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Researchers Exploring New Refinery-Based Coal-to-Liquids Pathways for Jet Fuel and Other Products

Researchers at Penn State University are investigating several coal-to-liquid processes that differ from traditional direct (Bergius) and indirect (Fischer-Tropsch) liquefaction. The new pathways could introduce coal-derived chemicals or coal into existing oil refinery operations for the production of end products including jet fuel, gasoline, diesel, heating oil and carbon anodes.

The primary focus of the work, which is funded by the Department of Energy, is the development of a coal-based replacement for conventional jet fuel. The coal-to-jet fuel work is in the pilot-plant stage, but along with the jet fuel, the processes produce other hydrocarbon products. For every eight barrels of a Jet A equivalent, the process produces a half barrel of fuel oil, one barrel of diesel and a half barrel of gasoline.

Pilot-scale testing indicates that a prototype fuel meets most of the current specifications for JP-8. Combustion tests in a turboshaft engine show emissions to be generally comparable to those from control experiments with JP-8.

The work focuses on three processes:

  1. Coal tar/refinery solvent blending and hydrotreatment to produce the various product fractions. This is the process demonstrated in the pilot plant.

  2. Co-coking of coal/refinery solvents. This process to produce jet fuel mixes raw, clean coal with decant oil—the liquid found at the bottom after catalytic cracking—and then co-cokes. The liquid from the coker is hydrotreated and fractionated to provide the desired products. This co-coking process aims to produce coke or carbon of much higher quality usable in manufacturing carbon anodes for a variety of uses. Fuel-grade coke, which is a standard fuel in the steel industry, sells for about $20 a ton.  The coke used in these anodes is a much higher value than fuel coke.

  3. Coal extraction using refinery solvents. This method uses light cycle oil to extract the liquid components of coal and then the liquid portion, without separation, travels on through the refinery hydrotreater. In initial bench testing, this method produced a 50% yield of liquids. When processed in a multistage reactor, 70% extraction took place. The researchers are continuing this work to reduce the amount of light cycle oil necessary, develop a method to separate liquids and solids, and scale up the process.

Our aim is to integrate the processes and products into existing refinery structures and streams. We need to be sure that these components fit into the refinery stream that they are close enough in composition to be mixed with the components coming from crude oil.

—Caroline E. Burgess-Clifford, Penn State Energy Institute

So far, the researchers, including Harold Schobert, professor of fuel sciences; Maria M. Escallon and Utaiporn Suryapraphadilok, graduate students; Gareth D. Mitchell, Omer Gul, Josefa M. Griffith and Parvana Gafarova, research associates, Energy Institute, characterize the gasoline and fuel oil as fitting within the standard crude oil refinery stream. The diesel fuel is different from standard diesel fuel.

Other participants in this project tested the products in real units, including Andre Boehman, professor of fuel science and his group who tested the gasoline and diesel in engines; Bruce Miller, senior research associate and his group who tested the fuel oil in a pilot scale boiler; and Chunshan Song, director of the Energy Institute and professor of fuel science and his group who did related catalyst research.

The produced diesel can be blended with the petroleum diesel without changing the fuel properties significantly. It has not been shown to be bad or have bad effects, it is just different. We are also examining the produced jet fuel to see if it could be used as a diesel fuel, as the jet fuel has undergone extensively more processing than the other products. So far the process has produced really good carbon, but it contains too many residual minerals for anode use. The liquid component does include jet fuel, but the liquid products are very heavy in fuel oil.

The researchers presented their work in a series of papers at the American Chemical Society meeting in Boston. Future work will strive to reduce impurities in the solid carbon product. Researchers will also investigate either fractionating the fuel oil component or improving the liquid yield.



Alex Kovnat

The problem with coal-to-liquids technology is, you're taking carbon that's been buried since time immemorial, burning it, and adding the resulting CO2 to our atmosphere.

Every day as I go about my life, I see biomass everywhere - trees, shrubs, weeds. Would that we could find suitable ways to harvest and use it.


A recent New Scientist article says we're better off planting trees for offsets and using oil rather than first generation biofuels. They estimate 2-9 times the fossil CO2 emissions based on current agricultural methods.

There's no information about the CO2 intensity of these processes in this post, so I can't hazard a guess if this is a good thing or a bad thing. Or if it's better or worse than those first gen biofuels.


This reminds me of the world of the Sci Fi novel "Dunes".
As Baron Vladimir Harkonnen said "the Spice must flow"

Coke Machine


You wrote:

"The problem with coal-to-liquids technology is, you're taking carbon that's been buried since time immemorial, burning it, and adding the resulting CO2 to our atmosphere."

How is this any different from petroleum?

Alex Kovnat

Coke Machine:

Refining petroleum into useful fuels and then burning said fuels in cars, airplanes, etc. obviously does contribute to buildup of atmospheric CO2 but from stories I've heard, coal is worse.

Essentially, coal is pure carbon (=cokes) plus hydrocarbons. In coal-to-liquid technologies, you do C + H2O --> hydrocarbon + CO2.

wether you use coal-carbon or charcoal-carbon, you have the same result.
So if make charcoal out of biomass, you can just throw the charcoal in your coal-to-liquid refinery, and you make liquid fuels.

making charcoal out of wood is very simple (they did it in the bronze age), actually it is exactly the same process as we do to make cokes out of coal. (the gases released in the carbonisation process can be used as heating gass or to drive a turbine)

For the moment, coal is cheaper than charcoal. So they use coal. But once the refining-technology is mature, there will be absolutely no technical obstacle to use biomass instead of coal, only financial. Carbon taxes or mass-produced biomass may change that


In view of the recent coal mine disasters, you have to ask who is going to mine the coal that is gong to be harder and harder to get for the next 100 years.

I look at biomass as the planet's solar collector. We use the current account energy absorbed now and save the prehistoric savings account for later. You never know when you might need it and if it has been used up, you are in a bind.

Paul Dietz

In view of the recent coal mine disasters, you have to ask who is going to mine the coal that is gong to be harder and harder to get for the next 100 years.

In-situ gasification, followed by cleanup and conversion of the syngas to useful fuels.



Robots will mine the coal, it called telemining. Also direct gasification also works:


Did it occur to anyone that all that evil carbon in coal and oil was once CO2 in the atmosphere? The earth has had C02 levels 20 times the current amount and the world did not end. Why do you think the geologic epoch when all the coal and oil formed is names the carboniferous period? Get the facts from places other than the Internet and political hacks. Try your local Universities geology department for starters.

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