I have read that the earth's internal heat is attributed to radioactive decay and residual heat from the Earth's formation. This feels intuitively wrong, or to be more specific, inadequate, to me. The, admittedly casual, reading I have done does not even mention what I would see as a significant input to the heat of the Earth. That is tidal friction. Not the oceanic tides but the tides within the core of the earth. The Earth moon system revolves around a barycenter beneath the Earths crust. The earth itself revolves on its central axis. These are different rotational motions, they have to generate stress and continuous flexing of the Earth's rock. Such flexing has to generate heat. Does anyone know how much heat? Or rather does anyone know how we might calculate how much heat is generated within the Earth by tidal stress?