Complementary explanations:
The total "direct" IR energy transfer from the Earth surface to the outer space would increase by the technologies described in this PNAS article, *by the atmospheric window (8-13 µm)*. In fact “*Radiative cooling*” can help to cool down the Earth by several ways: a) complementary to the albedo modification effect of "white roofs", which works during daytime. “*Clear sky night radiative cooling*" is complementary and increases the amount of IR that leaves the Earth by the atmospheric window (8-13 µm) *during night time*. Recently efficient daytime (and night time) radiative cooling has been proposed by Stanford scientists (=> Rephaeli E, Raman A, Fan S (2013) Ultra-broadband photonic structures to *achieve high-performance daytime radiative cooling*. Nano Lett 13(4):1457–1461.) b) reducing the use of air conditioning, reducing urban heat island, saving energy and reducing CO2 emissions c) increasing the yield of power plants: if the cold source is 15° lower => the increase of Carnot efficiency enhances electricity production with the same amount of CO2 emissions (=> paper from Ming et al ) d) renewable energy production (=> the PNAS article by Capasso and other Harvard scientists, but this is only theoretical for the moment) e) etc. <https://lh5.googleusercontent.com/-BB7yCuyX1-M/Uyopxx8_s4I/AAAAAAAAABQ/t7Wrawwd5LA/s1600/Radiation+Budget+600px.JPG> Le mardi 18 mars 2014 21:01:38 UTC+1, R Kiesgen de_Richter a écrit : > > Dear Group, > > Renewable energy can be generated whenever heat flows from a hotter to a > colder body. One such flow is from the warm surface of Earth to cold outer > space, via infrared thermal radiation. Physicists at the Harvard School of > Engineering and Applied Sciences envision a device that would harvest > energy from Earth’s infrared emissions into outer space. Heated by the sun, > our planet is warm compared to the frigid vacuum beyond. Thanks to recent > technological advances, the researchers say, that heat imbalance could soon > be transformed into direct-current (DC) power, taking advantage of a vast > and untapped energy source. An emissive energy harvester (EEH) is a device > that can generate energy from emitting thermal radiation* into the clear > sky. * > This new paper pubished in PNAS > http://www.pnas.org/content/early/2014/02/26/1402036111.short. > <http://www.pnas.org/content/early/2014/02/26/1402036111.short>BYRNES, > Steven J., BLANCHARD, Romain, et CAPASSO, Federico. Harvesting renewable > energy from Earth’s mid-infrared emissions. *Proceedings of the National > Academy of Sciences*, 2014, p. 201402036. > > This technology and several others are also proposed in the following open > access paper http://dx.doi.org/10.1016/j.rser.2013.12.032 by Ming, T., > de_Richter, R., Liu, W., & Caillol, S. (2014). Fighting global warming by > climate engineering: Is the Earth radiation management and the solar > radiation management any option for fighting climate change?. *Renewable > and Sustainable Energy Reviews*, *31*, 792-834. > Regards > Renaud > > Le samedi 25 janvier 2014 00:18:52 UTC+1, R Kiesgen de_Richter a écrit : > > Dear All, >> >> In SRM strategies, high-albedo surfaces are proposed to reduce solar heat >> gains by reflecting an increased amount of solar energy. At ground level >> the “cool roofs” and surface albedo change strategies very well described >> by Alvia Gaskill (a former very important contributor to this group) seemed >> sometime ago very promising. >> >> A very complementary technique to cool the Earth could be a strategy >> using night sky cooling surfaces that can pump heat away by radiative >> cooling to the atmosphere and get rid of the heat directly into outer >> space. The longwave energy is removed directly by transmission through the >> atmospheric window. >> >> When protected from wind, by clear sky and dry weather, heat transfer >> from ground surface by IR radiation is much faster than air convection, so >> a net cooling of the ground can occur resulting in well above air >> temperatures. >> >> This can be used to store at night, cold water for the daily use of >> cooling buildings: >> >> http://www.fsec.ucf.edu/en/publications/pdf/fsec-cr-1771-08.pdf (short >> version), >> >> http://www.fsec.ucf.edu/en/Publications/pdf/FSEC-CR-1882-11.pdf (long >> version) >> >> Parker, D. S., Sherwin, J. R., Hermelink, A. H., & Center, F. S. E. >> (2008). NightCool: A Nocturnal Radiation Cooling Concept. *2008 ACEEE >> Summer Study on Energy Efficiency in Buildings*, 209-222. >> >> Don't you think that large scale development of similar technologies for >> night time can be quite complementary to the daytime “cool roofs, cool >> paints, cool coatings, cool pavements, cool roads…” strategies? >> >> >> >> In the Earth radiation budget diagram showing incoming solar radiation >> and earth outgoing IR radiation, can this type of heat transfer be >> assimilated to an increase of the “atmospheric window” pathway? >> > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
