That's what I was wondering. If any system creates heat, it's generally energy lost to that system, unless that heat energy can be converted to something else. Heat energy must be one of the most inefficient forms, in any localized sense.
What percentage or proportion of the total energy in the Earth-Moon system would be heat energy? I imagine it would have to be tiny. Can it be computed from the displacement of the Moon's movement away from the Earth? Lay questions, so please excuse if I'm wildly off track.