Yes, coal. The U.S. Air Force wants to create a synthetic-fuel industry that, unless something better comes along, will mine America’s massive coal supply (we have more than a quarter of the world’s known reserves) and turn it into enough jet fuel for half its domestic operations to run on a 50/50 blend of synthetic and regular fuel by 2016. By the Air Force’s logic, it has no choice. It uses more fuel than all the other branches of the military combined, burning through 2.5 billion gallons of the stuff in 2007 alone—10 percent of the total used by the entire domestic-aviation fuel market—at a cost of $5.6 billion. And although oil prices have dropped in recent months, no one expects the relief to last indefinitely.
Yet alternative fuels for aviation are hard to come by. The Air Force says it’s open to all sources of power for its fleet, but according to former assistant secretary of the Air Force William Anderson, petroleum, natural gas and coal are our only current options—and when you look at the U.S.’s resources, the choice is clear. “We’re not the largest holder of oil reserves, so that’s not a good option,” he says. “We’re not the biggest holder of natural gas. But we are the Saudi Arabia of coal.” So the Air Force is doing its best to spark a domestic fuel industry that would be devoted, most likely, to digging new coal mines and building the country’s first major coal-to-liquids (CTL) plants. To make the market bigger, it wants to convince the other branches of the military and even domestic airlines to run their fleets on liquefied coal, too.
From a purely martial perspective, the strategic benefits of this plan are obvious: The U.S. would use far less oil imported from countries it doesn’t get along with. But there are problems, like the fact that the plan could generate twice the carbon dioxide emissions of current fuels—making it, thanks to a special clause in the 2007 energy bill, illegal.
CTL proponents, aware that coal has an image problem, fend off criticism by saying that the fuel is actually “greener” than jet fuel made from petroleum. What they mean is that during the gasification process, jet fuel from coal is scrubbed clean of particulate emissions as well as sulfur dioxide and nitrogen oxide—the stuff that causes acid rain—so it is in one sense cleaner to burn. But that leaves out a crucial bit of information: Between mining the coal and burning the resulting jet fuel, coal-to-liquids fuel produces twice as much CO2 as the existing petroleum-derived fuel. The potential effect of creating a market for CTL fuels is frightening enough to environmentalists that last year Representative Henry Waxman, who now heads the House Committee on Energy and Commerce, added a clause to the 2007 energy bill—Section 526—forbidding the U.S. government from spending taxpayer money on fuels that emit more greenhouse gases than the fuels we’re already using.
That hasn’t stopped the Air Force from moving ahead with its plan—it simply says that the companies that produce the fuel will have to figure out a way to comply with Section 526. So while lobbyists for both the coal and petroleum industries work aggressively to get Section 526 repealed, potential CTL suppliers are looking into technology that could, theoretically, clean coal-based jet fuel enough that it’s the greenhouse-gas equivalent of petroleum.
There are a few ways to get there, none of them easy, including recycling CO2 by running it back through the Fischer-Tropsch process to produce more fuel (after all, carbon dioxide has carbon in it, the same energy source as fossil fuel), using the CO2 to grow oil-producing algae, or turning the carbon into usable industrial gases. The Air Force estimates that it will be at least a decade, however, before any of those technologies can be used at anywhere near a broad scale. More feasible is using CO2 for something called enhanced oil recovery—liquefying and pumping the CO2 into dying oil wells to push remaining oil to the surface. But the danger in that process is that it might contribute to the very problem it’s trying solve, because the energy required for liquefication will almost certainly come from carbon-emitting fossil fuels. Then there are long-term consequences to consider. Will the carbon dioxide leak out of the oil well? No one knows.
Ultimately, the question is this: Is it better to send American aviation down the road toward coal-based fuel without a clear idea of what to do about the extra carbon emissions, or to keep on burning billions of gallons of imported oil every year? The lack of alternatives makes this debate tricky. Finding renewable sources of jet fuel is “going to be tough, there’s no doubt about it,” says Tyson Slocum, director of the public-interest group Public Citizen’s Energy Program. “You can’t put solar panels on a jet airplane.”
The problem can even make committed environmentalists soften a bit toward oil. Henry Henderson and Shannon Fisk of the Natural Resources Defense Council suggest that we scrap liquid coal entirely and invest in oil-saving technologies that we already have, like hybrid and electric cars and trucks. That could free up more oil for jet fuel, lowering its cost and buying time to search for sustainable alternatives.
Catherine Price’s most recent article for Popular Science was “The Anonymity Experiment,” last March.