Coal: The New Diesel?

When it comes to alternative fuels, you've read about ethanol, hydrogen and biodiesel. But, are you ready for a new fuel so abundant it could help the United States achieve energy independence and provide hundreds of years of transportation fuel — even as it lowered greenhouse gas emissions?

If you are, it is time to start thinking about coal — not your grandpa's coal, but liquid coal. More precisely, it is coal that has been converted to a liquid diesel fuel that is sulfur-free, emits fewer greenhouse gases than petroleum diesel and uses less energy to produce than ethanol.

"It is a natural fuel to address our energy concerns," says Corey Henry, a spokesperson for the Coal-to-Liquid Coalition, a consortium of coal producers, energy consumers, labor unions and coal-to-liquid (CTL) producers.

The U.S. Dept. of Energy estimates the nation has 286 billion tons of coal, which represents 95% of the nation's energy reserves, compared to 2 and 3% for oil and natural gas, respectively.

Coal itself is an inefficient source of energy that generates greenhouse gases and other pollutants when burned. Converting it to liquid diesel, however, turns it into an efficient form of energy that is very environmentally friendly. It produces minimal greenhouse gases and contains no sulfur — a principal component of particulate emissions.

Technology developed in 1920s

CTL technology has been around for more than 80 years and was explored commercially twice before — just after World War II and during the oil embargo of the 1970s. The discovery of cheap oil in the Middle East doomed the first attempt; the end of the oil embargo killed the second. Now, with oil prices stuck above $60 a barrel, developers and legislators are dusting off the manuals for the CTL process.

"CTL is commercially viable when oil is above $40 a barrel and most analysts predict oil won't fall back to that level any time soon, if ever," Henry says.

CTL is also becoming more attractive as ethanol loses some of its luster due to its high production costs, inferior gas mileage and its impact on corn prices. "The idea is catching on because [CTL] doesn't raise the price of beef or tortillas, because we have plenty of coal and because it keeps money in America," says John Rich Jr., president of Waste Management & Processors, Gilberton, PA, which has been advocating for the technology for more than a decade. Rich's firm has more than 100 million tons of culm, or waste coal, that it wants to convert to fuel using CTL.

While promising, CTL's future is far from certain. Its proponents will have to overcome coal's poor public perception, as well as environmentalists' negative knee-jerk reaction to anything related to coal.

Supporters are optimistic nonetheless. "We think there is a real appetite out there to lessen our dependence on foreign sources of fuel," says Henry. "It is a matter of awakening people to the technology. When they learn about it, they are surprised and heartened that we can convert this abundant resource into a clean fuel."

The most popular method for creating CTL diesel is the Fischer-Tropsch (F-T) process, which was developed by German engineers in the 1920s and has been a significant source of transportation fuel in South Africa since the 1980s.

In the F-T process, coal is heated to create a gas that consists primarily of carbon monoxide, hydrogen and carbon dioxide. The carbon dioxide is then removed and a metal catalyst is used to convert the remaining gas to a liquid that can be refined for use as diesel fuel, jet fuel and industrial chemicals.

Fewer emissions than oil-based diesel

The resulting fuel generates few particulate emissions because it contains no sulfur and few aromatics. Tests have shown that it generates 50% fewer hydrocarbon emissions, 50% less carbon monoxide and 30% fewer particulates than petroleum-based diesel. Like many diesel fuels, there are issues with lubricity and cloud points, but they can be remedied with additives.