A synthetic jet fuel comparable to Jet A or military JP 8, but derived from at least 50% bituminous coal, has successfully powered a helicopter jet engine, according to a Penn State fuel scientist.
The JP 900—on which the Penn State team has been working since the early 1990s—is produced by hydrotreating a mixture of light cycle oil—a petroleum byproduct—and coal-derived refined chemical oil—a distillate derived from the refining of coal tar (a by-product of the metallurgical coke industry). The jet fuel comes off as a distillate.
The fuel has superior resistance to decomposition at high temperature, and it designed to be stable at 480°C or 900°F (hence the designation JP-900). Penn State originally began the research in the search for a very thermally stable fuel for the next generation of high-performance aircraft.
The current situation with energy prices and sources of petroleum are providing a new perspective on the potential benefit of the fuel.
Because the fuel is 50% derived from coal, it could reduce our use of imported petroleum for this purpose by half. We have shown in tests that the mix can go to at least 75% coal.—Harold Schobert, Penn State professor of fuel science and director of the Energy Institute
The process can be carried out in existing refineries with some retrofitting and small amounts of the leftover components will feed into various portions of the petroleum stream. The lighter portions will go to the pool of chemicals that make gasoline and the heavier ones go to the diesel or fuel oil streams.
Combustion tests showed that JP 900 meets or exceeds almost all specification for JP8 and Jet A. These tests showed that JP 900 has a flash point higher than required for JP8, a lower viscosity and freezing point and a higher smoke point.
The coal-based fuel is lower in aromatics—such compounds as benzene and toluene—than conventional jet fuels and is almost sulfur free. From an energy point of view, JP 900 produces almost exactly the same BTU as JP8.
Not only does JP 900 meet most of the specification for JP8, but it also has the high flash point required of JP5, naval jet fuel and the thermal stability of JP 7, a high performance fuel.
The fact that our fuel is almost dead on to JP 8 is something that the Air Force likes. This fuel was intended to be a high heat sink fuel, which it is, but it can also be used in existing engines.—Harold Schobert
The project now targets coal-based replacement for existing fuels with the hope that this will interest both commercial and military users. So far the Penn State project has produced 500 gallons of fuel in a pilot plant operated by Intertek of Warren, Pa. The Penn State researcher would now like to produce about 4,500 gallons, or about 100 barrels, of the fuel for future testing by the Air Force and others.
Funding for the research comes form the U.S. Air Force Office of Scientific Research and the Department of Energy.