycol, are still in the research phases. Since the process is complicated, when and if it becomes technologically mature, it will likely be done in centralized plants. This basically means small biodiesel producers will probably only need to invest in storage and sell their glycerin much like a lot of restaurants are selling their waste oil.

The other upcoming use for glycerin is propylene glycol. It can be used as a non-toxic anti-freeze, coolant, or deicer. Although petroleum based ethylene glycol is currently much cheaper, it remains a non-renewable resource that is highly toxic and as such is bound to lose popularity.

Propylene glycol is created by reacting glycerin with copper chromate, which sells for roughly fifty cents/gram. Full costs are currently unknown since this process is being perfected, which imperative given the current 47% efficiency in conversion.

Raphael Shay has worked on biodiesel in Canada, Denmark and the United-States. He is now the Outreach Coordinator at iCAST, where he bridges iCAST's projects with the people who need them most. iCAST is a Colorado based organization that facilitates renewable energy and energy efficiency projects that lead to community development.This article is based in part from Ryan Brown's report "Biodiesel Co-Product Markets in Wyoming (PDF)" as well as Bret Hess' report "Value of Crude Glycerin for Ruminant Livestock (PDF)." Both are available on the iCAST's biodiesel project page.