B100 to the Arctic Circle

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It's almost unbelievable, but the promoters of the Indiana-based Permaflo biodiesel process had an independent lab test their biodiesel's cloud point at minus 45 degrees Fahrenheit before they shipped 250 gallons of it to Alaska. It was the ultimate road test � driving diesel vehicles on B100 in Alaska's late winter conditions.

The seven Indianans flew to Fairbanks where they were met by three researchers from the University of Alaska�Fairbanks, who drove the group in a diesel-powered UAF minibus from Anchorage to Fairbanks amid a late-winter March storm. Two diesel pickups carried part of the crew 250 miles north to the Arctic Circle, where they camped overnight at minus 24 degrees F temperatures.

"We're extremely happy with the results of the test," says John Whittington, vice president of Integrity Biofuels Inc., the 5 MMgy plant at Morristown, Ind., where the fuel was processed. "We knew it was good � we knew from tests. But it really [had] a different feeling when you're out there in a vehicle in those extreme temperatures and actually see it perform."

Doug Morrow, a soybean farmer and president of the Indiana Soybean Alliance, was equally pleased. "It's quite amazing. When we were in Alaska, we weren't even concerned about the fuel � but we were concerned about ourselves staying warm."

Simple, Solid Science
Purdue University researcher Bernard Tao laughs when asked whether people react to his biodiesel refining process by saying it sounds too good to be true. "Yes, we hear that, but we proved we can make it," he says. Tao's goal has been to accomplish for biodiesel what the petroleum industry has done with oil refining � take any crude oil regardless of its source or quality and produce a fuel with consistent properties.

In petroleum refining, the differing boiling points of the molecules allow the fractions of crude oil to be separated as the mixture's temperatures rise in the distillation process. In biodiesel, all the molecules have about the same molecular weight, Tao points out, so distillation is not an efficient means of separating its fractions. However, biodiesel molecules do have chemical differences, commonly known as saturated and unsaturated fats, caused by the absence or presence of double carbon bonds. Saturated fats with no double carbon-carbon bonds are straight, linear molecules, whereas the double-carbon bond in unsaturated fats puts a kink in the molecule.

Tao adds urea � the common, granular agricultural fertilizer � to finished biodiesel in order to set up the physical separation known as cathration or host-guest complex. Not soluble in biodiesel, the urea molecules associate with each other to create a lattice of hexagonal tubes at the molecular level. The linear saturated fat molecules can slip into those tubes where they are held in a weak composite, becoming a semi-solid that precipitates to the bottom. "You can think of it as putting your arm down a pipe," Tao says. "As long as you have your arm straight you can fit it in, but if you bend at the elbow you can't fit it in." The kinked, unsaturated molecules rise to the top, effectively separating the biodiesel into a cold-flow fraction on the top and a warm-flow fraction on the bottom. The separation occurs at room temperature.

The difference in properties between the separated B100s is remarkable. The saturated fats in the warm-flow fraction have high melting points of 35 to 40 degrees Celsius, or approximately 155 to 120 degrees F, says Tao. Introducing one double bond for a saturated fat drops the melting point to minus 15 degrees C, and when another double bond is introduced to make it polyunsaturated it drops another 15 degrees C. His experiments have shown that biodiesel's cloud point can be adjusted to a desired level regardless of the feedstock used, by varying the concentration of urea. "On this process, everything works out," Tao says. "The urea is recyclable � there are no energy inputs and no waste products." One downside of the cold flow fraction is with the saturated molecules that contribute to oxidative stability having been removed, the remaining biodiesel requires additives to retard oxidation.

Urea is the only ingredient for the cathration process, Tao says, and recovering the urea is as simple as the process. Although urea is not soluble in biodiesel, it is soluble in water and can be separated from the gelled warm-flow fraction through water washing. The biodiesel floats to the top, and the water and urea drop to the bottom. In waterless processes, Tao adds, the urea and warm flow biodiesel mixture can be heated up to 110 degrees C. "Urea nicely melts and is much denser than biodiesel," he says. "The biodiesel floats to the top. Let the urea settle to the bottom, solidify and then recycle to the front of the process again."

"Spreadable" Biodiesel
The applications for the cold-flow fraction are obvious, and were well demonstrated on the promoters' Alaskan trip (see sidebar). Being the consistency of spreadable margarine at room temperature, the warm fraction presents some different issues. There are some intriguing possibilities beyond using it in summer biodiesel blends, Tao says. One possible use may be as a paint remover, since the gelled biodiesel would cling to vertical surfaces and works well for stripping paint. Tao's civil engineering colleagues at Purdue have worked out another application � using the warm-flow biodiesel as the base for a concrete sealer. The material seals concrete to a high depth, protecting it from salt and water damage from freeze-thaw cycles; plus, it automatically seals cracks that appear from physical stresses. "It makes concrete much more durable over the long term in winter conditions," Tao explains. "It could be a tremendous opportunity for biodiesel; but its uses can go far beyond transportation, with the potential for a larger volumetric usage than the fuel business." Increasing the life span of bridges and highways would have a tremendous impact, he adds, but the initial reaction from concrete manufacturers and highway departments was skeptical. "It's like cold-flow biodiesel � they say if you can really do this, it is great," Tao says chuckling. "We've done the testing here," he adds, pointing out that Purdue has a national concrete testing laboratory. "The [concrete] industry is starting to get interested."

Commercialization Ahead
With the science established and the favorable results from the Alaska demonstration, the Permaflo project is ready for the next step. Indiana's Soybean Alliance has supported the research and development with grants over five years totaling nearly $1 million, says Ryan West, ISA director of technology commercialization. Engineering studies are needed next to establish production costs and necessary adaptations for various configurations. The process can be done with minimal modifications, as was done at Integrity Biofuels where minor changes to piping were made in the batch process. Integrity has manufactured approximately 4,000 gallons to date, however, Tao says that more modifications may be necessary for efficient production in either batch or continuous flow processes. Tao anticipates the capital requirements will be reasonable.

ISA is in the process of evaluating how to proceed, according to West. "We're a little slow to turn it over to anybody," he says. "Not because we're afraid it gets out there, but exactly the opposite. We're afraid it may become very restricted, and we're not interested in that."

Susanne Retka Schill is assistant editor of Biodiesel Magazine. Reach her at [email protected] or (701) 738-4922.