Floating two-phase closed thermosyphons for cooling polar waters during winter

Two-phase closed thermosyphons (TSs) are passive devices used to transfer heat against gravity. Approximately 120,000 TSs are used along an oil pipeline in Alaska and about 20,000 along a 20 km long permafrost portion of the railway line of Qaidam–Muli in China. Currently, probably several million TSs are in use in permafrost regions of Canada, Russia (Siberia), China and the US (Alaska) during the winter months to extract heat from underground and cool it thanks to the colder air above.
TSs are made of a hermetically sealed tube partially charged with a two-phase working fluid. Warmer temperatures underground heat the liquid working fluid in the underground part of the TS, vaporizing it and the vapor rises to the top, where the above-ground portion of the TS is subjected to cold ambient air which cools the vapor and condenses the working fluid which falls back downward, repeating the evaporation-condensation cycle. In summer, the cycle ceases as the air temperature is above the soil temperature.
Using floating TSs in polar water currents instead of in soils will result in more efficient cooling processes due to better contact and heat transfer. Cooling down polar waters will help slowdown melting sea-ice. The number of floating TSs necessary to have a significant cooling effect will be discussed together with the advantages and drawbacks of this proposal. The presentation highlights the improvements that can be performed over existing TSs, as well as possible synergies during summer months with new radiative cooling technologies allowing longwave radiation to escape to outer space through the atmospheric window.