[jdhwosnhw]

Useful, extractable energy comes from a temperature differential, not just temperature itself. Once your system is at temperature equilibrium, you cant extract energy anymore and must shed that temperature as heat

[dzhiurgis]

Enter https://en.wikipedia.org/wiki/Thermophotovoltaic_energy_conv...

[jdhwosnhw]

This still relies on a heat differential, as described in the Details section of your linked article: https://en.wikipedia.org/wiki/Thermophotovoltaic_energy_conv...