Flying the Coal-Fired Skies
By Catherine Price
In the not-so-distant future, cars could run on electricity, power plants on wind and solar energy, and city buses on zero-emission hydrogen fuel cells. But airplanes? Those just might run on coal. 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.
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.
One good thing about transforming coal into jet fuel is that we know how to do it. In the 1920s, German scientists figured out a method for turning raw materials such as coal and natural gas into liquid fuel. It essentially involves steaming the coal to produce a hydrogen-and-carbon-monoxide gas, and then, through something called the Fischer-Tropsch process, exposing that gas to a series of catalysts to convert it to a liquid fuel. Hitler used the technique to power Germany in World War II, and during apartheid, when South Africa was facing embargoes, its government tweaked the process so that it could produce jet fuel as well.
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How to Fly on Coal: 1. Take coal. . . 2. Steam it to form “syngas”. . . 3. Expose that to catalysts. . .4. And voilà: jet fuel John MacNeill
Last September saw the launch of the Sustainable Aviation Fuels Users Group, a coalition of Boeing, the NRDC, and several other airlines and environmental groups that aims to encourage the development of low-carbon fuels. In the meantime, the American military might very well start powering its future using the hydrocarbon fuel of the past.
Full article at:
http://www.popsci.com/node/31142