Airlines tank up passenger jets with used restaurant cooking oil in an effort to make travel a bit greener.
Alaska Airlines flew 75 passenger flights last year that were fueled in part with recycled cooking oil.
The biofuel cost $17 a gallon -- about six times more than traditional petroleum-based fuel.
The demonstration was the largest yet in the United States that biofuels are a viable and environmentally friendlier alternative to conventional fuel.
It didn't smell like fried chicken when an Alaska Airlines jet took off from Seattle last November for a cross-country flight to Washington D.C. Yet some of the fuel flowing through the Boeing 737's engines had previously been used in restaurant fryers.
"We told our passengers at the gate before they boarded so they could reschedule if they wanted," said Alaska Airlines spokeswoman Bobbie Egan. "It felt like the right thing to do."
No one blanched over the prospect of used cooking oil flowing through their airplane's engines, a rational response since chemically speaking there was no difference between the processed biofuel and traditional petroleum-based gasoline.
"People were very supportive," Egan told Discovery News.
The recycled cooking oil was blended with conventional aircraft fuel and used in 75 flights. Alaska Airlines had wanted a 150-flight demonstration, but couldn't find enough cooking oil for them all.
Even pulling off 75 flights required some creative -- and expensive -- logistics. There wasn't enough used cooking oil and restaurant grease on the west coast, so a supplier tapped restaurants in the south, which apparently has a heartier business in frying foods.
"Clearly, it is not an ideal situation," Egan said. "In order for an aviation biofuel industry to be really kick-started, every region needs its own source."
That doesn't mean that Californians will blaze a green path into the skies by eating more fried food.
"There is no one solution. In order for the aviation biofuel industry to be viable, it needs to be varied," Egan said.
That could mean algae farms in the west, recycled cooking oil in the south. But no matter what the source, the price of biofuel needs to come down significantly to be competitive with petroleum gas.
Including transportation costs and processing, Alaska Airlines paid $17 a gallon for its recycled cooking oil, about six times the price of conventional jet fuel.
"We're very much in the early stages of this journey," Mike Hurd, director of environmental strategy for Boeing, told Discovery News. "Six years ago, no one thought biofuels would ever work in airplanes. It was viewed if not technically impossible, than improbable."
Boeing, an aircraft manufacturer, is working with its customers to help the industry cut the amount of greenhouse gases that are released into the atmosphere.
"If we can use plant-based matter in fuel, we allow customers to lower their carbon dioxide emissions as compared to jet fuel," Hurd said.