Sequestration of carbon dioxide into underground structures

A system for sequestering carbon dioxide;

• the system comprising:
• an underground structure, comprising fractured and cracked rock;
• a separator that operates on an input gas mixture comprising carbon dioxide gas and one or more other gases, providing a separated carbon dioxide gas output;
• a compressor that compresses the separated carbon dioxide gas output to a pressure in a predetermined pressure range, providing a second output comprising at least one of gaseous carbon dioxide and liquid carbon dioxide;
• a mixer that provides a third output by mixing the second output with liquid water at a pressure in the predetermined range, the third output comprising:
• at least one of liquid carbon dioxide and gaseous carbon dioxide;
• and
• water with dissolved carbon dioxide;
• and
• a pump that pumps the third output into the underground structure under a pressure in the predetermined range, such that components of the third output react with the fractured and cracked rock in and around the underground structure to form stable carbonates.

A method for sequestering carbon dioxide underground in an underground structure, comprising fractured and cracked rock;

• the method comprising:
• a first method for separating carbon dioxide gas from one or more other gases in an input gas mixture to provide a separated carbon dioxide gas output;
• a second method for compressing the separated carbon dioxide gas output to a pressure in a predetermined range, providing a second output comprising at least one of gaseous carbon dioxide and liquid carbon dioxide;
• a third method for providing a third output mixture by mixing the second output with liquid water at a pressure in the predetermined range, the third output mixture comprising:
• at least one of liquid carbon dioxide and gaseous carbon dioxide;
• and
• water with dissolved carbon dioxide;
• and
• a fourth method for pumping the third output mixture under a pressure in the predetermined range into the underground structure, such that components of the third output mixture react with the fractured and cracked rock in and around the underground structure to form stable carbonates.