FOSSIL FUEL–FREE FLYING: The C-17 transport plane pictured here over Manhattan flew from McChord Air Force Base in Washington State to McGuire Air Force Base in New Jersey on a blend of synthetic fuel derived from natural gas and regular jet fuel, the first transcontinental synthetically fueled flight. View slideshow here
COURTESY OF U.S. AIR FORCE

In December the U.S. Air Force flew a C-17 transport plane across the country powered in part by a new propellant: natural gas transmuted into a synthetic liquid fuel. Heat and catalysts converted methane into syngas (carbon monoxide and hydrogen) which were then transformed into liquid hydrocarbons (otherwise known as oil and its derivatives): petroleum, gasoline and, in the case of aviation, kerosene.

"Hitler flew Messerschmitts on it," says William Anderson, assistant secretary of the U.S. Air Force for installations, environment and logistics, about such Fischer-Tropsch synthetic fuel, which can be made from methane, coal, plant oils—even wood waste. "We believe that having a secure domestic source of fuel makes it easier for us to do that mission [to fly and fight]. It is less likely that there would be some disruption to the fuel source that we need to fly airplanes."

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Whether for supersonic fighter jets or commercial airliners, the aviation world has begun a quest for the fuel of the future, transitioning away from petroleum-derived JP-8 and Jet A varieties to Fischer-Tropsch synthetics or biofuels. Driven by security and environmental concerns as well as skyrocketing oil prices—United Airlines more than doubled its fuel surcharge per ticket to $50 on January 12—the aviation industry continues to cut back on fuel burn as it searches for cleaner, cheaper alternatives.

"We are definitely interested in having an alternative source of energy available to us for both economic and environmental reasons, not to mention pure supply," says John Heimlich, chief economist at the Air Transport Association of America (ATA) in Washington, D.C., which represents airlines responsible for more than 90 percent of U.S. passenger and freight air traffic. "There are a host of fuels out there; some could be better, some could be worse. We need to find something at least as good, if not better."

Rock to Liquid
Jet aircraft today typically burn kerosene, an energy-dense hydrocarbon fuel that delivers as much as 48 megajoules per kilogram (20,700 British thermal units per pound), allowing for long-distance travel. Americans have taken advantage of this capacity, according to the U.S. Bureau of Transportation Statistics: Airlines reported ferrying more than 72 million passengers last July, a record high for a single month.

At the same time, the aviation industry has become far more fuel efficient in the face of soaring prices. (Airlines spent $37 billion for fuel alone in 2007 through November and may follow United in imposing steeper fuel surcharges on customers in 2008.) According to the ATA, the industry has reduced the amount of fuel burned by 23 percent since 2000 by taking such steps as making aircraft lighter and introducing more efficient engines. "Today, Northwest Airlines is averaging roughly 50 passenger miles per gallon [21 kilometers per liter] of fuel," says Tim McGraw, Northwest's director of safety, health and environment, largely by replacing its aging fleet of airplanes with newer, more efficient jets.

The primary reason for such improvements has been the steady rise in fuel costs. For example, the Air Force has watched its energy spending double since 2003 even though it cut fuel consumption by more than 10,000 barrels a day during the same period. "Over 80 percent of the entire Air Force energy buy is in liquid aviation fuel," Anderson says. "That represents a little less than $6 billion a year of taxpayer money that goes into feeding our fleet with fuel."