In what Virginia Gov. Charles S. Robb called a "breakthrough" for the coal industry, United Coal Co. has unveiled a liquid coal fuel that can power a truck with no modification of the vehicle's engine.

The company used a 50-50 mixture of liquid coal and diesel to operate a 25-ton coal truck, with Robb at the wheel, in the first public demonstration of the fuel here last week.

United's head of research and development, Richard Wolfe, said the test proved that "coal can be a viable alternative" to diesel fuel now being used in trucks, locomotives and large ships.

After piloting the truck a short distance, Robb said he believed the development was a "breakthrough" for the coal industry, and said its future applications are "almost limitless."

It will take about two years for the new fuel to be applied commercially, United officials said, but the Bristol-based coal firm hopes to use it to power its own fleet of coal trucks within a year.

Wolfe said the final fuel product will probably contain a mixture of 70 percent coal and 30 percent diesel.

"It's one of the most exciting developments in the coal industry," said Rep. Rick Boucher (D-Va.), who as a member of the House Science and Technology Committee has helped get funding for United's research.

Boucher said the new fuel would help the crippled coal industry by opening up new markets, thereby creating more jobs. Some southwest Virginia coalfields have unemployment rates of up to 20 percent.

"I think we're on the verge of changing the coal industry," Wolfe said.

Attending the demonstration were representatives of Norfolk Southern and CSX railroads, whose locomotives United hopes to run with the fuel.