Systems and methods of storing combustion waste products
In one aspect, methods of storing one or more combustion waste products are described herein. Combustion waste products stored by a method described herein can include solid combustion waste products such as coal ash and/or gaseous combustion products such as carbon dioxide. In some embodiments, a method of storing carbon dioxide comprises providing a carbon dioxide storage medium comprising porous concrete having a macroporous and microporous pore structure and flowing carbon dioxide captured from a combustion flue gas source into the pore structure of the porous concrete.
1. A method of storing carbon comprising:
providing a carbon dioxide storage medium comprising porous concrete having a macroporous and microporous pore structure; and
flowing carbon dioxide captured from a combustion flue gas source into the pore structure of the porous concrete,
wherein the porous concrete has a porosity of about 10 percent to about 70 percent and comprises macropores having a diameter between about 200 μm and about 800 μm and micropores having a diameter between about 100 nm and about 20 μm.
2. The method of claim 1 , wherein the porous concrete comprises a mixture of coal ash and cement.
3. The method of claim 1 , wherein the carbon dioxide is sorbed by the porous concrete at a rate of at least 0.01 grams of carbon dioxide per gram of porous concrete per minute.
4. The method of claim 1 , wherein the carbon dioxide is chemisorbed and physisorbed by the porous concrete.
5. The method of claim 1 , wherein the concentration of carbon dioxide flowed into the pore structure of the porous concrete is greater than the atmospheric concentration of carbon dioxide.
6. The method of claim 1 , wherein flowing carbon dioxide into the pore structure of the porous concrete comprises disposing the carbon dioxide in the porous concrete in an amount of 5 to 33 weight percent, based on the total weight of the porous concrete.
7. The method of claim 1 , wherein the porous concrete is at least partially uncured.
8. The method of claim 1 , wherein the porous concrete is substantially cured.
9. The method of claim 1 , wherein flowing carbon dioxide into the pore structure of the porous concrete comprises:
providing an uncured porous concrete composition; and
curing the uncured porous concrete composition in the presence of the carbon dioxide.
10. The method of claim 9 , wherein the uncured porous concrete composition comprises coal ash, cement, water, and a blowing or foaming agent.
11. The method of claim 9 , wherein the uncured porous concrete composition has an acidic pH.
12. The method of claim 9 , wherein curing is carried out at a pressure of 30 psi to 500 psi.
13. The method of claim 9 , wherein curing is carried out at a constant temperature.
14. The method of claim 9 , wherein curing is carried out at ambient temperature.
15. A method of backfilling comprising disposing a backfill material in a void to at least partially fill the void, the backfill material comprising:
porous concrete having a macroporous and microporous pore structure and carbon dioxide residing within the porous concrete in an amount greater than 1 weight percent of the porous concrete,
wherein the porous concrete has a porosity of about 10 percent to about 70 percent and comprises macropores having a diameter between about 200 μm and about 800 μm and micropores having a diameter between about 100 nm and about 20 μm.
16. The method of claim 15 , wherein the porous concrete comprises a mixture of coal ash and cement.
17. The method of claim 1 , wherein the carbon dioxide is present in the carbon dioxide storage medium at a depth of more than 5 cm from the surface of the porous concrete.
18. The method of claim 1 , wherein flowing carbon dioxide into the pore structure of the porous concrete comprises flowing compressed carbon dioxide into the porous concrete.
19. The method of claim 1 , wherein the coal ash is present in the porous concrete in an amount between 5 weight percent and 90 weight percent, based on the total weight of the porous concrete.