Various methods and apparatus for solar assisted fuel production

Abstract

Products from a solar assisted reverse-water-gas-shift reaction (RWGS) are used to create a liquid hydrocarbon fuel. Heliostats focus solar energy to heat carbon dioxide gas. A water splitter splits water into hydrogen molecules and oxygen molecules via the addition of the solar energy also directed from either the same array of heliostats via a beam splitter off a common receiving tower redirecting a portion of the electromagnetic spectrum, a heliostat field dedicated for the water splitter, or from its own parabolic trough. A chemical reactor mixes heated carbon dioxide gas with all or just a portion of the hydrogen molecules from the water splitter in a RWGS reaction to produce resultant carbon monoxide. A synthesis reactor uses any unconsumed hydrogen molecules and the resultant stabilized carbon monoxide molecules from the RWGS reaction in the hydrocarbon fuel synthesis process to create a liquid hydrocarbon fuel.

1 . An apparatus, comprising:
 a window, where a first solar receiver focuses solar energy thru the window to a solar-energy-to-gas-heat-exchanger to heat carbon dioxide gas via convection heating of the carbon dioxide gas from the heated solar-energy-to-gas-heat-exchanger;   a gas supply input to receive gases from a water splitter containing one or more electrolysis cells to split water molecules into hydrogen molecules and oxygen molecules via the solar energy directed at the one or more electrolysis cells from at least one of 1) the first solar receiver, 2) an array of heliostats separate from the first solar receiver and 3) a parabolic trough separate from the first solar receiver;   a chemical reactor chamber to mix the heated carbon dioxide gas with the hydrogen molecules from the water splitter in the form of gas in a reverse-water-gas-shift reaction to produce resultant carbon monoxide and water molecules as well as unconsumed carbon dioxide gas and hydrogen molecules;   a recuperator to pre-heat both the carbon dioxide gas and the hydrogen molecules from the water splitter using at least an energy of the resultant carbon monoxide exiting the chemical reactor chamber where the reverse-water-gas-shift reaction occurred; and   a gas supply output to supply at least the resultant carbon monoxide molecules and unconsumed hydrogen molecules from the reverse-water-gas-shift reaction to a hydrocarbon liquid fuel synthesis reactor to create a liquid hydrocarbon fuel.   
   
   
       2 . The apparatus of  claim 1 , wherein the water splitter further comprises:
 the parabolic trough contains a set of parabolic mirrors, where each mirror connects to a tracking actuator to rotate that mirror in both an azimuth axis and an elevation axis, where each parabolic mirror reflects sunlight upwards in a frame of the parabolic trough at a focal line of the parabolic trough onto an associated light receiver that contains tubes with a titanium based catalyst forming the one or more photoelectrolysis cells, wherein the light receiver and frame in the parabolic trough may be tilted at a slight upward angle to allow disassociated gases of hydrogen and oxygen from the water splitting process to naturally float upward and be collected/harvest for future use.   
   
   
       3 . The apparatus of  claim 2 , further comprising:
 a quenching unit to immediately cool at least a portion of exit gases from the chemical reactor chamber in which the reverse-water-gas-shift reaction occurs, in order to stabilize at least the carbon monoxide molecule in the exit gases, wherein the parabolic trough uses multiple mirrors, each mirror with a frame construction having two axis of rotation and the frame is coupled to the tracking actuator, and   an electronic controller coupled to the tracking actuator and feedback limit switches to control positioning of each mirror to concentrate the solar energy on the associated light receiver, wherein the parabolic trough is composed of multiple individual mirrors connected together to form the trough and a series of the associated light receivers are ganged together in a frame of the parabolic trough.   
   
   
       4 . The apparatus of  claim 2 , further comprising:
 a front surface of a reflective mirror portion of each mirror in the set of parabolic mirrors is formed by a reflective metal, wherein the unconsumed carbon dioxide gas and hydrogen molecules from the reverse-water-gas-shift reaction are also used in the recuperator to pre-heat both the carbon dioxide gas and the hydrogen molecules prior to entering the chemical reactor chamber.   
   
   
       5 . The apparatus of  claim 4 , further comprising:
 a polymer or acrylic coating on top of the front surface of the reflective metal mirror, which is optically transmissive in passing wavelength bands in an electromagnetic spectrum below infra red is on top of the front surface of the reflective mirror to maximize an amount of solar power being concentrated into the light receivers in a desired UV and visible light spectrum while limiting generation of waste heat, and the hydrogen splitting with the tubes with the titanium based catalyst in the light receiver occurs at 50-80 degrees Celsius and 30-50 sun concentration units.   
   
   
       6 . The apparatus of  claim 1 , wherein the gas supply output supplies a portion of the unconsumed carbon dioxide from the reverse-water-gas-shift reaction to the hydrocarbon liquid fuel synthesis reactor. 
   
   
       7 . The apparatus of  claim 1 , wherein the water splitter has one or more light receivers with tubes that use a titanium based catalyst forming the photoelectrolysis cells that receives UV rays and visible light from an array of heliostats splits the water into the hydrogen and oxygen molecules via the titanium based catalyst, where the titanium based catalyst absorbs both the UV rays and a portion of the visible light directed from the array of heliostats, and where the titanium based catalyst is in a shape to strain the catalyst to 1) pull apart its atoms or 2) even compress together its atoms in order to alter the material's electronic properties and allow the titanium based catalyst to absorb both wavelengths in the portion of the visible light and ultraviolet light spectrum. 
   
   
       8 . The apparatus of  claim 7 , wherein the titanium based catalyst consists of titanium oxide nanotubes in a strained shaped ripple pattern coated with a tungsten oxide to enhance the visible spectrum absorption of the titanium dioxide nanotube array, as well as their solar-spectrum induced photocurrents. 
   
   
       9 . The apparatus of  claim 7 , wherein the water splitter may be a tower mounted device that contains the one or more photoelectrolysis cells, where each cell has a clear tube filled with an aqueous electrolyte solution that reacts with the titanium. 
   
   
       10 . The apparatus of  claim 1 , wherein the electrolysis cells are photoelectrolysis cells that dissociate water and produce the hydrogen molecules in the form of gas from an aqueous solution when exposed to the solar energy, and the photoelectrolysis cell employs an electrode made of a titanium-based element or compound with a stress-induced band-gap that is shifted and broadened to absorb both wavelengths in a portion of the visible light and the ultraviolet light spectrum. 
   
   
       11 . The apparatus of  claim 10 , wherein the electrode contains a substrate that has surface ripples with a sub-visible-light-wavelength spatial period that causes stress in the titanium-based element or compound on the substrate in the form of a thin film and thereby shifts the bandgap of the titanium based element or compound to support spontaneous photoelectrolysis of the water in visible light. 
   
   
       12 . The apparatus of  claim 1 , wherein the water splitter contains one or more high-temperature electrolysis cells for water electrolysis that decompose the water into the oxygen and hydrogen molecules in the form of gas due to an electric current being passed through the water with most of the energy causing the high temperature above 280 degrees Celsius supplied as heat from the solar energy from a separate array of heliostats. 
   
   
       13 . The apparatus of  claim 1 , further comprising:
 an optical filter to pass a portion of the electromagnetic spectrum including the visible light and UV ray range from the heliostats into the electrolysis cells in the water splitter at around 20-50 sun concentration units, wherein the first solar receiver is an array of heliostats that focuses the solar energy from their mirrors onto a dish on a first tower portion of the water splitter which is coated with the optical filter.   
   
   
       14 . The apparatus of  claim 10 , further comprising:
 one or more solar photovoltaic cells that receive solar energy and convert that energy directly into electricity, which are coupled to the photoelectrolysis cell as a voltage source for the photoelectrolysis cell device.   
   
   
       15 . A method, comprising:
 heating a solar-energy-to-gas-heat-exchanger and carbon dioxide gas via the addition of the solar power directed from a first set of solar receivers;   splitting water molecules into hydrogen gas and oxygen gas via the addition of the solar power directed from a second set of solar receivers;   producing the hydrogen gas from an aqueous solution in contact with an electrode made of a titanium-based element or compound with a stress-induced band-gap that is shifted and broadened to absorb both wavelengths in a portion of a visible light and in an ultraviolet light spectrum, where the wavelengths are directed from the second set of solar receivers and the band gap of the titanium-based element or compound is shifted and broadened to a band gap of 3.0 electron volts (eV) or lower;   mixing the heated carbon dioxide gas with all of the hydrogen gas from the water splitting process in a reverse-water-gas-shift reaction to produce resultant carbon monoxide and water molecules and unconsumed hydrogen;   quenching a portion of the exit gases from a chemical reactor chamber in which the reverse-water-gas-shift reaction occurs, to stabilize at least the carbon monoxide molecule; and   mixing the unconsumed hydrogen gas and the resultant carbon monoxide from the reverse-water-gas-shift reaction in a hydrocarbon fuel synthesis process to create a liquid hydrocarbon fuel.   
   
   
       16 . The method of  claim 15 , further comprising:
 using a dye sensitized solar cell, which includes a chromophoric substance to chemically create the stress induced band gap.   
   
   
       17 . The method of  claim 15 , further comprising:
 tracking the Sun in two axis of rotation with the second set of solar receivers; and   reflecting the solar energy from the Sun upwards in a frame of a parabolic trough at a focal line of the parabolic trough onto a series of associated light receivers that each contain clear tubes coated with a titanium based element or compound catalyst.   
   
   
       18 . A system, comprising:
 a first array of heliostats to focus solar energy to a solar-energy-to-gas-heat-exchanger to heat carbon dioxide gas via convection heating of the carbon dioxide gas from the heated solar-energy-to-gas-heat-exchanger;   a parabolic trough having multiple mirrors, where each mirror having a rotational frame with two axis of rotation coupled to a tracking actuator to redirect a portion of an electromagnetic spectrum including ultraviolet rays and visible light from the solar energy to a water splitter to split water molecules into hydrogen molecules and oxygen molecules,   one or more photoelectrolysis cells contained in the water splitter, which each have an electrode made of a titanium-based element or compound with a stress-induced band-gap that is shifted and broadened by a formation of surface ripples with a sub-visible-light-wavelength spatial period that causes stress in the titanium based element or compound to shift the bandgap of the titanium based element or compound to support to an absorption of both a portion of the visible light and the ultraviolet rays;   a Nickel alloy based chemical reactor chamber to mix the heated carbon dioxide gas with all of or just a first portion of the hydrogen gas from the water splitter in a reverse-water-gas-shift reaction in order to produce resultant carbon monoxide and water molecules;   a quenching unit to cool at least a portion of the exit gases from the chemical reactor chamber in which the reverse-water-gas-shift reaction occurs, in order to stabilize at least the carbon monoxide molecule in the exit gases; and   a methanol synthesis reactor to mix unconsumed hydrogen molecules and the resultant stabilized carbon monoxide molecules from the reverse-water-gas-shift reaction in a methanol synthesis process to create methanol.   
   
   
       19 . The system of  claim 18 , further comprising:
 a front surface of a reflective mirror portion of each mirror in the parabolic trough is formed by a reflective metal.   
   
   
       20 . The system of  claim 19 , further comprising:
 a polymer or acrylic coating is on top of the front surface of the reflective metal mirror, which is optically transmissive in passing wavelength bands in the electromagnetic spectrum below infrared.