Currently (v0.98.0) there are only two buildings that can store Charcoal for the Zolarg civilization: The Mound (stores 2500 Charcoal) and the Smoldering Pit (stores 100 Charcoal).
While Charcoal isn't needed until very late into the game of a Zolarg colony, the building that actually stores the most/tile is a building you will most likely get rid of in your late mid-game to get enough colonists (and Antaura) for various other buildings. That being said, one Antanium Blast Furnace (the only building that needs Charcoal to build it) needs a whopping 25.000 Charcoal. This being said, you can try to fit 10 Mounds that only get you very few colonists on your map or fit the 250 Smoldering Pits that are needed to be able to build one Antanium Blast Furnace.
TL;DR Can we get some Charcoal Piles for Zolarg? Or storage in the Supply Piles/Quantum Supply Piles, Unholy Pit of Stuff/Unholy Tower of Stuff?
Iirc, bast said that that was a mistake on his part and that he is planning on fixing that in .99 along with the ehterbugs being unavailable. My understanding was that he had intended to add it to the storage mounds and pits, but just forgot along the way.
The storage for charcoal, software, and oil have been added to zolarg storage buildings in latest beta build of 0.9.9.