Thermal energy harvesting using an electrostatic generator

Electrostatic generators have been conventionally used to harvest energy from ambient vibrations. The mechanical vibrations alter the gap between the electrodes or the overlapping area of a capacitor without a solid or liquid dielectric to change its capacitance. Despite their high power density, such generators have not been used - and are not intended - to harvest thermal energy. In this paper we have closed this gap and present an electrostatic generator in combination with a micro heat engine. This electrostatic energy harvester utilizes a capacitor with a ceramic dielectric, harvesting via the temperature dependence of its dielectric constant instead of using a mechanical dislocation of its capacitor plates. This system generates 40.4 μW of electrical power from a spatial thermal gradient of 85 K.