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Research Lab leads way to test, certify synthetic fuels

  • Published
  • By Laura L. Lundin
  • Air Force Research Laboratory Public Affairs
As an integral partner in the Office of the Secretary of Defense Assured Fuels Initiative, the Air Force Research Laboratory is leading the investigation for suitable, domestically produced alternative fuels for military use.

AFRL is now certifying suitable fuels for the Air Force fleet, as part of the Air Force's comprehensive energy strategy.

Efforts stem in part from successful flight tests in September wherein two of a B-52's engines ran on a synthetic fuel, made from a 50-50 blend of traditional crude-oil based fuel and a Fischer-Tropsch fuel derived from natural gas, while the remaining six engines ran on traditional JP-8 fuel. The tests occurred at Edwards AFB, Calif.

According to William Harrison, senior advisor for the OSD Assured Fuels Initiative and an engineer with AFRL's Propulsion Directorate, "AFRL's involvement has been to look at the science and technology behind the FT fuels, focusing on the fundamental lab work and basic fuel properties while exploring the suitability and feasibility of using them to meet Air Force needs. Now that the two-engine flight tests are complete, we will focus on the certification of the fuel for all Air Force aircraft and ground-support and look at how the fuel will work with the Air Force's existing logistic infrastructure."

Mr. Harrison added that developing an organized, streamlined certification process for the FT fuel is a collaborative effort involving a team from AFRL, the Air Force Materiel Command Engineering Office, and the Aeronautical Systems Center.

The Air Force is also looking for full interchangeability in the marketplace, and, Mr. Harrison said the certification will be on the 50/50 blend.

"However, we will keep researching the possibility of increasing the blend ratio as well, and with the successful flight tests and the preliminary data, we know that we have a proven range that works," said Mr. Harrison.

"With the 50/50 blend, we took a very conservative and methodical approach to the research, allowing ourselves the best options," Mr. Harrison continued. "The 50/50 blend is the closest to the JP-8 fuel that is currently used,"

In addition to the fuel certification, AFRL is continuing to research the suitability of using FT fuels in other military aircraft applications such as hypersonics and unmanned aerial vehicles.

Through these efforts, the Air Force has taken an innovative approach to find domestically-produced alternative fuels that will lead to greater fuel efficiency and help alleviate dependence on foreign energy sources.

In an official letter to Airmen in September, Secretary of the Air Force Michael W. Wynne stated that energy independence is a key element to ensuring the United States' economic and national security, and an assured domestic supply of fuel and an aggressive energy conservation plan will benefit the entire Air Force.

Along with the assured domestic supply, FT fuels are also very clean, reducing emissions and particulates in the air. Mr. Harrison points out that one major advantage to the FT process is that it removes the aromatic compounds and sulfur from the fuel. "It is a very clean fuel that will lead to a reduction in aircraft emissions," said Mr. Harrison. "During the research with the T63 turbine engine testing, we found that even low amounts of the FT fuel, when blended with JP-8, significantly reduced exhaust emission particulates."

Research has shown that FT fuels have excellent low temperature properties, which can help improve capacity for flying at higher altitudes, and have increased fuel thermal stability, which allows development of more fuel efficient propulsion systems.

"We are looking at coal as the most attractive option at this point because it is viable both technically and economically, with vast resources available domestically," said Mr. Harrison. "An added benefit is that the plants that produce the synthetic fuel can also produce electricity as a by product of the process at the same time, which is a very beneficial commonality."

Plans for a B-52 flight demo using synthetic fuel in all eight engines are under way and could occur in 2006.