A TEG system is attached to a rotating shaft and generates electricity from radiant energy that is substantially radiatively transmitted through the atmosphere from a stationary source to the TEG system that is rotating with the shaft. The rotation of the shaft provides cooling to the TEG system, but not heat energy. The TEG system includes at least one TEG, each TEG equipped with an energy receiving and heat containment window and an energy conversion system in combination with controlled convection cooling enhanced by an airflow moving in response to the rotation of the rotating shaft. Individual TEGs having controlled convection cooling also are described.