Richard Branson and Boeing heap hope-and hype-on biofuels.
- By Michael Milstein
- Air & Space magazine, September 2007
University of Wisconsin
(Page 2 of 5)
Although an unmanned jet powered by a hydrogen fuel cell flew over Switzerland this year, today’s fuel cells—which generate electricity by combining the charged particles of hydrogen and oxygen—lack the power to run anything more than a small aircraft.
But Boeing has hopes of replacing the auxiliary power unit generators with more efficient fuel cells that produce little or no pollution, even when running on jet fuel, in order to power the electrical systems on commercial airplanes.
There is one existing alternative jet fuel, made from coal or natural gas through what’s known as the Fischer-Tropsch Process. It was pioneered in Germany during World War II when oil was in short supply and later in South Africa when that nation was ostracized by oil-producing countries for practicing apartheid.
Fischer-Tropsch fuel burns cleaner than traditional jet fuel, spitting out up to 90 percent less of the particulate pollution that muddies the air and causes health problems. The fuel also leaves engine parts clean and shiny instead of blackened with soot. And it soaks up more heat, freeing airplanes from the requirement of weighty vents to get rid of the heat as they fly.
The trouble with Fischer-Tropsch, environmentally, is that the process of making it—turning coal to gas, then gas to liquid—releases nearly twice as much greenhouse gas as regular jet fuel does over its life cycle. Researchers are trying to figure out how to sequester excess carbon dioxide gas, possibly by capturing it and storing it underground.
In December 2006, the Air Force, which guzzled nearly $6 billion worth of jet fuel last year and wants to convert half its fleet to synthetic fuel (based on natural gas or coal) by 2016, used a B-52 to test Fischer-Tropsch fuel made from natural gas.
But to be of any use, Fischer-Tropsch fuel production must be scaled up dramatically, says Richard Altman, executive director of the Commercial Aviation Alternative Fuel Initiative, an alliance of airplane manufacturers, airports, and airlines formed last year.
Altman spent nearly 40 years as an engineer at Pratt & Whitney and recalls a small band of chemists who quietly toiled for years over fuel blends, hitting up division heads for funding. Now, suddenly, they’re in the spotlight.