AFRL Examines Renewable Fuel Sources

  • Published
  • By Tom Brown
  • Propulsion
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  Illustrating Air Force Research Laboratory's position at the cutting edge of alternative fuels exploration, an A-10C Thunderbolt II underwent recent flight demonstration powered on a blend of standard JP-8 fuel and hydrotreated renew-able jet, or HRJ, biofuel. The groundbreaking event marks one successful step in a more comprehensive Air Force undertaking to certify an entire family of biomass fuels. While the bio-based component used for the A-10-tested fuel blend is a camelina plant derivative, this particular substance is not the only option for producing HRJ fuel. On the contrary, wide varieties of plant oils (e.g., algae) and animal fats (e.g., chicken) are candidates in this capacity.

As the Department of Defense's largest consumer of jet fuel, the AF uses 2.4 billion gallons per year, about the annual fuel equivalent of a midsized commercial airline. Accordingly, the service--intent on switching half of the continental US jet fuel requirement to alternative fuels by 2016--maintains an ongoing partnership with the Commercial Aviation Alternative Fuel Initiative to develop biofuels. As part of this collaborative endeavor, AFRL has examined a broad range of feedstock sources for their respective fuel production viability and ultimate cost-competitiveness with petroleum fuels. While propulsion engineers are continuing exploration along these lines, they have already completed a substantial amount of work towards realizing HRJ fuels and are turning their collective attention to the potential discoveries that lie ahead, such as fuels made from forest or agricultural waste and similarly eco-friendly and cost-effective capabilities.

Following another demonstration flight (this one involving an F-15) and static engine tests--to be performed at Arnold Air Force Base, Tennessee--the plan is to conduct full-blown certification test efforts with two Pathfinder programs: one with a C-17 representing the mobility fleet (in a test tentatively scheduled for late summer at Edwards AFB, California), and the other with an F-22 Raptor representing the entire fighter fleet (slated for late fall). Still under consideration is a third such program, which would likely employ the Global Hawk platform to evaluate the fuel in the extreme environment of "worst case" temperature and altitude. The intent is to be able to leverage a 50/50 blend of JP-8 and HRJ fuels without modifying existing system or fuel infrastructure. The certification program will apply to other platforms that burn JP-8 in wartime as well, such as remotely piloted vehicles, Humvees, and even power generators.

Notably, the breakthrough research of alternative fuels represents only a portion of the AF's plan to reduce oil dependency. AFRL is also working to reduce demand by developing advanced engines and other emergent technologies. Nonetheless, as the DoD, the aviation community, and the nation look to a shared future of independence from nonrenewable energy sources, the AF's historic strides in alternative fuels will yield positive economic and environmental outcomes of benefit to military and commercial interests alike.