Once reluctant to believe that alternative energy made any sense in jet airplanes, Boeing now ponders how to take the biofuels revolution off the ground.
The world's largest airplane maker is working with fuel developers from around the world to find the holy grail of alternative fuels: one that will shrink jet flight's substantial environmental footprint without requiring an overhaul of the world's existing airplane fleet.
"Two years ago, we were quite skeptical of this whole area, because we thought there were too many challenges," said Bill Glover, environmental-strategy director for Boeing's commercial plane division. "Then we started to see a few things we hadn't seen before, people entering the field looking at alternatives, all kinds of feedstock."
Sometime next year, the company, in partnership with Virgin Atlantic and engine maker GE Aviation, plans to fly a biofuel-propelled 747.
The company is testing biofuels from different origins, ranging from soybeans a well-established source of biodiesel to algae.
The perfect compound would help stave off global warming without compromising the industry's growth.
"The first big step is to have a fuel that will go into today's airplanes and today's infrastructure seamlessly," Glover said.
But it's not an easy task. First, unlike ethanol, the ideal fuel would need to pack the same energy punch that fossil fuels do. Second, it must remain liquid at the low temperatures that surround an aircraft in flight biofuels tend to solidify more quickly than their fossil-derived equivalent.
Third, producing it in quantities to feed jets' enormous appetite must be environmentally sustainable which bodes ill for fuels derived from land-hungry crops such as soybeans.
There's hope, though, in futuristic crops such as algae, Boeing executives say.
A Seattle-Washington, D.C., flight consumes 29 gallons of jet fuel per passenger, says Boeing. That would require a half-acre of soybeans.
"You would have to plant an area the size of Florida with soybeans to provide a 15 percent blend of jet fuel" for the whole U.S. aircraft fleet, said Dave Daggett, who heads energy and emissions research at Boeing Commercial Airplanes' product-development unit. "Clearly that's not going to be appropriate."
Currently, the airline industry is responsible for about 11 percent of greenhouse gases emitted by the U.S. transportation sector, while automobiles account for 56 percent, according to a Federal Aviation Administration document.
But aviation's share of the greenhouse-gas pie is poised to grow, as air travel increases and ground vehicles use more alternative fuels like ethanol and biodiesel.
Higher fuel costs and growing political pressure are also driving airlines' interest. New aircraft technology is one response: Boeing's 787 jet produces 20 percent lower emissions per passenger than similar-sized planes.
Alternative fuels, however, are more difficult to implement in planes than in cars, experts say. Safety is a prime concern.
"Any change in fuel specifications is a huge issue for the industry," said Paul O'Neill, a London-based airline expert with Deloitte. "If you get adulterated or bad fuel, the aircraft might drop out of the sky."
Boeing estimates that biofuels could reduce flight-related greenhouse-gas emissions by 60 to 80 percent. That figure takes into account not only a lower emissions rate, but also the carbon dioxide absorbed by the vegetable crops used in producing the biofuel.
Airlines will most likely start by blending small quantities of biofuels with existing jet fuel, and increase the level as availability increases, said Daggett.
The fuel Boeing seeks in its testing would contain at least 20 percent biofuel, but ideally 50 percent.
Continental Airlines Flight Demonstrates Use of Sustainable Biofuels as Energy Source for Jet Travel
Boeing 737-800 equipped with CFM International CFM56-7B engines demonstrates first sustainable biofuel flight by a commercial carrier using a two-engine aircraft.
Airplanes have a useful lifespan of 30 to 40 years, and their manufacturers want to ensure they have fuel until the end, chemical engineer Expedito Parente explains to Tierramérica. Three decades...
Overall life cycle greenhouse gas emissions estimated to be reduced by 60 percent to 80 percent.