We've many times documented the extensive Coal liquefaction technologies that had been developed, over the course of multiple decades, by the old US Bureau of Mines outpost in Pittsburgh, PA; a facility that is now a component of the US Department of Energy.
We have also, from various sources, documented that different kinds of energy, including Solar light and heat, microwaves; and, electricity, as generated from any economical source, can be used to facilitate the conversion of Coal, and especially of Coal-Water and/or Coal-Oil mixtures, or "slurries", into more versatile hydrocarbons.
Herein, from Pittsburgh, is a new one.
Most of us have heard of - without really having any clue as to what it actually means - "ultrasound".
Without going into details, it is, simply, high-energy and high-frequency sound waves beyond our range of hearing. Think of a "silent" dog whistle, and you'll be in the ballpark.
In any case, "ultrasound" isn't that hard to generate; and, herein, the US Bureau of Mines says that it can be used to facilitate the conversion of Coal into more versatile liquid hydrocarbons.
Comment follows excerpts, with one explanatory comment and link inserted, from the above link to:
"United States Patent 3,577,337 - Solvent Extraction of Coal
Date: May, 1971
Inventor: Theodore Kessler, et. al., Pittsburgh, PA
Assignee: The USA, as represented by the Secretary of the Interior
Abstract: Coal is extracted in quinoline by treatment of a coal-quinoline slurry with ultrasonic irradiation at ambient temperature. ... The solubilized fraction may be used for production of gasoline ..., etc.
This invention relates to solubilization or extraction of coal to form products that are low in both sulfur and ash content. These products may be used directly as fuels, e.g., in power plants, or they may be further processed into gasoline, chemicals ..., etc.
It has now been found, according to the process of the invention, that the use of quinoline as solvent, when exposed to ultrasonic radiation, results in an efficient and economical extraction of coal.
In the process of the present invention ... the extraction may be carried out at ambient temperature.
(And, the) economics of the process is thereby considerably improved as a result of the reduction or elimination of the required amount of thermal energy.
(Since the need for "thermal energy", i.e., heat, is reduced, we submit that the potentially concurrent generation of effluent Carbon Dioxide is also reduced, since no Carbon has to be combusted to provide such "thermal energy". Moreover, don't be distracted by the specification of "quinoline" as a Coal solvent. It is, in fact, one of the lesser-known primary Coal oils, or tars, that are rather easily producible. More concerning it can be learned via:
quinoline - definition of quinoline in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclope; which reveals that quinoline is "synthesized or obtained from coal tar".)
Quinoline has been found to be unique in exhibiting efficient extraction at ambient temperature.
According to the process of the invention, a slurry of the coal in quinoline is subjected to ultrasonic irradiation at ambient temperature. (The) invention is generally most effective with .. bituminous coals; however, other coals ... may be used.
Pure quinoline is not necessary for efficient extraction ... .
Ambient temperature, i.e., about 30 C, is generally optimum in the process of the invention.
Atmospheric pressure is satisfactory.
Inert gases may be used but generally show no advantage.
(Note, again: Low temperature and low pressure = lower cost. And, there is no need to add the expense of obtaining and utilizing purified "Inert gases".)
Claims: A process for extraction or solubilization of coal comprising a slurry of coal in quinoline and subjecting the coal-quinoline slurry to ultrasonic irradiation at a temperature of about 20 to 40 C."
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And, according to the now-USDOE, such Coal, thus slurried in the Coal oil, "quinoline", is dissolved by the action of "ultrasonic irradiation", and the resulting solution then "may be used for production of gasoline".
As a bonus, although not reflected in our excerpts, the full Disclosure also reveals how more of the needed quinoline Coal solvent can be generated as a by-product of such a low-energy, and thus lower-cost, process; one that converts "bituminous coals" via "an efficient and economical extraction" into such liquid "fuels (which) may be further processed into gasoline" and other "chemicals".