Energy efficient removal of co2 from air by integrating with h2 generation

A method of removing carbon dioxide from an atmosphere and generating hydrogen, comprising:

• capturing carbon dioxide from an atmosphere in an alkaline capture solution;
• sending the alkaline capture solution to a series of electrolyzers in a CO2-rich path, wherein each electrolyzer cell raises the acidity of the input CO2-rich solution;
• removing carbon dioxide from the acidified CO2-rich solution at a removal unit operation to produce a CO2-poor solution;
• sending the CO2-poor solution to the series of electrolyzers in a return path, wherein each electrolyzer raises the alkalinity of the return CO2-poor solution;
• and
• returning the basified CO2-poor solution to the carbon dioxide capture unit operation.

An electrolyzer, comprising:

• a first chamber to receive a first input stream, the first chamber to produce a first output stream that is more acidic than the first input stream;
• a first electrode in the first chamber;
• a second chamber to receive a second input stream, the second chamber to produce a second output stream that is more alkaline than the second input stream;
• a second electrode in the second chamber;
• a voltage source connected to the electrodes;
• and
• an ion-selective membrane separating the first chamber from the second chamber,
• wherein the electrolyzer is configured to control flows of the first input stream and the second input stream to reduce a local pH drop across the ion-selective membrane.