In a general aspect, a carbon dioxide (CO.sub.2) removal system uses geothermal energy. In some implementations, a method to remove CO.sub.2 gas from a gaseous feed includes directing a gaseous feed to interact with an alkaline capture solution in a first gas-liquid contactor. A first portion of CO.sub.2 from the gaseous feed dissolves into the alkaline capture solution to form a CO.sub.2-rich alkaline capture solution. Steam is generated using heat from a geothermal heat source, and the steam heats the CO.sub.2-rich alkaline capture solution in a second gas-liquid contactor. A second portion of the CO.sub.2 is separated from the CO.sub.2-rich alkaline capture solution in the second gas-liquid contactor to form a CO.sub.2-lean alkaline capture solution. The CO.sub.2-lean alkaline capture solution is directed to the first gas-liquid contactor.

In a general aspect, a carbon dioxide (CO.sub.2) removal system uses geothermal energy. In some implementations, a method to remove CO.sub.2 gas from a gaseous feed includes directing a gaseous feed to interact with an alkaline capture solution in a first gas-liquid contactor. A first portion of CO.sub.2 from the gaseous feed dissolves into the alkaline capture solution to form a CO.sub.2-rich alkaline capture solution. Steam is generated using heat from a geothermal heat source, and the steam heats the CO.sub.2-rich alkaline capture solution in a second gas-liquid contactor. A second portion of the CO.sub.2 is separated from the CO.sub.2-rich alkaline capture solution in the second gas-liquid contactor to form a CO.sub.2-lean alkaline capture solution. The CO.sub.2-lean alkaline capture solution is directed to the first gas-liquid contactor.

In a general aspect, a carbon dioxide (CO.sub.2) removal system uses geothermal energy. In some implementations, a method to remove CO.sub.2 gas from a gaseous feed includes directing a gaseous feed to interact with an alkaline capture solution in a first gas-liquid contactor. A first portion of CO.sub.2 from the gaseous feed dissolves into the alkaline capture solution to form a CO.sub.2-rich alkaline capture solution. Steam is generated using heat from a geothermal heat source, and the steam heats the CO.sub.2-rich alkaline capture solution in a second gas-liquid contactor. A second portion of the CO.sub.2 is separated from the CO.sub.2-rich alkaline capture solution in the second gas-liquid contactor to form a CO.sub.2-lean alkaline capture solution. The CO.sub.2-lean alkaline capture solution is directed to the first gas-liquid contactor.