Compare this to a Phonovoltaic cell, which is similar to a photovoltaic cell, but instead of converting the energy of a photon into electricity, it converts the

Compare this to a Phonovoltaic cell, which is similar to a photovoltaic cell, but instead of converting the energy of a photon into electricity, it converts the energy of phonons - packets of heat vibrations in solids [1]. Unfortunately, no one has as yet found a material with the right combination of thermodynamic properties to realize such devices. Otherwise, you could stick these to any source of high temperature heat and get electricity out. [1] https://en.wikipedia.org/wiki/Phonovoltaic https://en.wikipedia.org/wiki/Phonovoltaic