Storm-season advice that gets people hurt
Emergency heat at home: the Sterno CO problem nobody mentions
Every power cut brings the same suggestion: keep a few cans of canned heat in the cupboard. The peer-reviewed case report says be careful what you do with them.
Canned heat is sold as emergency cooking fuel and it works. The caution is about where it is burned. A published case report describes a student who lost consciousness working over three cans of burning Sterno in an enclosed space; carbon monoxide measured around the apparatus reached 1,000 to 3,000 ppm.
A kitchen in a blackout is an enclosed space
Windows shut against the weather, extractor fan dead, a family gathered around the one warm thing in the house. That is the case report's set-up.
If you must
Burn it near an open window, never in a bedroom, never overnight, and fit a battery carbon-monoxide alarm before the storm season, not during it.
The other option
A water-activated heat pack produces steam and no combustion product. It will hold a pan of food hot for about 45 minutes with the windows shut and the alarm silent.