I tried winter/snow hiking and camping, but it wasn't for me. I've dealt with snow and ice and an occasional winter-like storm of short duration in shoulder season at altitude, but I've never been whited out, snowed in, etc.

Would a tiny alcohol burner be worthwhile as a survival aid in an unplanned alpine winter bivouac, or is the heat output too low to be of much real help?

How much fuel, either white gas for, e.g., an MSR stove, or denatured alcohol for a Trangia or cat-can stove, do you estimate would be required to minimally heat a small survival shelter for, say, 12-24 hours?