The Air Force looks for economy at the pump.
- By Mike Harbour
- Air & Space magazine, September 2006
The Air Force uses half the U.S. Government’s fuel supply every year. Half. In other words, it takes all the tanks in Iraq, all the ships in Norfolk, and all the federal fleet cars driven by bureaucrats on per diem to match the USAF for sheer gas guzzling.
And with a jet fuel bill topping $4.7 billion last year, the Pentagon is looking for alternatives.
DARPA, the defense department’s research agency, is USAF Scientific Advisory Board and the Nazi Germany for an answer.
The same chemical method used to create gasoline for the Axis war machine during World War II may help power the U.S. military in 2008, thanks to a Department of Defense initiative to find a synthetic alternative to petroleum-based fuel. An Air Force B-52 made a flight over California in September with two of its eight engines powered by synthetic kerosene based on a process known as Fischer-Tropsch developed at the Kaiser Wilhelm Institute in the 1920s. “We demonstrated that we could burn Fischer-Tropsch fuel in that aircraft,” says William Harrison III, fuels branch chief of the Air Force Research Laboratory’s Propulsion Directorate. “The engines performed as we expected, just like they would with the JP-8 fuel.”
But unlike JP-8, the equivalent to commercial Jet-A fuel, Fischer-Tropsch fuel can be created from coal, natural gas, or biological matter. All three sources are plentiful in the United States, one reason why the process moved from “off the stove,” Harrison says, to number one on the list of Pentagon alternative fuels efforts. After the basic source, or feedstock, has been turned into an intermediate synthesis gas (syngas), it is then refined into fuel.
“That’s what’s nice about Fischer-Tropsch: you can use any hydrocarbon feedstock to make the syngas, and then, once you have the clean syngas, the fuel is all very much the same,” Harrison says.
The initial test flight, made from Edwards Air Force Base in California on September 19, was the first time an Air Force jet flew with synthetic fuel blended with 50 percent JP-8 in its tanks. Ronald Sega, Under Secretary of the Air Force, as well as a former pilot and astronaut, served as a crewmember on the two-hour flight. Although cut short by a non-related mechanical problem, the test was determined a success, and a second flight the following week confirmed the engines operated normally using the blend.
By next year, the test aircraft, a B-52H from the 5th Bomb Wing at Minot Air Force Base in North Dakota, will be flown with all eight of its Pratt & Whitney TF33 turbofan engines burning the synthetic blend. Then it will fly again in cold weather. Once those tests are complete, certification for use throughout the bomber fleet won’t be far off, followed by tests on fighter aircraft.
“Right now, we have an Air Force team working out the strategy for the testing beyond the B-52,” Harrison says. “We’re collaborating with the engine companies that produce the engines for us [and] we will be doing some level of testing both in 2007 and 2008.”
Another benefit of Fischer-Tropsch fuel is lower emissions. Compared to petroleum-based fuel, tests show the synthetic one produces less carbon dioxide, fewer particulates, and no sulfur. That, combined with its lower price, makes the Air Force eager to start filling tankers with the stuff as soon as possible.
Mike Harbour is a freelance writer in Helena, Montana who specializes in transportation subjects.