There are no cheap or easy solutions. Lighter materials, new fuels and other innovations that promise to make planes more environmentally friendly mean more expense and development time. That includes the billions that engine makers are spending to develop new products.
All that could make it hard for the manufacturers to offer the discounts that their big customers have come to expect, potentially wiping out the savings that such planes might offer.
“It’s a bitter split,” said Mr. Williams of Airbus.
Mr. Bisignani said the industry was late to realize it needed to do more to stress its environmental credentials, leaving it open for attacks from environmental groups and threats of new taxes from Europe and elsewhere.
Some executives here said the criticisms were unfounded. “Aviation should not be treated as a pariah,” Tony Tyler, chief executive of Cathay Pacific, said at the environmental conference. “Everybody understands our obligations. Everyone is taking it very seriously.”
The new focus this year is in sharp contrast to the Farnborough show in 2006, when Boeing’s technology experts insisted in staff meetings that it was impossible to develop fuels that could substitute for the kerosene that powers jets.
Now, Boeing is conducting tests with four airlines — Virgin Atlantic, Japan Air Lines, Air New Zealand, and Continental — to see what may work best as an alternative fuel. British Airways, meanwhile, has invited energy producers to bring it fuels that it will test in laboratory conditions, its chief executive, Willie Walsh, said here.
Corn-based ethanol is out of consideration because it freezes at high altitudes and does not provide the power a jet needs.
For its part, Boeing wants a fuel that does not threaten the food supply, taint water or require that land be cultivated, said Billy M. Glover, Boeing’s director of environmental performance.
Scott Carson, chief executive of Boeing Commercial Airplanes, likens the industry’s quest for suitable biofuels to efforts to send a man to the moon.
“We didn’t know how to do that then; we don’t know how to do this now,” Mr. Carson said, in a video that runs continuously at Boeing’s display. But, he added, “we’ll do it, just like we did then.”
Development efforts are “so promising, and so close” to developing a new biofuel that could be derived from algae or other plant life, like Jatropha, a tropical plant whose seeds are rich in oil, Mr. Carson said Tuesday.
The algae doubles in size every 24 hours, said Darrin Morgan, the director of business analysis for environmental strategy. (He looked pained when asked if the plant life in the Boeing display was genuine. “It’s the real deal,” he said. “We wouldn’t give you green food dye.”)
New fuels are just part of the effort. Engines are an important element, since they can yield improvements in fuel economy and reductions in carbon emissions. General Electric showed a new engine, developed with a French partner, Safran, which it said should be ready in 2016.