We have been documenting that Coal can be converted into perfectly acceptable liquid aviation fuel, most recently in our reports concerning the approval, by international regulating bodies, and the subsequent commercial use of, South Africa Synthetic Oil Limited's 100% Coal-based jet fuel.
 
We have also previously reported on Penn State University's efforts to develop similar Coal-based aviation fuels, work that has been done, in part, in support of the United States Department of Defense strategic initiative to develop domestic supplies of fuel for military aircraft.
 
Herein, we present further, though somewhat dated, information concerning their achievements.
 
Brief, and somewhat repetitive, comment follows excerpts from the above link to:
 
"Coal Source Of Jet Fuel For Next Generation Aircraft
 
March, 2004 — New fuel for the next generation of military aircraft is the goal of a team of Penn State researchers who are demonstrating that jet fuel can be made from bituminous coal.

"On a pilot scale, we have produced thermally stable coal-based jet fuel," says Dr. Harold H. Schobert, professor of fuel science and director of Penn State's Energy Institute. "This coal-based fuel can absorb significant amounts of heat and remain stable to 900 degrees Fahrenheit."

The new fuel will not decompose at high temperatures to create the deposits of carbon, which foul valves, nozzles and other engine parts. The fuel will be provisionally designated jet propulsion 900 or JP900 because of this high temperature stability. The researchers are designing the fuel for the new generation of high performance engines in aircraft such as the F35 joint strike fighter and the U.S. Air Forces' VAATE program – versatile, affordable, advanced turbine engines. However, according to the researchers, it may be possible to use this fuel in conventional jet engines in current aircraft.

The front portion of a jet engine is an air compressor and the new engines compress air at higher and higher pressures generating larger amounts of heat. The outside air is not sufficient as a cooling medium, so the designers use the fuel itself as a heat sink, so high temperature stability is necessary.

"While power generation will remain the mainstay of coal use for many decades, coal does supply a molecular structure that has properties necessary for making high-temperature stable fuel," says Schobert.

Schobert; Suchada Butnark, former graduate student in fuel science; and Leslie R. Rudnick, senior scientist at the Energy Institute, worked on two processes to create JP900 from coal-based materials. One method relies on bituminous coal becoming fluid when heated. The researchers mixed bituminous coal with decant oil, a byproduct of petroleum refining, at normal pressures. When heated, the mixture becomes fluid and the liquid portion distills off and is collected as JP900. The remaining solid is coke, a valuable byproduct for making anodes for aluminum smelting or in making graphite.

"This process is a variant of a standard process used in petroleum refining," says Schobert. "We would really just need a mixer for the two components and then the process could be done in normal refinery operations."

The second process uses light cycle oil, another petroleum byproduct, and coal-derived refined chemical oil, a byproduct of the coke industry. The researchers mix the two components and add hydrogen. When distilled, jet fuel comes off as a distillate.

The Penn State researchers believe that they can carry out both processes in existing refineries. They plan in the next year to test the fuel in a jet engine at Wright Patterson Air Force base. Currently, the researchers are producing JP900 in 55-gallon barrel lots, but they hope in the future to test manufacturing with a run at United Refining in Warren, Pa.

The researchers are also working with the Air Force to develop an official specification for JP900. "Without a specification, no one will put this fuel in an engine," says Schobert.

One potential benefit with manufacturing these fuels in existing refineries is that 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 inclusion of coal-based compound in the petroleum steam will probably be beneficial in making gasoline and probably will not make any difference at all in the fuel oil stream," says Schobert. "What we do not know is how it will affect the diesel stream."

In addition to its high temperature properties, JP900 has a 10-degree Fahrenheit lower cloud point – the temperature at which a cloud forms over a liquid. This is a better cold weather fuel than either the Jet A or JP8 currently in use.

These coal-derived fuels also have no ash and very low sulfur. Refined chemical oil, derived from coal, has already had the ash removed. In the decant oil process, the coal would need to be pre-cleaned but would also produce a low-ash coke byproduct.

When it comes to coal, sulfur is often the most troublesome pollutant, but these processes can be as low sulfur as three parts per million, depending on the original sulfur content of the coal and the amount of hydrogen used. For higher sulfur coal, more hydrogen will allow fuels that are still low sulfur.

"We do not have much doubt now that we can do this," says Schobert. "We have a lot more to do and it will be expensive, but there is not much doubt that it will work."

The U.S. Air Force Office of Scientific Research funded this work. The U.S. Department of Energy is also funding some of the ongoing research."

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Based on SASOL's achievements, we now know that it is more than just "possible to use" Coal-derived "fuel in conventional jet engines in current aircraft".

It is being done.

However, note that PSU is, or was, only working to develop a Coal-based liquid fuel that could be blended into standard petroleum-based liquids, something that South Africa had been doing for decades, prior to the approval of their 100% Coal-based fuel.

And, Penn State's work seems to be based on older, solvent-refined Coal, or "SRC", processes, once practiced under US Government contract, as we've earlier documented, at a number of sites around the nation, including Catlettsburg, KY, and Fort Lewis, WA. 

Thus, there is some solid, purified Carbon residue, "coke", left by their process, which they propose to find use for in the making of anodes for aluminum refining.
 
We submit, instead, that if Penn State University's technology for producing jet fuel from Coal is in some way especially advantageous and worthy of practice, then the Carbon residue could be further processed by, for instance, WVU's "West Virginia Process" for direct coal liquefaction, which uses a hydrogen donor solvent, known as "Tetralin", which we believe is based on the primary Coal oil, Naphthalene, to liquefy and hydrogenate Carbon.
 
There is precedent for that suggestion, if you recall our earlier reports of the US Government-sponsored operation, by the FMC Corporation, of the "COED" indirect Coal conversion pilot plant in Princeton, NJ.
 
Carbonaceous residues from that operation, as we've documented, were sent all the way to Spain for liquefaction with Tetralin.
 
Note, though, as in: "One potential benefit with manufacturing these fuels in existing refineries is that 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", that Coal liquids, again as we've earlier documented, can be processed in conventional petroleum refineries, and, even if there are inefficiencies in this Penn State technology for making jet fuel from Coal, leftover liquid products can be utilized in the making of, as they report: "gasoline and ... diesel or fuel oil".


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