This is not dissimilar to a wild idea I had about 30 years ago relating to how to freeze ice to generate, essentially, encapsulated freshwater icebergs, that one would tow to regions needing freshwater‹and there are some others thinking now about how to somehow use the very strong temperature gradient to cool the Arctic or spray water as snow onto East Antarctica or Greenland. I would note, however, that what gets coldest is the surface of thick sea ice (not the air) as it is radiating to space as a black body whereas air has very low radiative potential (i.e., a low water vapor concentration)--it coos down being in contact with ice and being able to radiate its heat to the ice, that then can radiate the energy to space.
Basically, analogous to an air conditioner, the sea water below is the evaporator and then there must be a condenser in the air or the sea ice‹as it runs, the system would transfer heat from the ocean water to, ultimately, space, bypassing the insulating effect of the sea ice. The key engineering challenge is to keep the system free of ice build-up. In the ocean, the water is just above freezing and gets cooled as it transfers heat to the evaporator‹to keep ice from forming, one would need a good flow so one extracts just a little heat from a lot of water rather than a lot of heat from a little water; that would take energy to accomplish unless there is a strong current. For the condenser, the air is well below freezing and the gas in the evaporator is likely at the temperature of the sea water, so it is not at all clear there is enough energy to keep this from getting covered by ice (from snowfall, etc.). Thus, indeed, if one can figure out how to get energy from the ocean through the ice (which tends to insulate the ocean from cooling) so the energy can be radiated to space, one would have a way to cool the planet down during winter (assuming the sky stays pretty clear). Given the area¹s remoteness and the cold temperatures, etc., figuring out the engineering is thus critical‹one would like something with no moving, that floats in the right orientation until getting frozen into the ice, preferably has no moving parts, etc.--figure that out and one should get a real prize. Best, Mike MacCracken On 5/3/09 5:31 AM, "Andrew Lockley" <andrew.lock...@gmail.com> wrote: > This idea links well into proposals for pumping seawater onto the arctic ice > pack. Energy to drive the pumps could come from the heat exchangers, but the > actual effect could be far more widespread as it would result in > radiative/evaporative cooling of sea water and further an ice-albedo feedback > due to more resilient ice. > > However, wind turbines are likely to be simpler and more efficient, and thus > deliver better cooling by dumping more cool water onto the bitterly cold ice. > > A > > 2009/5/3 dsw_s <ds...@yahoo.com> >> >> Just a brainstormy late-night idea -- >> >> The air above the arctic and southern oceans is colder than the water, >> especially during the long winter night. It is possible in principle >> (although probably not practical) to extract energy from this >> temperature difference, by putting a heat exchanger in the air and >> another in the water, and running a heat engine on the heat flux from >> water to air. If it did turn out to be feasible, it would be an >> energy source that cools the planet -- directly by putting heat where >> it will be radiated to space sooner, indirectly by increasing sea ice >> coverage, and maybe indirectly again by increasing upward heat >> transport through the atmosphere. >> > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
