"Coal-Derived Fuel’s Advantages
Coal-derived liquid fuels are zero-sulfur paraffinic hydrocarbons that are similar to diesel. Because of its paraffinic nature, coal-derived diesel has a very high cetane number (about 75) compared to petroleum diesel (about 45). A high cetane number is necessary for efficient operation in diesel engines. The high paraffin content and low (less than 2% by volume) aromatic content also reduces particulate emissions. A test comparing coal-derived diesel with petroleum diesel on a 6.5-liter diesel engine for tactical vehicle applications showed that hydrocarbon emissions can be reduced by almost 50% compared to petroleum diesel. Carbon monoxide emissions were reduced by 50% and particulates by about 30%.
A potential approach to reducing CO2 emissions is to blend biomass with the coal feedstock. By doing so, the CO2 produced by the biomass fraction during production of the coal-derived fuel offsets the CO2 that was used up by the biomass during its growth phase by photosynthesis. Unfortunately, the logic cannot be extrapolated to a 100% biomass feed because of its low energy density and high moisture content (in comparison with coal) that leads to excessively high production and processing costs.
A recent study showed that by blending 15% to 30% biomass (by weight) with coal, the associated emissions can be 10% to 20% lower than the petroleum-derived fuel baseline.
In addition to environmental benefits, coal-derived liquid fuels have a high degree of thermal stability, which provides enhanced system performance for military aircraft. The DOD’s use of coal-derived liquid fuels could build public confidence and facilitate the introduction of such fuels into the private sector vehicle fleet."
We interrupt the excerpt so that we can emphasize the concluding paragraph:
"Overall, converting coal to liquid fuels is one element of an integrated approach that is needed to address fuel security. At least in the near term, it could bring a higher level of stability to world oil prices and to the global economy. Over the long term, it could serve as insurance for the U.S. (or any other oil-importing nation) against artificial or unwarranted price hikes from oil-producing countries."
It's difficult to state the benefits of coal conversion much better than that, except to offer the reminder that coal-to-liquid conversion technologies can be adapted to accept additional, renewable and CO2-recycling, biologically-based feed stocks, and be integrated with Sabatier-type processors for the direct capture and conversion of CO2 into even more hydrocarbon fuels and chemical manufacturing raw materials.
Peter N. Kuznetsov, Jan Bimer, Piotr D. Salbut, Evgeny D. Korniyets, Ludmila I. Kuznetsova and Colin E. Snape
Institute of Chemistry and Chemico-Metallurgical Processes, 42 K. Marx Str., Krasnoyarsk 660049, Russia
Institute of Organic Chemistry, 44 Kasprzaka Str., Warszawa 01-224, Poland
University of Strathclyde, Thomas Graham Building, 295 Cathedral Str., Glasgow G1 1XL, UK
Abstract
Kansk-Achinsk brown coal hydrogenation and swelling in tetralin, in low molecular alcohols, in other solvents and in binary mixtures were studied. Tetralin was found to be the most effective liquefaction solvent, but methanol and ethanol were the active ones in coal swelling. Synergistic effects were observed when the mixtures of tetralin and methanol or ethanol were used for liquefaction and swelling. The effect of binary solvents was shown to be due to the ability of alcohol components to cause brown coal to swell improving the availability of the fragments of coal matter for the reactive hydrogen donor tetralin molecules."
First, perhaps needless to say, Methanol, too, can be manufactured from coal. And, it can also, like Ethanol, but through a different process, be manufactured from biological raw materials, primarily cellulose.
And, note especially the statement: "Synergistic effects were observed when the mixtures of tetralin and methanol or ethanol were used for liquefaction and swelling."
Though not directly stated, we suspect the alcohols provide additional Hydrogen, beyond that supplied by the Tetralin, for the hydrogenation of the coal's carbon into liquid hydrocarbons.
In any case, the use of bio-derived alcohol both enhances the conversion of coal into liquid fuels and chemicals, and, provides a productive route for the recycling of atmospheric Carbon Dioxide.
It's about time we started taking advantage of this synergy to help supply our needs for energy, isn't it?
"(Agrawal reports) ' Power for the electrolysis would be provided by carbon-free energy sources, such as solar, wind or nuclear power. And, unlike conventional methods of producing liquid fuels from plant matter and coal, H2CAR would not emit carbon dioxide into the atmosphere.
The goal is to accomplish the complete transformation of every carbon atom in the feedstock to liquid fuel by supplementing the conversion process with hydrogen from a carbon-free energy source,' Agrawal said.
The process also offers potential advantages over producing liquid fuels from coal using conventional methods, which emit carbon dioxide. Because H2CAR would not emit this additional carbon dioxide, the process would eliminate the need for proposed carbon dioxide sequestering.
'The tremendous convenience provided by the existing infrastructure for delivering and storing today's fuels is a huge deterrent to introducing technologies that use only batteries or hydrogen alone,' Agrawal said. 'A major advantage of our process is that it would enable us to use the current infrastructure and internal combustion engine technology.' "
We'll emphasize one final point, which we have made before: As noted in the excerpt's final paragraph, converting coal and biomass into liquid fuels would vastly reduce the need for the hugely-expensive infrastructure and national vehicle fleet adaptations that would be necessary to accommodate more radical transportation concepts, such as electric and hydrogen-powered vehicles. That, of course, is in addition to recycling and forestalling the emission of CO2; and, to keeping the all the miners and farmers represented on West Virginia's state seal gainfully employed