INTEGRATED CARBON CAPTURE AND ALGAE CULTURE

• US 20130319059A1
• Filed: 12/09/2011
• Published: 12/05/2013
• Est. Priority Date: 12/09/2010
• Status: Abandoned Application

• Current Assignee: Washington State University
• Original Assignee: Washington State University
• Inventors: Chen, Shulin, Chi, Zhanyou, Xie, Yuxiao, Zhao, Baisuo
• Application Number:
  US13/992,291
• Publication Number:
  US 20130319059A1
• Time in Patent Office: Days
• US Class Current: 71/23
• CPC Class Codes: B01D 2251/95 Specific microorganisms
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/60 Simultaneously removing sulfur oxides and nitrogen oxides
• CPC Class Codes: B01D 53/84 Biological processes
• CPC Class Codes: C05F 11/00 Other organic fertilisers
• CPC Class Codes: C12M 21/02 Photobioreactors culturing algae A01G33/00, A01H4/001, C12N1/12
• 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: C12N 1/12 Unicellular algae; Culture media therefor as new plants A01H13/00
• CPC Class Codes: C12P 19/04 Polysaccharides, i.e. compounds containing more than five saccharide radicals attached to each other by glycosidic bonds
• CPC Class Codes: C12P 23/00 Preparation of compounds containing a cyclohexene ring having an unsaturated side chain containing at least ten carbon atoms bound by conjugated double bonds, e.g. carotenes containing heterorings C12P17/00
• CPC Class Codes: C12P 7/64 Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
• CPC Class Codes: C12P 7/6427 Polyunsaturated fatty acids [PUFA], i.e. having two or more double bonds in their backbone
• CPC Class Codes: C12P 7/649 Biodiesel, i.e. fatty acid alkyl esters
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2
• CPC Class Codes: Y02P 20/59 Biological synthesis; Biological purification
• CPC Class Codes: Y02W 30/40 Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse

Abstract

The feasibility of using CO₂ from a concentrated source to grow microalgae is limited by the high cost of CO₂ capture and transportation, as well as significant CO₂ loss during algae culture. Another challenge is the inability of algae in using CO₂ during night while CO₂ is continuously produced from the source. To address these challenges, this invention provides a process in which CO₂ is captured as bicarbonate and used as feedstock for algae culture. Then the carbonate is regenerated in the algae culture process as absorbent to capture more CO₂, which is converted to bicarbonate for use as feedstock, etc. This process significantly reduces carbon capture costs since it avoids the energy for carbonate regeneration. Also, transporting a solid or aqueous bicarbonate solution has a much lower cost than transporting compressed CO₂, and using bicarbonate provides a better alternative for CO₂ delivery to algae culture systems than supplying CO₂ gas.

Claims

1. An integrated method culturing algae or cyanobacteria, comprising the steps of

i) capturing CO₂ from a source of CO₂;

ii) converting captured CO₂ into bicarbonate;

iii) culturing alkaliphilic algae or alkaliphilic cyanobacteria using said bicarbonate as a carbon source to produce algal bioproducts;

iv) using spent medium from said step of culturing as said source of CO₂ in said step of capturing; and

v) repeating steps i) to iv).

2. The method of claim 1, wherein said bicarbonate is in a form selected from the group consisting of solid bicarbonate and a liquid bicarbonate solution.

3. The method of claim 1, wherein said alkaliphilic cyanobacteria are selected from the group consisting of Synechocystis sp., Cyanothece sp., Microcoleus sp., Euhalothece sp. and Spirulina sp.

4. The method of claim 1, wherein said alkaliphilic algae are eukaryotic microalgae selected from the group consisting of Chlorella and Dunaliella.

5. The method of claim 1, wherein culture medium used in said step of culturing has a concentration in a range of from 0.01 mol/L bicarbonate to saturation.

6. The method of claim 5, wherein culture medium used in said step of culturing has a concentration in a range of from 0.03 mol/L bicarbonate to saturation.

7. The method of claim 1, wherein culture medium used in said step of culturing is carried out at a pH of from 8.0 to 12.

8. The method of claim 7, wherein culture medium used in said step of culturing is carried out at a pH of from 9.0 to 11.

9. The method of claim 1, wherein said step of capturing is carried out using a method selected from the group consisting of:

using salt of carbonate as absorbent, using carbonic anhydrase as catalyst, and using ammonia and sodium chloride as feedstock to produce bicarbonate.

10. The method of claim 1, wherein said CO₂ source is selected from the group consisting of:

thermal power plant emissions, a fermentation process, an anaerobic digestion process, an ammonia plant, and air.

11. The method of claim 2, wherein said liquid bicarbonate solution has a concentration in the range of 0.01 mol/L to saturation.

12. The method of claim 11, wherein said liquid bicarbonate solution has a concentration in the range of 0.3 mol/L to saturation.

13. The method of claim 1, wherein said alkaliphilic algae or said alkaliphilic cyanobacteria utilizes bicarbonate as a sole carbon source.

14. The method of claim 1, wherein said alkaliphilic algae or said alkaliphilic cyanobacteria utilizes bicarbonate as one of more than one carbon sources.

15. The method of claim 1, wherein said step of culturing is performed in an algae culture system selected from the group consisting of an open pond system and a closed photo-bioreactor system.

16. The method of claim 1, wherein said step of culturing is conducted in batch culture, semi-continuous culture, or continuous culture.

17. The method of claim 1, wherein said bicarbonate is a salt selected from the group consisting of sodium, potassium and ammonium.

18. The method of claim 1, further comprising the step of obtaining from said alkaliphilic algae or said alkaliphilic cyanobacteria a product selected from the group consisting of algae oil for biofuel, algae oil for nutraceuticals, omega-3 fatty acids, pigments, carotenoids, alginate, and fertilizer.

19. The method of claim 1, wherein steps of capturing CO₂ from a source of CO₂ and converting CO₂ into bicarbonate are carried out as a single step.

20. The method of claim 1, further comprising a step vi) of recovering said bioproducts.

21. An integrated system for culturing algae or cyanobacteria, comprising

an apparatus for capturing CO₂ from a source of CO₂;

an apparatus for converting CO₂ to bicarbonate;

a culture system for culturing alkaliphilic algae or alkaliphilic cyanobacteria using said bicarbonate; and

transport means for

i) transporting captured CO₂ from said source of CO₂ to said apparatus for converting CO₂ to bicarbonate; and

ii) transporting bicarbonate from said apparatus for converting CO₂ to bicarbonate to said culture system.

22. The integrated system of claim 21, wherein said culture system optionally comprises a pH control system and/or a CO₂ bubbling system.

23. The integrated system of claim 21, wherein said bicarbonate is in a liquid solution and said transport means is selected from the group consisting of a closed pipeline, an open pipeline, and a tank.

24. The integrated system of claim 21, wherein said bicarbonate is a solid and said transport means is selected from the group consisting of a truck and a railroad car.

25. The integrated system of claim 21, wherein said apparatus for capturing CO₂ from a source of CO₂ and said apparatus for converting CO₂ to bicarbonate are a single apparatus.