• Number 336  |
• May 2, 2011

Carbon capture, sequestration processes patented

DOE's National Energy Technology Laboratory recently received patents for two carbon capture/sequestration processes.

The first was for an enhanced version of amine-based scrubbing, which couples kinetic rate enhancements with phase separation of CO and chemical regeneration of the amine solution, to separate CO₂ from flue gas. As illustrated in the figure, the CO₂ is absorbed into an amine-bearing solution containing dissolved sodium or potassium carbonate. The dissolved CO₂ reacts with the carbonate to form the corresponding bicarbonate, which precipitates from solution in a semi-crystalline form. The separated bicarbonate solid is then heated to release CO₂ and regenerate the carbonate reagent, thus avoiding the energy penalty associated with heating of the bulk amine solution. In an alternative configuration of this novel process, the CO₂-loaded amine solutions are used to promote rapid carbonation of solid streams with significant carbonation potential (e.g., waste cement, CaO-bearing fly ash, and other industrial by-product streams). Through this carbonation, CO₂ is sequestered as a stable mineral carbonate and the CO2 capture capacity of the amine solution is chemically regenerated.

The U.S. Patent and Trademark Office also recently granted NETL a patent (U.S. Patent 7,922,792) for a method to capture and sequester both CO₂ and SO₂ from waste gas streams using waste by-products, specifically bauxite residue from aluminum production and brine from oil/gas production. The patented acid gas trapping approach combines separation and storage in a single step. The integrated use of bauxite residue/brine mixtures in the process provides a cost effective means of direct flue gas treatment and could be an attractive option for industrial sources located near bauxite residue tailings disposal sites.

[Linda Morton, 304.285.4543,
Linda.morton@netl.doe.gov]