When Will Planes Go Green? While the automotive industry is intensely promoting hybrid and ethanol-based engines, the aviation industry is yet to make more than a peep about alternative fuels. Dr. Robert Hendricks of NASA's Glenn Research Center speaks with Andrea Seabrook about whether we'll ever be "flying green."

When Will Planes Go Green?

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One topic sure to come up is climate change.

It's on people's minds right now. Take this car commercial.

(Soundbite of TV ad)

Unidentified Woman #1: I want to change the way I drive.

Unidentified Man #1: I want a vehicle with zero emissions.

Unidentified Man #2: I want a hybrid that fits my life.

SEABROOK: With oil prices through the roof, automakers are capitalizing on Americans' craving for cars that run on alternative fuels. But another big polluter when it comes to greenhouse gasses is aviation: Airplanes, will they ever start flying green?

Dr. ROBERT HENDRICKS (Senior Technologist, National Aeronautics and Space Administration Glenn Research Center, Cleveland): I think, perhaps, we're leading the automakers in that respect.

SEABROOK: That's Robert Hendricks. He's a senior technologist at NASA's Glenn Research Center in Cleveland, and he's been studying the use of alternative fuels for aviation. He says there's a reason aircraft companies haven't gone to market with alternative fuel engines.

Dr. HENDRICKS: It's okay if you have some fuel problems with your mobile, perhaps, because you can pull over, culture play or something like that. But when you're up there and flying around, that's not a good thing to have your engine stop.

SEABROOK: Hendricks points out that researchers have two challenges to make fuel cheaper and greener. Achieving both is going to be a long-term goal.

Dr. HENDRICKS: We have a lot of airplanes that's hanging around for a long time. They're called Legacy Aircraft. And they may be in - even 30 years old and you have to fly those types of airplanes…

SEABROOK: Which run on traditional jet fuel. There's no retrofitting those planes. In the long-term, Dr. Hendricks expects builders will offer aircraft with low or zero carbon emissions. And get this, it may sound scary but liquid hydrogen could be the answer, eventually.

Dr. HENDRICKS: That's out maybe 40, 50 years or something like that. You have to be very careful with hydrogen. Hydrogen is a forgiving fuel but at the same time, it's not forgiving if you don't handle it properly. So you need to be very cautious and very pragmatic about the safety features of the hydrogen in the use of aircraft.

SEABROOK: But since the Legacy Aircraft can't be outfitted for hydrogen power, Dr. Hendricks has been looking at several near-term solutions. What may work, believe it or not, is algae. Hendricks has been looking into extracting oil from plants called halophytes, which are saltwater-tolerant. That could satisfy those concerned about over-farming crops like corn and soybeans.

Dr. HENDRICKS: If we use these types of plants, we do not use arable land. We use arid land.

SEABROOK: Okay, so you can use land that's bad for agriculture?

Dr. HENDRICKS: Yes, and most of the population live within about 50 kilometers off the seacoast and that's the exactly where halophytes would prosper very well.

SEABROOK: Hendricks says some 85 billion gallons of bio jet fuel could be produced from halophytes grown on a landmass equivalent to the size of Maryland. That's a lot of green flying. But until we see algae agribusiness, airlines are looking for another solution. Jet fuel additives, something derived from coal or natural gas which are plentiful here in the United States.

What environmental good does using coal do over using oil?

Dr. HENDRICKS: Well, that's a very good question and I hate to tell you the very good answer namely it is double CO2 and that's not good for the climate and…

SEABROOK: It's doubles the CO2. In fact, it's worse.

Dr. HENDRICKS: Yes, it's much worse. Yeah.

SEABROOK: So what problem does it solve?

Dr. HENDRICKS: Well, it gets us away from the teak oil problem, namely that you're running out of oil and the price of oil itself is very high - that's petroleum-base oil that I'm talking about.

SEABROOK: So, it's easier to use coal responsibly than it is to use oil responsibly?

Dr. HENDRICKS: That's a hard question and I don't know quite how to answer that. I think that if we use our fuels responsibly, we wouldn't be in a predicament we're in right now.

SEABROOK: Robert Hendricks continues to look for alternative aviation fuels at NASA's Glenn Research Center.

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