Carbon Neutralization System (CNS) for CO2 sequestering

• US 20070092962A1
• Filed: 10/11/2006
• Published: 04/26/2007
• Est. Priority Date: 10/20/2005
• Status: Abandoned Application

• Current Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Original Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Inventors: Sheppard, Norman
• Application Number:
  US11/546,104
• Publication Number:
  US 20070092962A1
• Time in Patent Office: Days
• US Class Current: 435/266
• CPC Class Codes: C12M 21/02 Photobioreactors culturing algae A01G33/00, A01H4/001, C12N1/12
• CPC Class Codes: C12M 21/04 for producing gas, e.g. biogas digesters for manure with production of biogas A01C3/028, biological treatment of water, waste water or sewage C02F3/00, C02F11/02, preparation of natural gas or syngas C10L3/06, C10L3/10
• CPC Class Codes: C12M 23/04 Flat or tray type, drawers C12M23/10, C12M23/12, C12M23/16 take precedence
• CPC Class Codes: C12M 31/10 by light emitting elements located inside the reactor, e.g. LED or OLED
• 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

Abstract

A device and method for carbon dioxide sequestering involving the use of a photo-bioreactor with Light Emitting Diodes (LED'"'"'s) for the cost-effective photo-fixation of carbon dioxide (CO₂). This device and method is useful for removing undesirable carbon dioxide from waste streams.

Claims

1. A device for the photofixation of CO₂, the device comprising:

an outer wall, the outer wall defining a containment area;

a CO₂-rich gas source operable to provide CO₂-rich gas into the containment area;

a plurality of trays housed within the containment area, the trays having a bottom and two sides, the trays being operable to circulate within the trays an aquatic culture of a photosynthetic organism operable to convert CO₂-rich gas to O₂-rich gas, the trays defining holes having an original average diameter, the holes operable to allow for the passage of the CO₂-rich gas through the trays;

an artificial light source operable to radiate the aquatic culture, the artificial light source operable to deliver intermittent flashes of light centered on a preselected wavelength range, the intermittent flashes being deliverable with a predetermined frequency and duration of light and a predetermined period wherein the artificial light source does not emit light; and

an exhaust line operable to receive the converted CO2-rich gas as an exhaust stream from the containment area.

2. The device of claim 1, further comprising a conveyance apparatus, the conveyance apparatus being in communication with the aquatic culture such that the conveyance apparatus is operable to promote circulation of the aquatic culture along the trays with laminar flow.

3. The device of claim 2, wherein the conveyance apparatus comprises an Archimedes'"'"' screw.

4. The device of claim 2, wherein the conveyance apparatus comprises a reciprocal pump.

5. The device of claim 1, further comprising a recycle line in communication between the exhaust line and the CO₂-rich gas source such that at least a portion of the exhaust stream is directed into communication with the CO2-rich gas source for introduction into the containment area.

6. The device of claim 1, wherein the trays include a top.

7. The device of claim 6, wherein the top of one tray in conjunction with the bottom and sides of one tray defines an enclosed tray area.

8. The device of claim 7, further comprising the step of controlling a gas pressure differential between the enclosed tray area and the containment area

9. The device of claim 8, wherein the gas pressure differential is controlled through the use of a pressure regulator.

10. The device of claim 6, wherein the artificial light source is embedded in the top of at least one tray.

11. The device of claim 1, wherein the artificial light source is operable to deliver intermittent flashes of light in the wavelength range 660 nm+/−

10 nm

12. The device of claim 1, wherein the artificial light source is operable to deliver the intermittent flashes with a frequency of less than one second and a duration of less than 0.1 seconds

13. The device of claim 1, wherein the trays generally define a rectangular cross-section and wherein the bottoms of at least a portion of the plurality of the trays are inclined from horizontal such that flow of the aquatic culture through at least a portion of the plurality of trays is enhanced by gravity.

14. The device of claim 1, wherein the trays are made of a transparent material for at least the bottom or one side, such that the light centered on a narrow wavelength passes through the transparent material.

15. The device of claim 14, wherein the transparent material comprises polycarbonate.

16. The device of claim 1, wherein the flow of the aquatic culture defines a flow rate through the trays, the flow rate being generally less than two meters per second.

17. The device of claim 1, further comprising a filter in communication with the aquatic culture, the filter being operable to remove at least a portion of the photosynthetic organism from the tray.

18. The device of claim 1, wherein the photosynthetic organism comprises a type of cyanobacteria.

19. The device of claim 18, wherein the cyanobacteria comprises blue-green algae.

20. The device of claim 1, wherein the trays further comprises a non-stick material on at least a portion of an inner surface of the tray, the inner surface being in communication with the photosynthetic organism, the non-stick material being selected to minimize adhesion between the non-stick material and the photosynthetic organism.

21. The device of claim 20, wherein the non-stick material comprises of polytetrafluoroethlyene.

22. The device of claim 1, wherein the original average diameter of the holes defined by the trays is smaller that an average diameter of the photosynthetic organism.

23. The device of claim 1, wherein the artificial light source consists of light emitting diodes.

24. The device of claim 1, wherein the artificial light source is embedded in the bottom or at least one side of the tray.

25. The device of claim 1, where the intermittent flashes are delivered with a frequency of about less than one second and a duration of about less than 0.1 seconds.

26. The device of claim 1, wherein the outer wall includes movable shades being operable to allow natural sunlight to radiate the aquatic culture.

27. The device of claim 1, wherein the CO2-rich gas source is a waste gas from an industrial process.

28. A method of photofixation of CO₂, the method comprising the steps of:

circulating of an aquatic culture comprised of a photosynthetic cyanobacteria, the aquatic culture being circulated on a plurality of trays, the trays being contained within an outer wall, the outer wall defining a containment area, the trays having a bottom and two sides;

providing CO2-rich source gas into the containment area such that the CO2-rich source gas contacts the aquatic culture;

irradiating the aquatic culture through the use of an artificial light source, the artificial light source having a plurality of light emitting diodes operable to deliver intermittent flashes of light centered on a preselected wavelength range, the intermittent flashes being deliverable with a predetermined frequency and duration of light and a predetermined period wherein the artificial light source does not emit light;

sequestering a portion of the carbon from the CO₂-rich source gas within the cyanobacteria through the process of photosynthesis to produce an exhaust stream, the exhaust stream having a reduced quantity of CO₂ as compared to the CO2-rich source gas; and

removing the exhaust stream from the containment area.

29. The method of claim 28, wherein the bottom of the trays define a plurality of holes such that the CO₂-rich source passing through the holes contacts the aquatic culture, the holes having an original average diameter.

30. The method of claim 28, further comprising the step of promoting circulation of the aquatic culture using a conveyance apparatus, the conveyance apparatus being in communication with the aquatic culture such that the aquatic culture moves with laminar flow.

31. The method of claim 28, wherein the conveyance apparatus comprises an Archimedes'"'"' screw.

32. The method of claim 28, wherein the conveyance apparatus comprises a reciprocal pump.

33. The method of claim 28, further comprising the step of recycling at least a portion of the exhaust gas into the containment area for further contact with the aquatic culture.

34. The method of claim 28, further comprising the step of capturing O₂ produced by the photosynthetic cyanobacteria in the exhaust stream.

35. The method of claim 28, further comprising the step of irradiating the aquatic culture with natural sunlight.

36. The method of claim 28, further comprising the step of filtering at least a portion of the cyanobacteria on the tray.

37. The method of claim 28, wherein circulation of the aquatic culture through at least a portion of the plurality of the trays is enhanced by the gravity through the portion of the plurality of trays being placed at an incline to the horizontal.

38. The method of claim 28, wherein at least a portion of the trays is made of a transparent material, facilitating irradiation by the light emitting diodes.

39. The method of claim 28, wherein the aquatic culture circulates through the trays at a speed of about less than 2 meters per second.

40. The method of claim 28, wherein at least a portion of the trays is lined with a non-stick material such that adhesion of cynobacteria to the trays is reduced.

41. The method of claim 28, wherein the original average diameter of the holes defined by the trays is less that an average diameter of the cyanobacteria.

42. The method of claim 28, wherein pressure within the containment area of the CO₂-rich source gas on the tray bottoms discourages the aqueous culture from flowing through holes defined by the trays.

43. The method of claim 28, wherein the tray further comprises a top such that the bottom, sides and top defines an enclosed tray area.

44. The method of claim 43, further comprising the step of controlling a gas pressure differential between the enclosed tray area and the containment area

45. The method of claim 43, wherein the gas pressure differential is controlled through the use of a pressure regulator.

46. The method of claim 28, wherein the gas velocity through the holes defined by the trays is less than about 40 meters per second.