Will greener planes fly?

News and commentary about environmental issues.
July 22 2008 2:24 PM

Will Greener Planes Fly?

Fuel-strapped airlines need a new approach, but technological fixes are hard to find.

A model of the Bombardier C-Series aircraft. Click image to expand.
A model of the Bombardier C-Series aircraft

Last week, Continental, Delta, and American, three of the country's largest airlines, announced combined second-quarter losses of nearly $2.5 billion, the worst downturn to hit the industry since right after 9/11. Unlike previous rough patches, the airlines' current slump won't necessarily end once the economy recovers. That's because the culprit isn't just sagging demand; fuel prices, now the single largest expense for U.S. airlines, have doubled since last year.

That grim fact—plus the constant wrath of the climate-change movement—gives airlines a massive incentive to find a more fuel-efficient way to fly. But how fast can the industry change?

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In the short run, airlines will try to make up some of that shortfall by raising fees and slashing service. But over the longer haul, they need to start looking at two kinds of changes: a different kind of plane and a different kind of fuel.

Some movement toward greener airplanes is already on the way: At last week's Farnborough Air Show outside London, Bombardier unveiled its C-Series jet, which the company claims uses 20 percent less fuel than other jets. That efficiency puts the C-Series in the same category as Boeing's new 787 Dreamliner, which the company hopes to have in the air by the end of next year.

But even if airlines could magically replace their entire fleets with these new planes tomorrow, they'd still be in trouble. Delta's year-on-year fuel costs went up by 50 percent in the second quarter to nearly $1.7 billion; American Airlines' second-quarter fuel costs went up 47 percent to $2.4 billion. A 20-percent cut in fuel costs would still leave both companies in the red.

There are other potential answers. In 2003, Cambridge and MIT began designing a new type of plane, one so quiet that it would be inaudible beyond the airport fence—and it uses less fuel, to boot. The project, called the Silent Aircraft Initiative, produced a concept aircraft called the SAX-40, a sleek new plane that would get an estimated 125 passenger-miles per gallon of fuel *, more than the Dreamliner (about 100 passenger-miles per gallon) and much more than current passenger jets (less than 80 passenger-miles per gallon). According to the project's Web site, the SAX-40 would get the same mileage per person as a Toyota Prius Hybrid carrying two people.

What makes the SAX-40 design superior to more traditional jets? Like the Dreamliner and the C-Series, the Cambridge/MIT design uses lighter-weight materials and more fuel-efficient engines. But what sets the aircraft apart is its frame.

Like traditional airplanes, Bombardier's C-Series is still "a tube with wings on it," said James Hileman, a researcher at MIT and one of the project's chief engineers. Hileman and his team took that basic tenet of aircraft design and tore it up. "Instead of having the fuselage for people and the wings generate lift," he asked, "why don't you have the fuselage also generate lift, and blend it out into the wings?" The result was a plane that was both quieter and significantly more fuel-efficient—similar in appearance to the B-2 stealth bomber.

But Hileman doesn't expect a commercial aircraft like the SAX-40 to enter production anytime soon. First, it costs more to build than the standard tube-with-wings design, at least for now. Second, building a new kind of plane would force aircraft manufacturers to take on more risk. Boeing's Dreamliner has already been delayed repeatedly because of technical glitches and problems with suppliers—a risk that would only increase with a fundamentally new design.

A more promising route to cutting fuel costs, at least in the next few years, comes from changing the kind of fuel aircrafts use. Can planes fly on jet fuel made from something that's cheaper than oil and that leads to lower greenhouse-gas emissions?