An initial assessment for the use of seawater as a method to remove metabolically-produced carbon dioxide from a submersible atmosphere

Traditional CO2 absorption methods that are integrated into underwater life support systems use alkali metal hydroxide chemical beds—mostly calcium hydroxide—which have been shown to have poor absorption efficiencies at cold temperatures, and must be replaced at considerable trouble and expense on a frequent basis. With chemical utilizations as low as 20% in water temperatures of 2 °C, these hydroxides do not lend themselves to applications requiring extended durations due to the inability to carry sufficient quantities of these expendables. Experimental evidence suggests that seawater, a readily accessible medium during submersible operations, could be a highly efficient scrubbing medium to remove metabolically-produced carbon dioxide, particularly in cold water missions. This paper describes a feasibility assessment for using seawater to remove metabolically-produced carbon dioxide from a submersible atmosphere and proposes a multi-path scrubber design for use as an underwater life support system.