My parents heat mostly with coal. They have a multi-fuel furnace that burns oil, wood or coal. One of these
Yukon Husky Wood Furnace . Since it's inside, there's no going out in rain/snow to tend it. A few shovels of coal (nut) holds it overnight. On days like today where it was quite warm during the day, it held a good 18 hours with no real tending. You can easily get the house too hot, if coal had been fed in this morning the house would have been pushing 80F all day.
How much they burn depends partly on the weather and also the quality of the coal as not all coal is created equally. The coal I ended up buying for them last fall didn't come from where they've preferred and was not good at all, even with the very mild winter I estimate they used between 1/4 to 1/3 more coal each week.
When the coal is good and the fire actively tended, they may burn 3-5 ton per winter along with about 1.5 cord of wood and a 1/4 tank of oil.
Where they buy the coal sometimes is determined by who has it when they need it. Since they are in the coal region near
Shamokin, Pennsylvania - Wikipedia, the free encyclopedia, they can get it straight from the breaker. Last weekend I picked up 1700lb with the pickup. My preference is using the Bri-Mar trailer since I can drag about 6000lb home at one time.
Storage is basically in three places. I put bin at one end of their property for bulk storage and can comfortably fit 3 ton in it. Drawback to that space is I cannot dump the trailer into it due to it being a low deck trailer. Shoveling coal is a workout.

They have another trailer, an old utility trailer, that isn't safe for road use and is parked next to the basement door for the winter. I modified it to have an expanded steel bed floor which allows any snow that accumulated on the coal to drain out once it melts and have a removable cover to keep it dry. Some coal does get lost though. I can keep about 4 - 5 weeks of coal in the trailer. I want the coal dry only because it means I'm not bringing water into their basement. Inside storage is a garden wagon which I roll outside weekly and fill with coal. That should hold slightly over a week but since this coal was crap, I supplemented it with a poly cart so my mother isn't stuck shoveling coal outside in the dark. When my dad was in good health, he did all of that so a larger indoor supply wasn't important. Coal cost is anywhere from $100 - $200 per ton, that's with me going and getting it.
Ashes are the by product of course. They have 3 metal trash cans which I take to another end of their property and dump on a pile. I'd like to find a use for them.