Feasibility Study of Using Brine for Carbon Dioxide Capture and Storage from Fixed Sources

Abstract

A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO 2 ) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO 2 at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media-tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO 2 to carbonic acid. The transferred CO 2 formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca ϩϩ , produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO 2 , with less than a 6% reduction in CO 2 transferred. The CO 2 either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We conclude that using brine in a gas-exchange membrane system for capturing CO 2 from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy.

Thermodynamic Feasibility of Enzymatic Reduction of Carbon Dioxide to Methanol

“…However, Δ r G 0 i o for CO 3 2− deviates from the others significantly as pH value decreases, thus suggesting that CO 3 2− is the preferred substrate at acidic conditions.…”

“…CO 3 2− was taken as the substrate for these calculations. Overall, the theoretical prediction generally agreed well with most of the reported yields of methanol, considering that most of the studies were conducted not under strictly controlled conditions for equilibrium evaluations.…”

“…One strategy is to sequester CO 2 at its emission sources and bury it underground or in the ocean [1]. Since 1990, a variety of chemical [2][3][4], electrochemical [5], and biological [6][7][8][9] methodologies have been examined for CO 2 sequestration [10]. One profitable way, however, is to produce valuable chemicals even fuels from CO 2 .…”

Carbonic anhydrase mediated carbon dioxide sequestration: Promises, challenges and future prospects

“… also studied similar kind of bioreactor by using a gas–liquid membrane exchanger. CO 2 rich gas was reacted with CA and after solubilization the liquid phase was routed into other module where it reacted with calcium to produced CaCO 3 . Bao and Trachtenberg described classical counter‐current packed CO 2 absorber with immobilized CA.…”

“…This is due to variety of challenges pertaining to CA mediated CO 2 sequestration. For example, membrane bioreactor reported by Trachtenberg [62] and Dziedzic et al [63] had problem with pressure change in membrane fibers. Counter current bioreactor developed by Bao and Trachtenberg [64] was designed to enhance CO 2 gasliquid transfer rate by hydrating aqueous CO 2 to HCO 3 À .…”