Continental Airlines flight 1403 made history when it landed at O'Hare International Airport in Chicago on Monday, becoming the first revenue passenger trip in the U.S. powered by biofuel.
The Boeing 737-800 burned a "green jet fuel" derived partially from genetically modified algae that feed on plant waste and produce oil.
In completing the flight from Houston, parent company United Continental Holdings Inc. won by two days the competition to launch the first biofuel-powered air service in the U.S.
On Wednesday, Alaska Airlines started 75 passenger flights along with its sister airline, Horizon Air, that will take place over the next few weeks using a biofuel blend made from recycled cooking oil. The 20% biofuel blend the planes will use will reduce carbon dioxide emissions 10%, Alaska Airlines officials said.
More U.S. airlines are expected to join the effort to fly cleaner — and eventually more economically — than the use of traditional petroleum-based Jet-A fuel allows, based on a crude oil price of $100 a barrel or higher, experts said.
But there are questions regarding how long it will take for biofuel to become an economical alternative to traditional fuel and what the cost will be for the financially struggling aviation industry.
Boeing Co. projects, for example, small-scale commercial production of new biofuels derived from algae, sewage sludge or municipal waste beginning in as soon as three years.
United announced Monday that it had signed a letter of intent with Solazyme Inc. of South San Francisco, which provided the biofuel for the Continental flight, to buy 20 million gallons of algae-derived biofuel annually. Delivery will start as early as 2014, officials said.
The move comes four months after international aviation regulators approved the use of biofuels. In recent weeks, several airlines in Europe have operated biofuel-powered flights. KLM Royal Dutch Airlines in June became the first airline in the world to operate a commercial flight on biofuels.
Part of the beauty of using advanced biofuels is that no modifications are needed to commercial airplanes; the biofuels are a drop-in replacement for high-octane Jet-A, officials said.
"You don't have any difference at all in terms of performance of the airplane or operations by the pilot," said Capt. Jackson Seltzer, a 25-year Continental veteran who flew Monday's flight to O'Hare from Bush International Airport in Houston.
The 737 was fueled with 60% traditional petroleum-based jet fuel and 40% aviation biofuel made from algal oil, officials said.
The technology converts inedible natural oils and wastes into a more environmentally friendly jet fuel that offers as much as an 85% reduction in greenhouse gas emissions compared with fossil fuels, officials said.
United officials declined to estimate how long it would take to integrate alternative fuels into their system, but they noted that the airline used 3.3 billion gallons of Jet-A in 2010 at a cost of about $13.5 billion.
Pete McDonald, United Airlines' executive vice president and chief operations officer, said the cost of Monday's biofuel flight was "about the same" as a regular flight.
The 20 million gallons that United plans to buy from Solazyme represents 0.6% of the airline's jet fuel consumption, said Jimmy Samartzis, United's managing director of global environment affairs and sustainability.
"The bottom line for us is this is another example of actions that are needed to be taken to commercialize advanced biofuel production," Samartzis said.
Solazyme officials, who dubbed their algae-derived fuel Solajet, shared the optimism.
"We founded the company in a garage in Palo Alto eight years ago," said Harrison Dillon, Solazyme's president and chief technology officer. "Today is a historic day and we've come a long way, but we have a lot of growth ahead."
Fuel accounts for the largest segment, 36%, of airline industry operating costs, according to the International Air Transport Assn.
The aviation sector, which was responsible for 2% of total carbon dioxide emissions in 2000, will increase its share to 3% by 2030, according to research by McKinsey & Co.