May/June 2011

NASA turns animal fat into jet fuel

NASA recently performed emissions testing on alternative, renewable fuels for a greener and less petroleum-dependent future. The search for alternative fuels is driven by environmental concerns as well as a desire for reduced reliance on foreign sources.

"Renewable" means that the fuel source isn't some form of fossil fuel. Recently, a team at NASA's Dryden Flight Research Center in California tested renewable biofuel made from chicken and beef tallow in one of the four engines of a DC-8 airplane.

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The airplane remained on the ground during the test, known as the Alternative Aviation Fuels Experiment, or AAFEX, while aeronautics researchers measured the fuel's performance in the engines and examined the engine exhaust for chemicals and contamination that could contribute to air pollution. It was the first test ever to measure biofuel emissions for nitrogen oxides, commonly known as NOx, and tiny particles of soot or unburned hydrocarbon. NOx contributes to smog and particulate matter contributes to respiratory and cardiovascular ailments.

"The test results seem to support the idea that biofuels for jet engines are indeed cleaner-burning, and release fewer pollutants into the air. That benefits us all," said Ruben Del Rosario of NASA's Glenn Research Center in Ohio.

The team ran one engine using Hydrotreated Renewable Jet Fuel, or HRJ, and another engine using Jet Propellant 8, or JP-8, fuel, which is very similar to the industry standard Jet-A fuel used in commercial aircraft. They also ran one engine using a 50-50 blend of the two fuels.

The experiment's chief scientist, Bruce Anderson of NASA's Langley Research Center in Virginia, said in the engine that burned the biofuel, black carbon emissions were 90% less at idle and almost 60% less at takeoff thrust. Anderson added the biofuel also produced much lower sulfate, organic aerosol, and hazardous emissions than the standard jet fuel. Researchers will spend the next several months comparing the results and drawing conclusions.