Electrochemical system for carbon dioxide capture

A method for capturing carbon dioxide from a gas stream, comprising:

• applying a potential difference between an anode and a cathode in an electrochemical cell containing an electrolytic solution such that alkali metal ions are formed in the electrolytic solution at the anode,
• permitting the alkali metal ions to diffuse through a proton or cation exchange membrane between the anode and the cathode, towards the cathode to react with hydroxide ions to form an alkali metal base,
• separating the alkali metal base from the electrolytic solution,
• contacting the gas stream comprising carbon dioxide with the alkali metal base such that the carbon dioxide reacts with the alkali metal base to form a carbonate, thus capturing the carbon dioxide from the gas stream.

An electrochemical system for capturing carbon dioxide from a gas stream and generating methane, the system comprising:

• an electrochemical cell comprising an anode chamber and a cathode chamber, where the cell contains an electrolyte solution;
• a cathode exposed to the electrolyte solution in the cathode chamber;
• an anode exposed to the electrolyte solution in the anode chamber;
• a power supply electrically connected to the anode and the cathode configured to apply a potential difference between the anode and the cathode;
• a proton or cation exchange membrane separating the anode chamber and the cathode chamber allowing alkali metal ions formed at the anode to diffuse through the proton or cation exchange membrane towards the cathode to react with hydroxide ions to form an alkali metal base,
• a collection chamber to collect the alkali metal base from the cathode chamber;
• a source of the gas stream comprising carbon dioxide for contacting with the alkali metal base such that the carbon dioxide reacts with the alkali metal base to form a carbonate, and thus capture the carbon dioxide from the gas stream,
• a deoxygenation unit to remove dissolved oxygen from the carbonate solution to produce a deoxygenated carbonate solution,
• and
• a biomethane production module configured to receive the deoxygenated carbonate solution, the biomethane production module comprising biocatalysts to react with the carbonate to produce methane.