NASA's Alternative-Fuel Aircraft Projects: Green Technology Articles: Eco20/20

NASA's Alternative-Fuel Aircraft Projects

First in 2009, and then again in 2011, NASA conducted Alternative Aviation Fuels Experiments. In the first experiment, the fuels were made of coal and natural gas. In the 2011 tests, the fuel was made of animal fat, an abundant byproduct of the meat industry. Disparage that as fully as you desire, no defense of the meat industry will be made here. Nevertheless, animal byproducts do exist, so the decision to test them as a fuel produced from a renewable resource was considered a valid recycling option.

A sincere hope must be cherished that the next test will be made with plant or algae based bio-oils. Meanwhile, these tests were deemed a success.

AAFEX (2009)

In January and February of 2009, NASA's first AAFEX was established to investigate the effects of synthetic fuels on engine performance, along with gas and particle emissions testing, and measurement of volatile aerosol formation in exhaust plumes.

* Together with an assortment of research teams formed by five companies, three universities, and a few other US government agencies, NASA tested two non-petroleum jet fuels at the Dryden Flight Research Center in California. The test vehicle was a DC-8. It stayed on the ground for the tests. The synthetic fuels were tested unblended and in 50-50 blends of synthetics with regular jet fuel. One of the fuels was derived from coal; the other was made from natural gas. Both were created using the Fischer-Tropsch process, a chemical reaction in which liquid hydrocarbons are distilled from a gaseous mixture of carbon monoxide and hydrogen.

o To help isolate fuel related variations from those caused by other factors, such as ambient temperature, samples were alternately drawn from the exhaust of a left-wing engine that always burned standard JP-8, and a right-wing engine that burned one of the test fuels.

* Results indicated that burning synthetic fuels substantially reduced particle emissions from aircraft engines.

AAFEXII (2011)

NASA hosted its second alternative fuel test in March of 2011. This time, the fuel was processed from waste chicken and beef tallow.

* The testers again ran one engine using Jet Propellant 8. The fat-based fuel, which was called hydro-treated renewable jet fuel, was tested in another engine, and a 50-50 blend of the two fuels was also tested. The researchers again measured the fuel's performance; they checked the exhaust for chemicals and particulates; and this time they also checked for nitrogen oxides, which contribute to smog.

* The 2011 test results again showed that biofuels are cleaner-burning, and release fewer pollutants into the air. Black carbon emissions showed a 90 percent reduction at idle and exceeded 50 percent reduction under a simulation of take-off thrust. The animal-fat biofuel also produced lower sulfate and hazardous emissions than the JP8 fuel.

It is unfortunate that the search for alternative fuels isn't driven wholly by environmental concerns. This would have been a happier report, if these petroleum-free fuels had been greener.