Carbon dioxide isolation and generation
Methods and apparatus for collecting/concentrating carbon dioxide are disclosed. In addition, methods and apparatus for utilizing collected carbon dioxide in biofuel production and biomass cultivation are disclosed.
1. A method for generating CO 2 , comprising:
exposing a gas comprising CO 2 to an aqueous material comprising hydroxide ions and more than about 20% water and having a pH of about 8.5 or above, whereby at least a portion of the CO 2 is dissolved in the aqueous material;
subjecting the aqueous material comprising the dissolved CO 2 to an electrical potential in an electrochemical cell, wherein the electrical potential oxidizes at least a portion of the hydroxide ions to water, wherein the electrochemical cell has a first electrochemical half-cell, a second electrochemical half-cell, and a proton exchange membrane, wherein the electrochemical cell has an electrical energy requirement for releasing the dissolved CO 2 as a gas and the electrical energy requirement for releasing the dissolved CO 2 is less than about 350 KJ/mole of CO 2 ; and
releasing at least a portion of the dissolved CO 2 .
2. The method of claim 1 , wherein the proton exchange membrane separates an anode from a cathode.
3. The method of claim 1 , wherein the aqueous material comprising the dissolved CO 2 is exposed to the electrical potential in the first electrochemical half-cell and the first half cell utilizes hydrogen and the second half cell generates hydrogen.
4. The method of claim 3 , wherein the first half cell utilizes a first amount of hydrogen and the second half cell generates a second amount of hydrogen, and the first amount of hydrogen is within about 10% of the second amount of hydrogen.
5. The method of claim 1 , wherein the second half-cell utilizes oxygen, and the first half-cell generates oxygen.
6. The method of claim 5 , wherein the second half cell utilizes a first amount of oxygen and the first half cell generates a second amount of oxygen, and the first amount of oxygen is within 10% of the second amount of oxygen.
7. The method of claim 1 , wherein the gas comprising CO 2 is obtained from at least one source selected from the group consisting of the atmosphere, a power plant, a boiler, a fermentation facility, an underground deposit, an oil well, a natural gas well, a petroleum refinery, a cement factory, an iron production facility, a steel production facility, a waste combustion facility, a chemical production facility, a metal production facility, and combinations thereof.
8. The method of claim 1 , wherein half reactions take place in the first and second electrochemical cells, and the sum of the E 0 values for the half reactions is about 0.
9. The method of claim 1 , wherein the electrochemical cell has an electrical energy requirement for releasing the dissolved CO 2 as a gas, wherein the electrical energy requirement is less than about 200 KJ/mole CO 2 .
10. The method of claim 1 , wherein the electrochemical cell has an electrical energy requirement for releasing the dissolved CO 2 as a gas, wherein the electrical energy requirement is less than about 100 KJ/mole CO 2 .
11. The method of claim 1 , wherein the released CO 2 is present in a gas phase at a concentration of greater than about 50% (vol.).
12. The method of claim 1 , wherein the released CO 2 is present in a gas phase at a concentration of greater than about 80% (vol.).
13. The method of claim 1 , wherein one of the first and second electrochemical half cells includes an anode, and half reactions take place in the electrochemical half cell which includes the anode, and during operation, the half reactions that take place in the electrochemical half cell whicn which includes the anode do not consist of:
H 2 →2H + +2 e − .