Coal was surpassed by oil much earlier than that. By WWI for the most part. But there were special circumstances through the years. I don't know about the Badger, but there are others ships as well as a Florida company that is trying to develop an efficient, powdered coal engine now
Cyclone Power Technologies - Cyclone Engine
Also, in 1940, Great Britain ordered 60 coal fired steam Liberty Ships because of more secure local access to coal supplies.
What follows is from articles about coal fired steam ships built in the early 1980's in response to special local circumstances and the 1973 energy crisis and consequent oil price rise.
———————
River Embley marks the end of an era (May 2012)
The withdrawal from service of River Embley this week marks the closing of a unique chapter in bulk shipping.
River Embley, and her sister ship River Boyne, are the only commercially-trading coal-fired bulk carriers in the world and have spent their 30-odd years as floating bauxite conveyors between Weipa and Gladstone, Queensland.
The pair was half of an innovative quartet of built for the Australian coastal bauxite trade in the early 1980’s. The other two vessels, Endeavour River and Fitzroy River (ex TNT Carpentaria and TNT Capricornia) were built in Italy for TNT Bulkships while River Embley and River Boyne were built at Mitsubishi’s Nagasaki shipyard for ANL.
At the time of their design, fuel oil bunkers were at historicaly high levels and Queensland had plentiful, cheap steaming coal. Though built at different Yards and to different designs, the principles are the same. Coal is loaded into gravity-fed hoppers adjacent to the accommodation. Automatic coal handling systems deliver the coal on to moving conveyor grates running through the boilers driving steam turbines and a single propeller.
Despite running on a solid fuel, the vessels were classed UMS (Unmanned Machinery Space) meaning they would run automated with day-working Engineers. At normal sea speed, the ships consumed between 180 and 240 tonnes of coal a day. Increasing maintenance costs, and their replacement by more standard Post-Panamax bulk carriers, means their time has come and River Embley will sail from Gladstone next week to Singapore and new Owners.
The Antipodean Mariner
Antipodean Mariner: River Embley marks the end of an era
From 1981:
And in the United States, where no coal-powered ship has been built since 1953, New England Electric has contracted with General Dynamics Corporation to construct a $60-million coal-fired vessel at its Quincy, Mass., Shipyard. The ship will carry 2.2 million tons of coal annually along the Eastern seaboard, using about 1 percent of the cargo for its own power.
Coal-powered ships: a nostalgic way to cut costs - CSMonitor.com