They can be powered with small generators though. Most are around about 1800 watts or less. I’ve actually use one to thaw out outside pipes. We have a property in the country and a deep well that would sometimes freeze where the pressure switch mounted. Another thing that works well for frozen pipes, but you must be careful, is a small propane bottle with a torch attached to the top. They’re also great for starting a fire - works much better than matches!
Mr. mm’s favorite way to start the charcoal for a cookout.