Coal makes jet fuel

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University fuel scientist has created a high quality jet fuel derived from at least 50 per cent bituminous coal and successfully used it to power a helicopter jet engine.

Harold H. Schobert, professor of fuel science and director of Penn State's Energy Institute, said that because the fuel is 50 per cent derived from coal, it could reduce the US's use of imported petroleum for jet fuel by half. "We have shown in tests that the mix can go to at least 75 per cent coal," he said.

The fuel, provisionally designated JP900, is produced in one of two processes under investigation by Schobert. The process uses light cycle oil (a petroleum by-product) and coal-derived refined chemical oil, which is a by-product of the coke industry. The researchers mix the two components and add hydrogen. When distilled, jet fuel comes off as a distillate.

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.

"The combustion tests showed that JP900 meets or exceeds almost all specification for JP8 and Jet A," Schobert said. JP8 is a military jet fuel and Jet A is a standard jet fuel used since the 1950s.

The tests showed that JP900 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 sulphur free. From an energy point of view, JP900 produces almost exactly the same output as JP8.

Not only does JP900 meet most of the specification for JP8, but it also has the high flash point required of JP5, a naval jet fuel and the thermal stability of JP7, a high performance fuel.

The next target for the project is 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 1,900 litres of fuel in a pilot plant operated by Intertek. Schobert would now like to produce about 17,000 litres of the fuel for future testing by the US Air Force and others.