The quality may depend on the location. Apparently Alaskan coal ranges from anthracite (great stove coal) to sub-bituminous or thermal coal (scurvy stuff for stoves unless they use a forced draft). Reference: http://pubs.usgs.gov/dds/dds-077/dds77text.html#heading154533232 .

Stored coal needs to be dried and kept as dry as possible, otherwise it will break down into dust over time, and that is really hard to make use of. Wet coal is problematic, obviously, because even if you can get it to burn, most of the heat energy goes up the flue as steam.

Storage location and method also has to account for coal's tendency to self-combust. I haven't had a problem storing it in closed pails in a shed, but power plants with coal piles exposed to the wind monitor them closely for evidence of combustion.

Then there's the challenge of a stove that will burn coal well. Wood stoves don't supply enough draft/oxygen, and the intense localized heat can cause serious damage. I imagine some sort of insert could be cobbled together in a pinch.

The bonus of a coal-fired stove is that the flue runs very cool and doesn't deposit creosote. And, if you use large lumps and know what you're doing, you can bank a fairly small stove to keep a cabin toasty all night. (A CO detector would be a good idea since heated coal produces oodles of it, and a partially blocked flue could lead to a very long sleep indeed.)