DURBAN, South Africa—My share of the carbon dioxide my flight to Johannesburg emitted over 15 hours amounted to 1,391.3 kilograms, according to the helpful information provided by South African Airlines. Add a dollop of 53.8 kilograms of CO2 for the jet jaunt to Durban and you can see that the aviation industry—and the Durban climate talks—have an emissions problem.
In fact, flying now accounts for some 2 percent—and growing fast—of global greenhouse gas emissions, although the industry has pledged to stop that growth by 2020. According to the aviation industry, a full 80 percent of the roughly 650 million metric tons of CO2 annually emitted by aircraft are from those flying more than 1,500 kilometers (like my trip from New York City to Durban) for which there is no alternative mode of practical transport. And, given the energy density of kerosene, there really is no alternative to liquid fuel either—with the exception of lightweight solar-powered drones, electric planes cannot get off the ground. As for hydrogen, it is hard to carry enough of it and still have space for passengers, too.
That's why the U.S. military, a slew of airline companies, Boeing and others have invested heavily in jet fuel made from plants—the oils provided by weedy camelina or hardy jatropha shrubs or even algae. The fuels have successfully passed all trials—even delivering more thrust per gallon—and have now entered regular commercial use in the U.S. and Europe, promising to cut CO2 emissions by 80 percent, albeit at a premium price. The U.S. Federal Aviation Administration is giving out $7.7 million in contracts to such jet biofuel–makers.
"Everybody wants a solution to oil," says Jigar Shah, CEO of the Carbon War Room, an organization founded by Virgin Airlines founder Sir Richard Branson and others to combat climate change. "Aviation is where it's going to come first."
Unfortunately, there's a problem. As much as ethanol from corn turns out to be a bad biofuel idea, the climate-friendly value of these bio-jet fuels depends largely on how they are produced. A fuel made from palm oil turns out to be worse for greenhouse gas levels in the atmosphere than jet fuel refined from petroleum because it involves clearing rainforest or peatland. To help solve this problem, the Carbon War Room has launched RenewableJetFuels.org, which ranks all biofuel companies on sustainability, among other criteria.
"We need to ensure that these fuels are made in a way that doesn't put pressure on ecosystems that are already stressed," says Suzanne Hunt, who is leading the Carbon War Room's aviation effort. "They must not put pressure on food security and we must make sure the greenhouse gas reductions are real and verified."
Per the Carbon War Room's main criteria of scalability (Can it be made in bulk?); sustainability (Can it be made with minimal environmental damage?); and economic viability (Can it be made at a profit?), the top five producers include: Lanzatech, SG Biofuels, AltAir, Solazyme and Sapphire—all of which have already provided biofuels to fly jets.
All of these fuels cost more than petroleum-based jet fuel. "For airlines, a third or more of the operating costs are fuel," Hunt notes, arguing that locking in bio–jet fuel at a consistent price will help airlines hedge that cost. "The E.U. including aviation under the cap [of its emissions trading program] is a major incentive."