Anybody have experience with Sterno and related products? How much heat to they give off? I'm looking for something to give a little heat when I go winter camping with a fire ban. Obviously these aren't going to be like a campfire but how much heat do they give? If I set 4 cans on a table and sat next to it would I be able to feel the heat or are they basically just candles?
Could I also use them indoors as an emergency heat source during a power outage? My new apartment has shit insulation and if the power goes out it would probably drop to the 50s within a few hours. Could I light a few of these in my room to raise the temp a bit?

Also pic-related specify that they're good for s'mores. What's special about them? Why couldn't I use any of the other canned heat to cook s'mores?