Flying on Vegetables

The scheduled flight on Wednesday of a Continental Airlines 737 fueled in part by biofuels made from jatropha and algae was experimental (see my report on the state of biofuels in the airline industry from Wednesday’s paper here). But if the fuel can be certified by international standards agencies, it could become as common as, say, ethanol added to gasoline.

It might be even more so, because the goal is a “drop-in” substitute that can be used at any percentage, in any jet or any airport fueling system.

In theory, people in the industry say, replacing petroleum in airplanes could be easier than replacing it in cars, even though jet fuel has to meet specifications that are of little concern on the highway, like weight (hauling fuel is a major use of fuel, after all), or how well it flows at 40 degrees below zero, which is a temperature big planes face for hours as they cruise in the stratosphere.

Because fuel quality has such importance to safety, some energy experts thought aviation would be the last to switch. “For 40 years we had the philosophy we’d be the ones using the last drop of oil,’’ said Carl E. Burleson, director of the Federal Aviation Administration’s Office of Environment and Energy.

But compared to the market for gasoline or diesel, the market for jet fuel is simpler, industry experts say.

The number of fueling stations and customers are both much smaller than for motor vehicle fuel, making marketing easier. The number of engine manufacturers is smaller, too, so there are fewer parties to convince when switching to something new. And unlike the specifications for gasoline, which vary from state to state and country to country, there is a single standard for jet fuel, regardless of where it is sold.

As with substitute motor fuels, though, substitute jet fuel has mixed environmental implications. European carriers have tested fuel made from palm oil, but recent studies have persuaded some environmentalists that clearing tropical jungle to make space for palm plantations is a mistake, releasing more greenhouse gases than the new fuel will save. And the only petroleum substitute in common use now is made from coal, a switch that can save money and petroleum but makes greenhouse gas problems worse.

The precise carbon effect of using algae, jatropha or other substitutes will be studied closely and probably litigated, because airlines say they want to use such fuels to meet European regulations taking effect in the next few years, which will force them to cut carbon output or buy carbon allowances.