As part of their recently introduced Peltier device range, Thermaco limited also have available Thermo-Electric Generators (TEG’s). These devices can be used to convert existing differential temperatures in a given system, to actually generate electrical energy.
Normally you would use Peltier devices to create a temperature differential across 2 adjacent surfaces by using electrical energy. Typical example a picnic cool box which plugs into the car cigarette lighter. However, with a TEG the reverse is possible, using a temperature differential which already exists within a system it is possible to generate some electrical energy “for free” which can be utilised or could potentially be stored for future use in a battery.
Applications already utilising this technology include https://en.wikipedia.org/wiki/Thermoelectric_generator but clearly many more exist waiting for Design Engineers to unlock this potential.