Once reluctant to believe that alternative energy made any sense in jet airplanes, Boeing now ponders how to take the biofuels revolution...

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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.

Boeing executives said the company is informally collaborating with leading Brazilian biofuels maker Tecbio, Aquaflow Bionomic of New Zealand and other fuel developers around the world. So far, Boeing has tested six fuels from these companies, and will probably have gone through 20 fuels “by the time we’re done evaluating them,” Daggett said.

Testing could wrap up in early fall, said a spokesman.

Boeing executives say the biofuel of the future also needs to be available in sufficient quantities and produced in a sustainable way.

“The biggest challenge right now is whether you can grow enough biomaterial to make enough jet fuel,” said Daggett.

It would take a lot of land to produce enough crops like soybeans to propel fuel-hungry jets. The increasing use of crops like corn and soybeans to produce ethanol and biodiesel is already stirring a controversy of its own. Some argue these biofuels have a negative impact on the environment and on food prices.

The solution could lie in algae, experts say. These slimy aquatic creatures not only absorb great quantities of carbon dioxide during their lifetime, but they are also the source of energy-rich oil that can be turned into fuel. Lurking in the depths of ponds, they take a lot less space than conventional horizontal above-ground crops — and they can live in brackish water. A huge algae bio-reactor — a series of chambers or ponds outfitted to boost growth — could supply more fuel in less space than other plants.

“Instead of needing all of Florida [for U.S. transport needs], you could provide the whole world’s fleet with biojet fuel if you had a bioreactor the size of Maryland,” Daggett said.

Daggett estimates that a pilot plant for algae-based fuel could be in place in a year or so. “I think within 10 years we could see biofuel produced from algae,” he said.

It’s likely, though, that different countries will find their own solutions. The nuts of the babassu palm, abundant in Brazil, offer a “pretty good yield per hectare” and could be an eco-friendly solution if used to reclaim land ravaged by deforestation in South America, Daggett said.

Ángel González: 206-515-5644 or agonzalez@seattletimes.com

Seattle Times reporters Kristi Heim and Dominic Gates contributed to this story.