Coal in your car's tank: American-dug coal could be altered to produce clean-burning fuels for our vehicles. Here's how we could do it, and what might stop it from happening

New American, The, June 9, 2008 by Ed Hiserodt

In 1943, when Germany had virtually no sources of petroleum to fuel its Luftwaffe, U-boats, and Tiger tanks, its scientists (arguably among the best in the world at that time) didn't turn to solar and wind power. Evil does not equate to naivete. Hitler's technical advisers turned to another energy source to keep their Wehrmacht running steadily for several years without petroleum. They used the Fischer-Tropsch process to convert coal into diesel fuel and employed the Bergius hydrogenation (or liquefaction) process to convert coal into aviation gasoline and high-quality truck and automobile gasoline.

Coal-to-liquid Technologies

Gasoline and diesel fuel are hydrocarbons. The name gives us a clue as to how to convert coal to liquid fuel: combine hydrogen and carbon. Hydrocarbon fuels are designated by the number of carbon atoms in their molecules. For example, methane, the main constituent in natural gas, has one carbon and four hydrogen atoms. Ethane, butane, and propane are gaseous at room temperature and have two, three, and four carbon atoms respectively.

There are many hydrocarbons, and each has its own unique properties. Pentane, hexane, and heptane are liquid hydrocarbons but not desirable as fuels for internal-combustion engines as they have low ignition temperatures and cause "knocking" or premature combustion that can seriously damage an engine. Octane, with 8 carbon and 18 hydrogen atoms, is the optimum for standard engines, while cetane with 16 carbon and 34 hydrogen atoms is most desirable as a diesel engine fuel.

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Nothing about the chemistry of coal has changed since WWII, and it is still possible to synthesize fuel from coal, which ranges from about 65 percent to 95 percent pure carbon. All that's required is hydrogen, heat, and pressure. Worldwide. such production is done only in limited amounts although one country is a significant producer: South Africa. Just as the Nazis were isolated from petroleum sources during WWII, South Africa's policy of apartheid brought about an oil boycott from most sources. To survive, they adopted the Fischer-Tropsch process to convert their substantial coal reserves into gasoline and diesel fuel. This is no pie-in-the-sky "someday" technology. The Sasol Ltd. plant in Secunda, South Africa, alone converts coal to 150,000 barrels (6.3 million gallons) of liquid fuel each day.

The question arises: "Why, if the process is relatively simple, isn't more coal converted into oil'?" For years, the answer to that question was cost. It was simply too expensive compared to pumping oil out of the ground, reported to cost the Saudis less than $1 per barrel. Robert Wright of the Department of Energy said in 2007 that coal-to-liquid technology would only be economical once oil prices were at $40 to $50 a barrel. Now that prices are well above that mark and will likely remain there, the problem has become the environmentalists who fear pollution above economic hardships brought on by high-priced motor fuels. But what if we can all have our cake and eat it too?

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Taking Pollution Out of Coal

The Fischer-Tropsch coal-to-liquid (CTL) process has three reactions to yield hydrocarbon fuels. These reactions require a great deal of heat, heat derived from coal combustion. This process is referred to as Indirect Liquefaction. A major disadvantage of the technique is that the amount of coal used for heat in the coal-to-liquid process is greater than the amount converted to fuel. As a result, this process produces large amounts of ash, fly ash, sulfur dioxide, and nitrogen oxides, not to mention a waste of coal.

The Direct Liquefaction process developed by Nobel Laureate Friedrich Bergius in 1921 requires only one step where hydrogen is combined directly with pulverized coal under high pressure and temperature to produce various hydrocarbons depending on process variables. Since there are no naturally occurring sources of hydrogen like "hydrogen wells," the [H.sub.2] in existing coal-to-liquid plants (and in WWII Germany) is produced by the same chemical reactions used in the initial step of the Fischer-Tropsch process, i.e., it is obtained from heating coal with high-pressure steam producing hydrogen and carbon monoxide (C [H.sub.2]O [right arrow] [H.sub.2] CO).

The bulk of pollutants created from direct liquefaction, the Bergius process, are created in the making of hydrogen for the process, but the creation of these pollutants can be largely avoided by separating the hydrogen with heat from a new generation of super-safe nuclear reactors.

While anti-nuclear activists have stymied the construction of any new power reactors in the United States for over 30 years, they have not been able to stop the development of new reactor technology, much of which has been done outside the United States. Third-generation modular reactors are designed to make meltdowns physically impossible. Among these developments is the "Pebble Bed Modular Reactor" that uses several hundred thousand baseball-sized fuel spheres, each of which contains 15,000 coated, grain-of-sand-sized fuel kernels. The pyrolytic graphite and silicon carbide layers coating the fuel kernels have melting temperatures far above that of the maximum equilibrium temperature of the reactor, making a meltdown impossible.