moreshots wrote:So for infrared you can use electric or Propane?
Yes. Infrared is "light" emitted by hot bodies (your body is emitting right now 'light'). It is made up of the same stuff as radio waves or visible light (electromagnetic radiation). Usually people confuse long wave and short wave infrared. Short wave infrared behaves very similar to visible light so like in security cameras, you use a source and it bounces off from people. Long wave infrared is absorbed by bodies depending on their outer layer reflectivity to this wavelength (beans would absorbed it very well). For example, glass reflects long wave infrared but passes through visible light.
So if you heat up a piece of iron (or any other object), then it emits more long wave radiation (the type you want for roasting beans) which would be absorbed by the beans. Whether the heat source is electricity or gas, it does not matter in terms of emitting radiation. The only thing that matters is its temperature and its outer surface coat (emissivity).
Propane has the advantage that it heats up the air a lot, but that is not radiation. It is convection (a form of conduction).