Patent ID: 7982360

Claim:
An apparatus for converting heat to electric energy, comprising: (a) a ferroelectric layer having a first surface and an opposite, second surface, wherein the ferroelectric layer is comprised of a ferroelectric material characterized with a phase transition temperature such that, when the material is in a ferroelectric phase spontaneous polarization is established in the unit cells of the ferroelectric, and the ferroelectric layer, upon poling, develops an overall net spontaneous polarization; and such that, as the temperature of the ferroelectric changes so that it traverses the transition temperature, the material enters a paraelectric or antiferroelectric phase wherein the ferroelectric layer has negligible or no overall net spontaneous polarization; (b) a pair of electrodes respectively positioned on the first surface and the second surface of the ferroelectric layer, wherein the pair of electrodes is formed of a thermally and electrically conductive material; (c) one or more heat exchangers positioned in relation to the ferroelectric layer for alternately removing and inputting heat by convection, conduction, or radiation from and into the ferroelectric layer, so as to alternately cool the ferroelectric layer at a first temperature T L that is lower than the phase transition temperature, and alternately heat the ferroelectric layer at a second temperature T H that is higher than the phase transition temperature, so that the ferroelectric material of the ferroelectric layer thereby undergoes alternating phase transitions between the ferroelectric phase and the paraelectric or antiferroelectric phase; (d) a voltage source positioned in relation to the ferroelectric layer and the pair of electrodes for applying a DC voltage and a resulting electric field for poling the ferroelectric layer in, or during the transition to, the ferroelectric phase, an external field not otherwise being applied to the ferroelectric layer, wherein the ferroelectric layer, the pair of electrodes, and the one or more heat exchangers are configured such that when the ferroelectric material of the ferroelectric layer is in the ferroelectric phase, electrically-opposite screening charges are respectively generated on the pair of electrodes, and when the ferroelectric material of the ferroelectric layer transitions into the paraelectric or antiferroelectric phase, the generated electrically-opposite screening charges on the pair of electrodes are discharged therefrom as electric energy; and (e) a control circuit connecting the pair of electrodes to a load while the one or more heat exchangers are heating or cooling the ferroelectric material such that the generated screening charges on the pair of electrodes are discharged therefrom as electrical energy during the transition of the ferroelectric material from the ferroelectric phase to the paraelectric or antiferroelectric phase.