# US 2005/0109386 A1 · System and method for enhanced thermophotovoltaic generation

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- Number: US 2005/0109386 A1
- Document ID: US20050109386A1
- Status: Published application
- Kind: A1
- Application number: 10/984,261
- Filed: 2004-11-09
- Published: 2005-05-26
- Earliest claimed: 2003-11-10
- Assignees: Practical Technology, Inc.
- Inventors: Robert Marshall
- Web page: https://patentgrep.com/patent/US20050109386A1

## CPC

- G02B 1/005: {made of photonic crystals or photonic band gap materials (photonic band-gap structures or photonic lattices in integrated optics G02B6/1225; photonic band-gap structures or photonic lattices in optical fibres G02B6/02295)}
- H02S 10/30: Thermophotovoltaic systems (photovoltaic cells specially adapted for conversion or sensing of infrared [IR] radiation H10F10/00; thermoelectric devices H10N10/00)
- H02S 40/44: Means to utilise heat energy, e.g. hybrid systems producing warm water and electricity at the same time (directly associated with the PV cell or integrated with the PV cell H10F77/67)
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- H10F 77/122: comprising only Group IV materials
- H10F 77/124: comprising only Group III-V materials, e.g. GaAs
- H10F 77/311: {for photovoltaic cells}
- Y02E 10/50: Photovoltaic [PV] energy
- Y02E 10/60: Thermal-PV hybrids
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A system and method for lower cost, high efficiency, thermophotovoltaic distributed generation includes: an emitter, a photovoltaic cell, and transient electrical energy storage.

## Claims

### Claim 1

A system for thermoelectric power generation comprising:
a heated emitter;
a filter;
a photovoltaic cell;
an input thermal energy regulator; and
transient electric energy storage.

### Claim 2 (depends on 1)

The system of claim 1, where said heated emitter is a photonic crystal.

### Claim 3 (depends on 2)

The system of claim 2, where said photonic crystal possesses a 3D photonic bandgap.

### Claim 4 (depends on 2)

The system of claim 2, where the emission wavelengths are predominantly visible.

### Claim 5 (depends on 2)

The system of claim 2, where said photonic crystal possesses an inverse opal structure.

### Claim 6 (depends on 2)

The system of claim 2, where said photonic crystal is comprised of one material with a complex dielectric constant.

### Claim 7 (depends on 2)

The system of claim 2, where said photonic crystal contains: W, Mo, Cu, Au, Ag, Ge, Ge/Ni, Ge/W, or Ge/Ni/W.

### Claim 8 (depends on 2)

The system of claim 2, where the spectra of said emitted energy is tailored to a Si or GaAs photovoltaic cell.

### Claim 9 (depends on 2)

The system of claim 2, where said transient energy storage includes a capacitor or ultracapacitor.

### Claim 10 (depends on 2)

The system of claim 2, where said filter is one of: a photonic crystal layer with a different photonic bandgap than the photonic bandgap of said emitter, attached to said emitter; a photonic crystal with a different photonic bandgap than the photonic bandgap of said emitter, thermally isolated from said emitter; quantum dot; or phosphor.

### Claim 11 (depends on 2)

The system of claim 2, where said input thermal energy regulator consists of: an iris is interposed between said emitter and said photovoltaic cell; and/or a variable input fuel flow control valve.

### Claim 12 (depends on 11)

The system of claim 11, where said iris is perforated such to maintain an approximately uniform optical density.

### Claim 13 (depends on 11)

The system of claim 11, where said iris is momentarily opened or closed, the resultant change in photovoltaic output is monitored, and input thermal energy is adjusted to operate closer to the maximum power point of said photovoltaic cell.

### Claim 14 (depends on 11)

The system of claim 11, where said iris is adjusted by a load manager in anticipation of a load step.

### Claim 15 (depends on 2)

The system of claim 2, where a heat source is one or more of: solar, natural gas, propane, kerosene, diesel, coal, animal or vegetable oil, alcohol, geothermal, biologically contaminated fuel, cross linked fuel, fractionated fuel, water contaminated fuel, or waste process heat.

### Claim 16 (depends on 15)

The system of claim 15, where a burner also includes a recuperator and/or CCHP ports.

### Claim 17 (depends on 15)

The system of claim 15, where insolation is collected and converted to heat with a parabolic trough collector.

### Claim 18 (depends on 15)

The system of claim 15, where the temperature of said heat source is elevated with a heat pump.

### Claim 19 (depends on 18)

The system of claim 18, where said heat pump includes a photonic band gap emitter.

### Claim 20 (depends on 15)

The system of claim 15, where heat is stored for seasonal variations.

### Claim 21 (depends on 2)

The system of claim 2, where any block, group of blocks, input or output in the system is duplicated and connected for redundancy.

### Claim 22 (depends on 21)

The system of claim 21, where said system is in an environmentally hardened location, excluding a heat source.

### Claim 23

A means for thermophotovoltaic power conversion comprising:
a thermal input means;
a thermally stimulated photonic crystal optical emitter;
a photovoltaic cell; and
a means for providing a low impedance electric output.

### Claim 24 (depends on 23)

The system of claim 23, where said emitter comprises a photonic crystal with a 3D photonic band gap.

### Claim 25 (depends on 24)

The system of claim 24, where one material possesses a complex dielectric constant.

### Claim 26 (depends on 24)

The system of claim 24, where said photonic crystal has an inverse opal structure.

### Claim 27 (depends on 23)

The system of claim 23, where said means of providing a low impedance electric output includes an ultracapacitor.

### Claim 28 (depends on 23)

The system of claim 23, where a filter means improves the spectral matching of said emitter to said photovoltaic cell.

### Claim 29 (depends on 23)

The system of claim 23, including a means to vary the intensity of the incident energy on the photovoltaic cell such that said photovoltaic cell is operating at its maximum power point.

### Claim 30 (depends on 29)

The system of claim 29, including a means to determine said maximum power point by momentarily reducing and/or increasing the incident energy intensity on said photovoltaic cell and monitoring the resultant change in efficiency of said photovoltaic cell while said means for providing a low impedance system electric output prevents any deviation in system electric output.

### Claim 31 (depends on 29)

The system of claim 29, including a means to determine said maximum power point by momentarily reducing and/or increasing electric load on said photovoltaic cell and monitoring the resultant change in efficiency of said photovoltaic cell while said means for providing a low impedance system electric output prevents any deviation in system electric output.

### Claim 32 (depends on 29)

The system of claim 29, including a lookup table to determine said maximum power point.

### Claim 33 (depends on 32)

The system of claim 32, including a learning means to update said lookup table with more accurate values.

### Claim 34 (depends on 23)

The system of claim 23, where the means of thermal input includes a burner, catalytic converter, and/or recuperator.

### Claim 35 (depends on 23)

The system of claim 23, where the thermal input means includes waste heat generated by another process.

### Claim 36 (depends on 23)

The system of claim 23, where the means of thermal input includes a parabolic trough solar concentrator.

### Claim 37 (depends on 23)

The system of claim 23, including a means to store collected energy as heat.

### Claim 38 (depends on 23)

The system of claim 23, where the temperature of the thermal input is increased with a heat pump.

### Claim 39

A method of thermophotovoltaic power conversion including:
applying thermal energy;
thermally stimulating a photonic crystal to emit optical radiation;
converting said optical radiation to electric energy utilizing a photovoltaic cell;
adjusting incident energy on said photovoltaic cell for optimum efficiency; and
providing a low impedance output.

### Claim 40 (depends on 39)

The method of claim 39, where said photonic crystal exhibits a full 3D photonic bandgap.

### Claim 41 (depends on 40)

The method of claim 40, where said photonic crystal has a Lincoln log structure.

### Claim 42 (depends on 39)

The method of claim 39, where said photonic crystal contains one material with a complex dielectric constant.

### Claim 43 (depends on 39)

The method of claim 39, where said photonic crystal has dominant visible emissions.

### Claim 44 (depends on 39)

The method of claim 39, including further spectral shaping to match the optical spectra of said optical radiation to the highest photovoltaic conversion efficiency.

### Claim 45 (depends on 39)

The method of claim 39, where the incident energy on said photovoltaic cell is adjusted to the maximum power point of said photovoltaic cell.

### Claim 46 (depends on 45)

The method of claim 45, utilizing an iris.

### Claim 47 (depends on 39)

The method of claim 39, where the input to output power ratio of said photovoltaic cell is measured, a transient shift in input power is applied, the input to output power ratio is measured again, and the input power is adjusted to increase the input to output power ratio.

### Claim 48 (depends on 39)

The method of claim 39, where a capacitor provides said low impedance output.

### Claim 49 (depends on 39)

The method of claim 39, where said thermal energy is from a solar and/or fossil fuel and/or bio fuel and/or waste process heat source.