Apparently there has been an idea around for a while to use coal in diesel engines. The idea is to pulverise coal into fine particles and mix it with water to form a slurry and inject this into the compression chamber of a diesel engine where it would explode with the compressed air just like normal operation of a diesel (its said that Rudolf Diesel used coal in this way for the first tests of his engine but it was too unstable explosively destroying the engine and killing a bystander).
This idea is now being looked at again with the weekend edition of the Australian Financial Review (27/28th September) publishing a fairly lengthy article about a guy, originally with BHP, who is pursing developing this idea for stationary power. The article says it would have a number of advantages for stationary power including: being able to be turned off and on as needed unlike a coal fired, steam base load station, the units can be smaller i.e. 10 kW to 300 MW and located where needed so eliminating power transmission lines from remote sites to towns, cities and industrial sites. The idea is to stack up the engines, in modular form, to give the mount of power needed, unlike one giant coal fired boiler.
The article sets out environmental advantages that the configuration of such an engine for electricity generation could have because being able to be turned off and on as needed it could work with perceived variability in renewable generation, as gas turbines generators can, its more efficient than burning coal in a boiler, it perhaps uses less water than a boiler and the water in the slurry can also be recycled and according to the article transporting coal to various sites close to cities and industrial sites results in less emissions than than the need to make up for transmissions losses by producing more power. That last one I’d have to wait for a proper assessment. I also have questions on how much energy would be need to pulverise the coal down to very, very fine particles.
I don’t know much about the processes for capturing CO2 and other gases for sequestration after burning but I wonder whether this might easier from a tailpipe (i.e. the output of the engine) than from a chimney. The article mentions that an Australian company is seeking to build a demonstration plant. I did a quick (very) google and didn’t find much on this idea except a few pieces going back nearly 20 years.