Dtape, I emphasized the size because the dog mushers aren't carrying all of the fuel they are using, so the fact that alcohol has a lower energy per volume than white gas isn't as important-they just dump in as much as they need. I saw a photo of the Heet bottles stacked up in boxes at one of the rest stops.

The issue with alcohol in cold weather isn't that it won't burn (depending on the stove design), but that per volume, white gas is more efficient. You can get almost anything to work under any conditions if you try hard enough. The question is whether or not it's worth it.