CLed from last thread:
Trump mentioned coal and the military earlier. He can’t build a coal-fired fighter plane (though they may spend billions trying) but there were some important applications in the past. Maybe he wants to revive them:

French cruiser Marseillaise underway, ca. 1903. Note that only 3 of the 4 boiler sets are working.

…..
HMS Jupiter, builder’s speed trial, 1897.