The Air Force, meanwhile, plans to certify its entire fleet of aircraft on Fischer-Tropsch process synthetic fuels derived from methane or coal by 2011 and plans to purchase enough such fuel to power at least 50 percent of the fleet in the continental U.S. by 2016. Tests began in November on the performance of the purer synfuel in the jet afterburner engines that are used for supersonic flight.
"That's about 400 million gallons [1.5 billion liters] of fuel," Anderson says, compared to 281,000 gallons [1.06 million liters] purchased this year and an estimated 500,000 gallons [1.9 million liters] next year. "It may only be marginally [environmentally] better in 2016. Carbon neutral? Probably not."
Although such synfuels may actually increase greenhouse gas emissions, depending on how they are produced, they will deliver some independence from the tyranny of petroleum. "The coal in the ground in the U.S. at current use will last 400 to 500 years. If you double, triple or quadruple the use of coal, it won't be 400, of course, it'll be 100 or 50 years," Anderson notes. "But it's 50 more years to get to the carbon-free economy."
Before then, the impact on Earth's climate can be limited by blending relatively small amounts of biofuels into such synfuels—an option DARPA, for one, rejects for logistical reasons—or capturing the carbon dioxide from synfuel production and using it to enhance the growth of the plants to be turned into fuel. "Put as little as 20 percent biofuel into nonrenewable fuels—coal-to-liquid and gas-to-liquid—you can be carbon neutral in a mix," CAAFI's Altman says.
Such a 20 percent mix would not require any modifications to existing aircraft engines or infrastructure, Green Flight International's Rodante says. "Jet fuel and biofuel mix is something that is easily done," he says "I don't believe 100 percent biofuel is the answer."
Oil prices at $100 per barrel are already well above the $40 per barrel level at which synfuel producing facilities break even, and even the $70 per barrel level that might make carbon capture economically feasible. "The biggest challenge is production capacity—and staying the course," FAA's Maurice says. "If the price of crude were to drop, can we sustain the interest?"
Still, the combination of factors involved: energy security, diversity of supply and the environment may sustain commercial aviation's interest, though its overall goals are smaller—certifying synfuel blends next year, full synfuels by 2010 and biofuels in 2013. "There is an underlying demand for something better than $90 per barrel oil, that has better domestic supply and can help cope with increasing environmental pressure," ATA's Heimlich says. "I have yet to see that silver bullet magic fuel."
In the interim, many airlines are offering ways to offset the greenhouse gas emissions associated with air travel, such as U.S.-based Delta Air Line's program with The Conservation Fund to plant trees in return for $5.50 that passengers are given the option of adding to the price of a domestic round-trip ticket or $11 for international round-trip flights. Britain-based Virgin Atlantic has a similar agreement with myclimate (a Swiss offset provider), who uses added flyer fees, which vary depending on ticket price, to fund renewable energy projects in developing countries such as India. It remains unclear, however, how much such passenger-funded partnerships do to alleviate climate change and they are a poor substitute for a carbon-neutral alternative jet fuel.