Airplane operators are growing thirstier for a new fuel.
The price of oil last week surpassed $100 a barrel, flirting with a record high. If the cost creeps much higher, it could leave some airplane operators parched.
Still, the soaring expense isn't curtailing global demand for commercial, general aviation, and military flights. So the search for alternative jet fuels is intensifying, and its progress will likely be propelled as several milestones are reached this year, ranging from researchers releasing a crucial analysis of alternative fuels' financial and environmental costs to aviation companies holding test flights to prove that some alternative fuels will work.
The latest demonstration run - by passenger carrier Virgin Atlantic Airways Ltd., in conjunction with aircraft manufacturer Boeing Co., engine maker GE-Aviation, and biofuel producer Imperium Renewables Inc. - was flown yesterday from London to Amsterdam.
The Boeing 747's test flight, which carried only technical advisers who recorded flight data for further study, marked the first time a commercial aircraft ran on a blend of 80 percent conventional jet fuel mixed with 20 percent of a biofuel derived from babassu and coconut oils.
The search for new fuels has rumbled along quietly for more than half a century, but potential alternatives to petroleum have proven significantly more expensive to produce, pump, or use.
Now, the sharply increasing economic incentive to embrace other fuels is coupled with mounting public concern over the depletion of natural resources and the emission of atmospheric pollutants that contribute to global warming.
Yesterday, Virgin's president, Richard Branson, said the test flight would supply "crucial knowledge that we can use to dramatically reduce our carbon footprint."
The last time the price of oil hit $100 a barrel, in inflation-adjusted terms, was 1980. That quickly caused a flurry of interest in finding alternative energy sources - until the price plummeted in the mid-1980s and damped the investments and the will to see research projects through, experts recall.
"In the past, the driver was just cost, finding something cheaper," said James Hileman, a Massachusetts Institute of Technology research engineer. "Now there's another driver: climate change."
While aviation accounts for less than 3 percent of greenhouse gas emissions, it has attracted a large share of criticism for harming the environment.
This spring, Hileman and other researchers at MIT's Partnership for AiR Transportation Noise and Emissions Reduction, or PARTNER, plan to release the results of their two-year analysis of the lifecycle costs and the environmental side effects of standard commercial aviation fuel, known as Jet A, and 10 potential alternatives.
The report is also expected to outline the options for developing large amounts of alternative fuels within a decade.
The professor, three research engineers, and two students who are working on PARTNER's alternative fuels project - launched two years ago with $560,000 from the Federal Aviation Administration, NASA, and Transport Canada - are developing software so the FAA computer model that airport planners use to predict emissions can now account for the effects of alternative fuels.
They include ultra low-sulfur Jet A, Jet A derived from Canadian tar sands, Jet A from Colorado oil shale, and soybean-oil "biojet."
PARTNER quantified the costs and environmental repercussions spanning each jet fuel's lifecycle - from harvesting the resource to producing it to transporting it to storing it to using it - and included local air quality, noise pollution, human exposure to hazardous materials, and global climate change.
PARTNER's report is expected to become the aviation industry's central model for analyzing the holistic costs of alternative fuels and provide a sturdier basis for making decisions about using them.
"It's the most significant and an essential tool that we need to have as we evaluate alternative fuels," said Richard L. Altman, executive director of the Commercial Aviation Alternative Fuel Initiative, a forum formed in October 2006 that brings together US aircraft manufacturers, US airlines, North American airports, and the FAA.
PARTNER declined to delve into the details of its findings since the draft report is still being reviewed, but Hileman said one of the big points is "there is no one silver bullet" that can replace Jet A or, for that matter, the military jet fuel JP-8.
That's because the limited supply of alternative fuels can't satisfy worldwide jet-fuel consumption, which experts estimate will reach 210 million to 231 million gallons a day this year and will grow 2 to 4 percent per year - even as older aircraft are replaced with more fuel-efficient ones.
More likely, he said, multiple alternative fuels will augment the supply of petroleum jet fuels and bring down the price, but not for quite a while, because new refineries and other infrastructure must be built.
Some of the alternative fuels PARTNER studied don't offer significant advantages.
For example, Canadian tar sands "are a wash at best but a detriment at worst compared to Jet A in terms of climate change," Hileman said.
Liquefying coal can be "a bad idea because it results in a doubling of carbon dioxide emissions."
Another option - removing sulfur, a carcinogen, from jet fuel - would reduce emissions that harm surface-level air quality but would cost more.
"There are options, but there's nothing quick and easy," Hileman said.
Several companies are testing alternative jet fuels this year. In addition to yesterday's Boeing-Virgin Atlantic demo, the aircraft manufacturer is planning a flight with Air New Zealand using a Boeing 747 burning biofuel.
Airbus also experimented with an alternative fuel in its A380 aircraft during a three-hour flight between England and France on Feb. 1 - staking its claim as the first to showcase a commercial aircraft powered by a synthetic liquid fuel processed from gas.
These demonstrations will give researchers more information on how effective each alternative fuel is and help determine whether these fuels or variations of them should be produced for commercial airliners.
"What you're seeing now is a pretty dramatic increase in the number of these types of tests occurring, in terms of the number of fuels and the number of different aircraft types," Altman said.
"It shows a dramatic increase in focus by the airlines."
Nicole C. Wong can be reached at nwong@globe.com.
