That kills off a quanta of energy from whatever phonon mode gave the kick (which cools the LED), and the electron emits a photon when it relaxes back into the valence band. The LED is no longer in thermodynamic equilibrium with the surrounding environment, so heat flows into the LED.
Right now, most energy that becomes heat is considered wasted because of limited applications in turning that heat back into usable energy.
When did they say these things would be industrial scale again?