A pyroelectric can be repeatedly heated and cooled (analogously to a heat engine) to generate usable electrical power. An example of a  heat engine is the movement of the pistons in an internal combustion engine like that found in a gasoline powered automobile.
One group calculated that a pyroelectric in an Ericsson cycle could reach 50% of Carnot efficiency, while a different study found a material that could, in theory, reach 84-92% of Carnot efficiency (these efficiency values are for the pyroelectric itself, ignoring losses from heating and cooling the substrate, other heat-transfer losses, and all other losses elsewhere in the system).
Possible advantages of pyroelectric generators for generating electricity (as compared to the conventional heat engine plus electrical generator) include:
* Harvesting energy from waste-heat
* Potentially lower operating temperatures
* Less bulky equipment
* Fewer moving parts.
Although a few patents have been filed for such a device, such generators do not appear to be anywhere close to commercialization.