Enhanced CO2 Removal and Disposal for Diver Rebreather Applications
Abstract
Rebreathers are essential for underwater diving operations where stealth and obscurity are demanded by the mission. To recycle expelled breath within a self-contained system, metabolically generated carbon dioxide (CO2) is removed from a diver#s exhalant, thus allowing oxygen to be returned, thereby extending the duration of the diving operation. The CO2 is removed by passing the exhalant through the rebreather whereupon CO2 is efficiently sequestered and stored by the rebreather in a non-gaseous form. At the heart of the rebreather is the chemical adsorbent that reacts with CO2 to produce a solid carbonate salt, which is disposed of or regenerated upon the completion of the diving operation. Thus, the rebreather must be carried on the back of the diver from beginning-to-end of the diving mission. This proposal addresses the development of the science for future diving operations where CO2 is removed from the diver#s exhalant #on-the-fly#, thereby eliminating the need for a rebreather. This proposal involves a multidisciplinary MIT/Harvard team of researchers to remove CO2 from O2 with newly designed membranes and then convert, with newly designed catalysts, the separated CO2 to a soluble liquid or salt form for their direct disposal into seawater. The purified oxygen is then available for return to the diver#s inhalant. Stepping beyond traditional membrane size sieving mechanisms for separating CO2 from other gases in expelled breath, the fundamental science of facilitated transport will be investigated in microporous membrane materials to enable highly selective CO2 transport. To achieve this objective, CO2-philic groups will be systematically incorporated into polymers of intrinsic microporosity (PIMs) and metal#organic frameworks (MOFs) to selectively and reversibly react with and transport CO2 over other gases. Novel electrochemical catalysts will be developed to reduce the membrane-separated CO2 to water soluble C1 salts and C2/2+ alcohols that can be undetectably dispelled into seawater. The science resulting from the program will offer greater flexibility in undersea operations as the bulk of the diver#s backpack is ultimately not needed to accomplish the re-breathing processes. Consequently, new capabilities are available for multi-domain operations as a backpack would not need to be managed during sea-land transitions. This technology could also be utilized for other applications, such as submarine environments where CO2 removal may be accomplished with greater energy efficiency without the need of the hazardous solvents that are currently employed for CO2 sequestration.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 13, 2025
- Source ID
- N000142512100
Entities
People
- Zachary P Smith
Organizations
- Massachusetts Institute of Technology
- Office of Naval Research
- United States Navy