Oh it does - I know because I use a moka pot every morning on the small ring. Put your hands around it when it's on and see how much heat escapes! It's the same issue that afflicted steam engines - when the flame is heating something that is external to it, loads of heat just goes into the air. Also, moka pots aren't insulated - or at least mine isn't, so heat is lost that way. The electric ones are much more efficient. I'd imagine, but less use on a campsite (where ours also sees active service)