[@KiritoAsuna]not neccisarily. They might be able to produce energy in the physical realm but that doesn't mean they are consistent of energy

Edit: also baring in mind I'm allowed to dictate the physics of this world or the metaphysics. Whatever we may be dealing in XD the spirt world exists tangential to the mortal one. I haven't detailed what ghosts are made up of. Or where they go. And I've done that on purpose