Increasing alarm over pollution and the eventual depletion of oil reserves are causing greater interest in alternative fuels. As part of this trend, University researchers are studying coal to help ease the transition to a post-oil society.

Funded by the Department of Energy, four faculty members and four graduate students are involved in three different projects.

"One is on the production of liquid fuels from coal. The second project is on processing coal together with petroleum, and the third project is on the high temperature stability of jet fuels, some of which can be made from coal," said Harold Schobert, associate professor and chairman of the University's fuel science program.

Coal reserves are expected to long outlast oil reserves and are abundant in the U.S. while much of the oil used domestically must be imported, Schobert said.

"Something like 51 percent of the petroleum used in the United States is imported. . . . Roughly one-quarter of all the coal in the world is in the United States," he said.

The researchers are concentrating on the chemistry behind the processes rather than producing large amounts of fuel.

"We're not going all out to get a complete conversion to liquids or to make gasoline or anything. We're really trying to understand what happens when the coal comes apart; how we can intervene in that process to help the formation of liquids," Schobert said.

In the coal liquefaction process, the coal is first impregnated with a catalyst to help the process take place. Then the coal is mixed with a liquid to have it suspended in a slurry.

The mixture is then reacted in the presence of hydrogen gas at fairly high temperature and pressure. After that, the unreacted coal and the ash residue are separated from the liquid.

"At that point you have a liquid that contains a whole variety of different things and what we do . . . is just separate that by different solvents," Schobert said.

University researchers have made several advances in refining the process.

"One of the things that we have contributed to at Penn State is understanding how to reduce the requirements for temperature for the reaction," Schobert said.

"One of my students, I think, is on the verge of coming up with some very interesting findings on how some of these materials in the liquid phase either help to dissolve the coal or help to shuttle the hydrogen from the gas into the coal particle as a catalyst," he added.

Caroline Burgess (graduate-fuel science) has been working with the coal liquefaction research.

"There are three broad areas that (the liquid fuel) could be used (in). One is simply as a fuel oil. A second would be as a diesel fuel. And then a third would be a gasoline or potentially as a jet fuel," Schobert said.

Even though this process is not currently used in industry, it will have tremendous value in the future, Burgess said.

"The kind of work they do at the research level is to try to improve conversion and the quality of the liquid that you produce so that if there is a time that we have to use it, we'll have the technology available," Burgess said.

In the second project, researchers are studying how liquid fuels are formed when coal and petroleum are processed together. This process has advantages over coal liquefaction because it could be used in existing power plants.

"There's much less lead time on getting liquid fuels from coal by co-processing than there is just starting from scratch with a coal liquefaction industry," Schobert said.

The co-processing also produces more liquid fuel than the researchers had originally expected.

"There's some kind of synergistic effect going on that no one understands yet," he added.

The third project, which focuses on jet fuel, concentrates on the surface of an airplane heating from friction during flight. One way to prevent damage from this heat build-up is to circulate the plane's fuel under the surface to cool it.

"The problem is that some materials when they are heated to very extreme temperatures could decompose and form solid plugs of carbon. Obviously, if one of those plugs the fuel line, you're not going to fly very far," Schobert said.