[BobaFloutist]

The sun is arguably ultimately responsible for geothermal. Even if geothermal is part of the closed system, it's still functionally perpetual motion for our purposes. The main argument I'm making is that perpetual motion* is, for all practical purposes, possible, as long as you're willing to be specific, and you're unconcerned with the heat death of the universe (none of us should be concerned with the heat death of the universe).