The thing about bottles is that they're cheap, multi-purpose, very specific, don't have cords, pose no fire / tripping / electrocution risk, can be moved about, etc., etc.
A highly effective low-tech solution.
Yes, the efficiency of heating the water in the first place may vary, though that's energy that's almost certainly delivered to your residence space, so in that regard it's pretty much a wash.
A highly effective low-tech solution.
Yes, the efficiency of heating the water in the first place may vary, though that's energy that's almost certainly delivered to your residence space, so in that regard it's pretty much a wash.