Using Plants Instead of Petroleum to Make Jet Fuel

Oct. 3, 2008 - David Biello - ScientificAmerican (SciAm.com)

New aviation biofuel made from soybeans and other crops proves identical to oil-based kerosene

JET BIOFUEL: Scientists in North Dakota have turned oil from plants like soybeans into jet fuel that is equivalent to kerosene derived from oil. ©George Clerk/istockphoto.com

Chemical engineers in North Dakota have successfully turned oil from plants—canola (rapeseed), coconuts and soybeans—into jet fuel indistinguishable from the conventional kind, according to U.S. government tests. Working with the U.S. Department of Defense's Defense Advanced Research Projects Agency (DARPA), scientists at the Energy & Environmental Research Center (EERC) at the University of North Dakota turned these plant oils into fuel that had a similar density, energy content and even freezing point.

"It's got a freeze point of –47 degrees Celsius (–52.6 degrees Fahrenheit). Anyone familiar with biodiesel can tell you that's no small feat," says chemical engineer Chad Wocken, EERC environmental technologies research manager. "It's processed so that it contains only the same hydrocarbon molecules present in petroleum fuel."

Although he declined to explain the exact details of the process, Wocken says it is thermocatalytic—in other words, the engineers heat the plant oils in the presence of an undisclosed catalyst to create a slew of petroleum products. In fact, the process is not unlike conventional oil refining in that it produces everything from the kerosene used as aviation fuel to regular gasoline. "The processing costs would be similar and comparable to petroleum oil refining," and perhaps even less expensive, Wocken notes, "because you're not dealing with contaminants like sulfur."

Of course, the biofuel's ultimate price tag is yet to be determined as only "gallons" of it have been brewed compared with the more than 60 million gallons (225 million liters) of jet fuel consumed daily in the U.S. But it will in large part depend on the price to grow the crops themselves—all have been fluctuating in recent months due to newly volatile global commodity markets.

Virgin Atlantic has flown a jumbo jet on a combination of conventional jet fuel and biofuel made from palm oil, and a jet powered solely by biodiesel has stayed aloft for more than 30 minutes—albeit with a special device to keep its fuel from freezing at high altitude. And the EERC fuel is not the only bio-based jet fuel available: UOP, LLC, a division of Honeywell Specialty Materials, has a similar fuel made from vegetable and animal oils, whereas algae-grower Solazyme, Inc., has derived a jet fuel from pond scum that meets ASTM (American Society for Testing and Materials International) standards.

"We did this outside the DARPA program," says Solazyme CEO Jonathan Wolfson. "As green as people want to be, they don't want to pay more for fuel."

The EERC is currently in the process of producing 25 gallons (95 liters) of the bio–jet fuel for ground testing in a jet engine as early as next month. "The thing that needs to happen is a purchase order to come through from the Air Force so we can get [the] investment to build that first plant," Wocken says. "We could get a plant operational in two to five years if there were a commitment to buy the fuel."