Paul J.T. Straatman with Wilfried G.J.H.M. van Sark has published “Indirect Air CO2 Capture and Refinement based on OTEC Seawater Outgassing,” which is available on iScience: https://doi.org/10.1016/j.isci.2021.102754
The paper proposes utilizing Open OTEC (an OTEC cycle that utilizes a vacuum chamber to lower the boiling point of surface ocean water, creating low-pressure steam to expand a turbine prior to condensation through use of deep ocean water) to extract CO2 from ocean water rather than air given the higher concentration of CO2 in ocean water. The authors propose that atmospheric CO2 could then be reduced as CO2 is naturally reabsorbed by the oceans.
Editorial: We would like to note that while open cycle OTEC may produce some non-condensable gasses such as CO2 during the vacuum process, depending on the ocean water ducting systems utilized, closed, hybrid, or even open ocean thermal cycles may reduce or eliminate non-condensable gas production. Further development in this field will likely yield best-practice scenarios for adapting ocean thermal technologies to the authors’ proposed carbon capture techniques. We also note that electricity generated by OTEC avoids emission of air pollutants and particulates typically associated with the burning of fossil fuels.