Alaska Airlines begins an expensive trial of biofuel-powered passenger flights Wednesday, billing the 75 trips as a pioneering effort to "fly cleaner" and to kick-start a nascent renewable-energy economy.

Travelers on the first two flights — to Washington, D.C., and to Portland — will get a flier titled "Welcome to Greener Skies" as their plane takes off from Seattle-Tacoma International Airport powered by a blend of regular jet fuel and 20 percent biofuel made from used cooking oil.

It's part of a worldwide push by airlines to address claims that plane emissions contribute to global warming.

United Airlines flew the first biofuel-powered passenger flight in the U.S. on Monday from Houston to Chicago.

Never mind that burning biofuels produces as much carbon emissions as regular jet fuel.

It's counted as "greener" because the carbon dioxide emitted is from renewable sources or, as in this case, from waste byproducts that would be produced anyway.

The lure of "green jobs" is touted as an added plus. In a statement, Sen. Maria Cantwell, D-Wash., chairwoman of the Senate's aviation subcommittee, said a biofuel economy "has the potential to employ thousands of Washingtonians."

Yet the fledgling industry is far from proving its economic viability.

Alaska paid $476,000 for 28,000 gallons of biofuel to power the flights over the next 11 days. At $17 per gallon, that's six times what it pays for regular jet fuel.

Billy Glover, Boeing vice president for the environment and aviation policy, said Alaska's move "is an investment in the future, to signal to the market that they are serious about wanting this to come to scale and to a price point that's affordable."

For the airline industry, the appeal of biofuels — produced from oily "feedstocks" including camelina oil, jatropha seeds, algae, used cooking oil or animal fats — is driven by relentless pressure from environmentalists.

Though aviation contributes only an estimated 2 to 3 percent of the world's carbon-dioxide emissions, that's likely to grow as air travel rapidly expands in the developing world.

To mitigate the impact, Airbus and Boeing are producing ever more fuel-efficient planes. And Alaska Airlines is a leader in efforts to save fuel by streamlining air routes using satellite-based navigation.

But Megan Lawrence, Alaska's managing director of government and community relations, said a bolder step is needed.

"Basically we can only get so far as an airline and an industry focusing on efficiency efforts," said Lawrence. "Where we are going to get the real improvement is from changing the fuel we use."

Boeing catalyst

Five years ago, Boeing hosted a seminal industry meeting on biofuels in Everett. In 2008 it conducted the world's first airline test flight of biofuels with Virgin Atlantic, followed by further test flights with other airlines around the world.

Biofuels were finally certified as safe jet fuel only in July, making it possible to fly passengers in biofueled planes.

The main rationale for this push — that biofuel is considered cleaner than regular jet fuel — is not self-evident.

"The emissions out the tailpipe are the same," Glover said. "The reduced carbon footprint is on a life-cycle basis."

Scientists working with the Roundtable on Sustainable Biofuels — a Switzerland-based international organization of biofuel stakeholders and environmental groups — make complex calculations to determine the net carbon footprint over the entire life span of an energy source.

Crops absorb carbon dioxide as they grow, and the biofuel produced from them releases that same gas when burned. The net increase in carbon dioxide is small, coming mainly from the processing and transportation of the fuel.

As for animal fats and used cooking oil, carbon dioxide emitted in the ordinary life cycle of such grease is assigned to food production. What would otherwise be waste is counted as carbon-free.

Subsequently turning the used cooking oil into biofuel produces about half the carbon emissions of jet fuel, said Glover.

With Alaska using a 20 percent blend on its demo flights, that translates on paper into a saving of 10 percent in carbon emissions.

The airline estimates the life cycle carbon-emissions savings on its 75 trial flights as "the equivalent of taking 26 cars off the road for a year."

And if Alaska flew all its planes on a similar blend for a whole year, the "emissions savings would represent the equivalent of taking nearly 64,000 cars off the road," the airline said.

The airline had to search hard for enough supply to cover 75 flights. A study last year backed by Alaska and Boeing concluded that this state has the potential to produce sustainable biofuel feedstocks, but the airline couldn't find any close by.

Boeing's Glover said that's because the biofuel supply chain is "in the early stages."

"We have spot availability," he said. "Alaska is working with what's available."

Alaska finally bought from Dynamic Fuels, a joint venture between Springdale, Ark.-based processed-meat giant Tyson Foods and Tulsa, Okla.-based Syntroleum, which produces biofuels.

While biofuels are often promoted as the fruit of fields of waving crops or ponds of translucent green algae, Bob Ames, Tyson's vice president of renewable energy, said Dynamic currently uses only "the dirtier types of feedstocks," namely animal fats and used cooking oil.

For Alaska, the fuel came entirely from the latter. "Think McDonald's fryer grease," said Ames.

At a plant opened a year ago in Geismar, La., fats, oils and grease are cleaned and distilled into a pristinely clear liquid, for now sold mostly as biodiesel for road and marine transport.

Dynamic Fuels lost $12.3 million in its first nine months, through June 30. Ames said that's "natural for a startup operation."

Both Ames and Boeing's Glover called for "supportive government policies" to create a biofuel supply chain. Ames said the cost of biofuel will come down as the industry gains scale.

Room to grow

Ames said he doesn't worry about Dynamic's ability to expand.

"In the U.S. if you eat chicken, beef and pork, there's a 1-in-4 chance it comes from Tyson Foods," Ames said. "We could build multiple plants literally from the feedstocks Tyson has internally."

Alaska's Lawrence conceded that the cost of biofuel now is unsustainable.

"We're paying a premium," Lawrence said. "This is putting our money where our mouth is and actually trying to stimulate some movement here."

Dominic Gates: 206-464-2963 or dgates@seattletimes.com