Increasing oil prices are prompting government and industry researchers to accelerate their investigations into powering jet engines with alternative fuels. These scientists are seeking solutions to problems such as the high cost of operating a jet on alternative fuel and producing and carrying the large quantity of fuel that would be needed on board the plane when in flight.

Despite the obstacles, research on alternative fuel-powered jet engines continues. Biodiesel is one example of an alternative fuel being explored. However, because aircraft reach high elevations while in flight and because biodiesel freezes at a higher temperature than traditional fuel, many feel that it is not a viable option at this time.

Several alternative fuel options for aircraft are being researched.

Several alternative fuel options for aircraft are being researched. Credit: Ted Whiteside, Boeing

Synthetic fuels made by turning coal, oil shale, or natural gas into a liquid are another alternative fuel possibility for jet engines. This could prove to be a less-expensive method since the United States has large natural gas and coal reserves. In September 2006, the U.S. Air Force plans to send a B-52 bomber on a test flight with two of its eight engines operating on Fischer-Tropsch fuel, which is derived from natural gas and named after the two German researchers who engineered it.

Airplanes could also someday fly on hydrogen fuel. Gerald Brown, a senior research engineer with NASA Glenn Research Center, said relatively little modification would be needed to run a jet engine on liquid hydrogen. However, liquid hydrogen must be stored at -424˚F, and airplanes would have to be redesigned to carry it on board because hydrogen takes up more space than regular jet fuel. Another issue, according to engineer Stan Seto, is that the amount of water released when hydrogen burns in the jet could turn it into a cloud-making machine. The cost of hydrogen fuel is another concern.

According to researchers, alternative fuel options for aircraft will continue to be explored, despite the obstacles encountered thus far, because the environmental and long-term cost benefits make their investigation worthwhile.

“It’s just so much easier to develop a fuel for automobile applications than for airplane applications,” said Billy Glover, The Boeing Company’s director of environmental performance.

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