Photosynthetic carbon dioxide sequestration and pollution abatement

• US 8,262,776 B2
• Filed: 10/13/2006
• Issued: 09/11/2012
• Est. Priority Date: 10/13/2006
• Status: Active Grant

• Current Assignee: General Atomics, Inc.
• Original Assignee: General Atomics, Inc.
• Inventors: Hazlebeck, David A., Dunlop, Eric H.
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): MCKENZIE, THOMAS B
• Application Number:
  US11/549,541
• Publication Number:
  US 20080086938A1
• Time in Patent Office: 2,160 Days
• Field of Search: 95/44, 95/45, 95149-240, 95/51, 96234-242, 96243-371, 435/257.1, 4352891-3094, 435/266, 47/14, 423210-248
• US Class Current: 95/149
• CPC Class Codes: C12M 21/02 Photobioreactors culturing algae A01G33/00, A01H4/001, C12N1/12
• CPC Class Codes: C12M 29/26 Conditioning fluids entering or exiting the reaction vessel
• CPC Class Codes: C12M 43/02 Bioreactors or fermenters combined with devices for liquid fuel extraction; Biorefineries
• CPC Class Codes: C12M 43/04 Bioreactors or fermenters combined with combustion devices or plants, e.g. for carbon dioxide removal C12M43/06 takes precedence; recovery of carbon dioxide C12F3/02
• CPC Class Codes: C12M 47/02 Separating microorganisms from the culture medium; Concentration of biomass separating microorganisms from their culture media C12N1/02
• CPC Class Codes: C12M 47/06 Hydrolysis; Cell lysis; Extraction of intracellular or cell wall material lysis of microorganisms C12N1/06; extracting or separating nucleic acids from biological samples C12N15/1003
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02P 60/20 Reduction of greenhouse gas [GHG] emissions in agriculture, e.g. CO2
• CPC Class Codes: Y02W 10/37 using solar energy

Abstract

A system and method for producing biofuel from pollutant-fed algae are disclosed. Specifically, the system includes a scrubber with a chamber for receiving a pollutant-contaminated fluid stream. Further, a scrubber solution is received in the chamber for scrubbing the pollutant-contaminated fluid stream. Also, the system includes a bioreactor that is provided with an input port to receive the scrubber solution with pollutants for use as nutrients to support algae cell growth. Further, the system includes an algae separator that removes the algae from the bioreactor and a device for processing the algae into biofuel. In order to recycle the scrubber solution, the algae separator is in fluid communication with the scrubber. With this arrangement, the effluence from the bioreactor may be recycled for use as the scrubber solution.

Claims

1. A system for producing biofuel from pollutant-fed algae which comprises:

a scrubber having a chamber for receiving a pollutant-contaminated flue gas stream and an outlet for releasing cleaned flue gas;

a liquid scrubber solution received in the chamber for scrubbing the pollutant-contaminated gas stream, wherein the scrubber solution is a sodium-based liquid solution for absorbing carbon-rich pollutants from the pollutant-contaminated gas stream to produce a carbon-rich liquid scrubber solution;

a bioreactor for growing algae cells with high oil content, said bioreactor having an input port for receiving the carbon-rich liquid scrubber solution with absorbed carbon-rich pollutants for use of the absorbed carbon-rich pollutants as nutrients in a medium to support algae cell growth;

an algae separator in fluid communication with the bioreactor for removing the algae cells from the medium to create an effluence;

a channel for recycling the effluence from the algae separator to the scrubber for use as the liquid scrubber solution;

an oil separator in fluid communication with the algae separator for withdrawing oil in the algae from the remaining cell matter;

a channel for recycling the remaining cell matter from the oil separator to a hydrolysis device to produce hydrolyzed cell matter for return to a chemostat of the bioreactor to further support algae cell growth; and

a reactor for receiving the oil from the oil separator and to synthesize biofuel and byproduct from said oil.

2. A system as recited in claim 1 wherein the pollutants are selected from a group comprising carbon dioxide, sulfur oxides and nitrogen oxides.

3. A system as recited in claim 1 wherein the liquid scrubber solution is selected from a group comprising sodium hydroxide and sodium bicarbonate.

4. A system as recited in claim 1 further comprising an oxidation unit for treating the pollutant-contaminated gas stream before being received in the scrubber.

5. A system as recited in claim 4 wherein the oxidation unit oxidizes nitrogen monoxide in the pollutant-contaminated gas stream.

6. A system as recited in claim 1 wherein the bioreactor comprises:

at least one chemostat formed with a conduit for growing algae therein, wherein the chemostat includes the input port for receiving the liquid scrubber solution and for receiving a nutrient mix to form a medium for maximum algae growth, and wherein the chemostat has an output port for passing the medium with algae growth from the conduit of the chemostat;

a means for continuously moving the medium through the conduit of the chemostat at a predetermined fluid flow velocity;

a plug flow reactor formed with a conduit having an input port for receiving the medium with algae growth from the chemostat; and

a means for adding a modified nutrient mix to the medium with algae growth in the plug flow reactor, wherein the modified nutrient mix comprises a limited amount of a selected constituent to trigger high oil production in the algae growth.

7. A system as recited in claim 6 further comprising:

an apparatus for lysing the algae cells removed from the conduit to unbind oil within the algae cells for transfer of the oil from the oil separator to the reactor for synthesizing biofuel and glycerin from said oil; and

a means for recycling at least one byproduct to the bioreactor to support growth of algae cells with high oil content.

8. A system as recited in claim 7 wherein the remaining cell matter is a byproduct and the glycerin is a byproduct.

9. A system for producing biofuel from pollutant-fed algae which comprises:

a means for scrubbing a pollutant-contaminated flue gas stream with a liquid scrubber solution, wherein the liquid scrubber solution is a sodium-based liquid solution for absorbing carbon-rich pollutants from the pollutant-contaminated flue gas stream to produce a carbon-rich liquid scrubber solution, wherein said means for scrubbing comprises an outlet for releasing cleaned flue gas;

a means for feeding the carbon-rich liquid scrubber solution to a bioreactor to form a medium therein to support algae cell growth;

a means for promoting growth of high oil content algae cells in the medium in the bioreactor, with said algae cells converting the absorbed carbon-rich pollutants from the carbon-rich liquid scrubber solution into cell matter during cell growth;

a means for separating the algae cells from the medium in the bioreactor to form an effluence;

a means for recycling the effluence for use as the liquid scrubber solution;

a means for withdrawing oil in the algae cells from the remaining cell matter;

a means for receiving the oil from the means for withdrawing the oil to synthesize biofuel and glycerin from said oil; and

a means for recycling the remaining cell matter from the withdrawing means, for hydrolysis and return as hydrolyzed cell matter to the cell growth promoting means to further support algae cell growth.

10. A system as recited in claim 9 further comprising a means for oxidizing the pollutant-contaminated gas stream.

11. A system as recited in claim 9 wherein the pollutants are selected from a group comprising carbon dioxide, sulfur oxides, and nitrogen oxides.

12. A system as recited in claim 9 wherein the liquid scrubber solution is selected from a group comprising sodium hydroxide and sodium bicarbonate.

13. A method for producing biofuel from pollutant-fed algae which comprises the steps of:

scrubbing a pollutant-contaminated flue gas stream with a liquid scrubber solution in a scrubber, wherein the liquid scrubber solution is a sodium-based liquid solution for absorbing carbon-rich pollutants from the pollutant-contaminated flue gas stream to produce a carbon-rich liquid scrubber solution, wherein said scrubber comprises an outlet for releasing cleaned flue gas;

feeding the carbon-rich liquid scrubber solution to a bioreactor wherein the bioreactor includes at least one chemostat and a plug flow reactor, and wherein the chemostat is formed with a conduit for growing algae therein and an input port for receiving the carbon-rich liquid scrubber solution and a nutrient mix to form a medium for maximum algae growth, with the chemostat having an output port for passing the medium with algae growth from the conduit of the chemostat, and further wherein the plug flow reactor is formed with a conduit having an input port for receiving the medium with algae growth from the chemostat;

growing algae cells with high oil content in the bioreactor, with said algae cells converting the carbon-rich pollutants from the carbon-rich liquid scrubber solution into cell matter during cell growth;

separating the algae cells from an effluence from the bioreactor to create the effluence;

recycling the effluence for use as the liquid scrubber solution;

processing oil from the algae cells to form biofuel;

withdrawing oil in the algae cells from the remaining cell matter;

synthesizing biofuel and byproduct from the oil with a reactor;

hydrolyzing the remaining cell matter from the withdrawing step to create hydrolyzed cell matter; and

recycling the hydrolyzed remaining cell matter to the bioreactor to further support algae cell growth.

14. A method as recited in claim 13 further comprising the step of treating the pollutant-contaminated gas stream before the scrubbing step.

15. A method as recited in claim 14 wherein the treating step includes oxidizing nitrogen oxides in the pollutant-contaminated gas stream.

16. A method as recited in claim 13 wherein the pollutants are selected from a group comprising carbon dioxide, sulfur oxides, and nitrogen oxides.

17. A method as recited in claim 13 wherein the liquid scrubber solution is selected from a group comprising caustic soda and sodium bicarbonate.

18. A method as recited in claim 13 wherein the bioreactor includes at least one chemostat and a plug flow reactor, and wherein the chemostat is formed with a conduit for growing algae therein and an input port for receiving the carbon-rich liquid scrubber solution and a nutrient mix to form a medium for maximum algae growth, with the chemostat having an output port for passing the medium with algae growth from the conduit of the chemostat, and further wherein the plug flow reactor is formed with a conduit having an input port for receiving the medium with algae growth from the chemostat, with the method further comprising the steps of:

continuously moving the medium through the conduit of the chemostat at a predetermined fluid flow velocity; and

adding a modified nutrient mix to the medium with algae growth in the plug flow reactor, wherein the modified nutrient mix comprises a limited amount of a selected constituent to trigger high oil production in the algae growth.

19. A method as recited in claim 18 wherein the processing step includes:

lysing the algae cells removed from the conduit to unbind oil within the algae cells; and

withdrawing the oil from remaining cell matter.

20. A method as recited in claim 19 wherein the remaining cell matter is a byproduct and glycerin is a byproduct, and wherein the processing step includes recycling at least one byproduct to the bioreactor to support growth of algae cells with high oil content.