I burned coal for about 3 years. Hated it. Especially on those cold Maine mornings when the air was very still, clear, cold and STINKY! The fumes are very acidic and burned our lungs. Basically runined the outdoor experience until the wind began.

Then there is the ash. Toxic. Nasty stuff, expecially in quantity. Made a good driveway for a few years until we saw what it was doing to the surrounding plants. Finally had it all dug out and disposed of it in a commercial toxic landfill (after some sort of proce$$ing).

Not to mention the dust. I thought burning wood was dirty. Coal dust is very difficult to remove from cloth and can be very fine, getting into everything. Also very acidic. Saw damage to circuit boards, photographs and other acid sensitive items.

This was the best coal we could obtain from the local chain of a large coal vendor.

Just my experience. ....Nomad.

Yes coal is nasty dirty stuff to store and handle and it does produce unpleasant fumes when burnt, and the ash is slightly toxic.
The smokeless coal that I suggested earlier is a bit better than natural coal, but still not pleasant.

I would favour burning wood normally but keeping a reserve of coal for emergencies. If in some future emergency, you would otherwise freeze to death, then dirt and smoke from coal will be of little consequence.

This was my thinking. Seems like a good item to have around for emergency heat, or prepping for teotwawki. Having a 5 to 10 year reliable fuel source when the grid goes down seems like an appropriate hedge, even if it may not be the most desirable materials. Loading coal from the bunker to the hopper and emptying the ash can seems less taxing than bucking firewood. I reckon any convenience I can buy for myself now would be well appreciated by me later when the bubble goes up.

It's important to note that the chemical properties of coal vary significantly from region to region. It is a geological mineral influenced by the conditions of its formation.

In eastern Canada (and I assume the broad area of the USA that is geologically contiguous) the coal is very high in sulphur, making it pretty nasty stuff when burned in volume. The treaties dealing with the acid rain that affected lakes on both sides of the border were, to a substantial degree, related to coal burning. (The granite underpinning, already naturally acidic, did nothing to temper the effects.)

In western Canada, in my general area at least, the coal is low in sulphur. The underlying rock of the basin is limestone, tending toward basic, providing some buffering of acidic effects. (The concerns over super-fine particulate matter and other emissions are leading to a slow phase-out in the power generation industry; it's become an air quality issue. But this does not affect modest use in non-urban areas.)

As for Alaska? I'm curious as to the general chemistry.

In storing coal, it may be wise to remember that coal is subject to spontaneous combustion. I think there was a thread several years ago where this was discussed.

Unlikely to be a problem for amounts likely for domestic use, but yes, still take care.

Coal when exposed to the air very slowly reacts with oxygen from the air to produce carbon dioxide and heat. Under most conditions this heat is removed by normal air circulation and no undue temperature rise is produced.
In the case of a sufficiently large coal pile the heat can not be removed and the interior of the pile becomes hotter, thereby accelerating the reaction and producing more heat and eventually fire.
When the fire is confined to the interior of the coal pile it burns very slowly due to the limited air supply and may not become obvious until the pile is disturbed. Exposure of the very hot inside of a slowly burning coal pile to fresh air may result in a fierce fire.
Risk factors that tend to promote spontaneous combustion include
Very large coal piles
High ambient temperatures
Coal dust or very small coal in the pile
Damp.
Left undisturbed for a long time.

If a coal pile becomes unduly heated within, but is not actually burning, then the coal should be spread out over a large area to cool it. A mechanical excavator or similar machine will probably be needed. Fire fighting equipment should be to hand.

For safe storage of a few tons up to a few dozen tons, I would proceed as follows.

if the coal was purchased in small bags on pallets store it thus, but do not stack the pallets atop each other and allow a free air space on every side of every pallet.

If the coal came in one ton bags, keep it thus but not stacked and with a free air space on each side of each bag.

For small bags stacked by yourself, stack in such a way as to leave plenty of air spaces within the stacks.

For coal tipped loose, pile it as convenient but avoid more than 5 tons in one pile.

Getting ready for an interruption in the normal energy supplies, I would also put a lot of reliance on wind and solar, especially with coming improvements in battery storage technology. I was dinking around last week with a solar oven, and I actually made tea and baked biscuits on my first tries. Not so great for space heating, but those photons and electrons are easier to move than lumps of coal. On the other hand, Xmas is coming and the lumps of coal may come in handy.

Why?

if you do a search, you can see pallets of coal stacked 2 high,
Truck loads of 20-24 tons commonly stored in a pile, or in a truck sized bin....

Absolutely, coal is often transported or stored SHORT term in ways other than I suggest.
Road vehicles commonly carry up to 40 tons, rail vehicles up to 100 tons, and more than that is routinely tipped or dumped in one pile awaiting use or transfer.

If however you are storing coal on your property perhaps for decades, then I suggest being a great deal more cautious than a large industrial coal user with a rapid turnover.

so you're making stuff up? I like to do that too

One problem with lots of air spaces, is you're losing calories ... 2000-5000 ton test piles

its hard to find info, anyone buying coal need to talk to someone in the industry