I have read that some believe the majority of the "waste" heat is a product of blacktop roads, roofs, etc., which absorb a broad range of frequencies and re-radiate it at much lower frequency band. If that is the case(?), a simple white paint with correctly selected constituent elements, For Example-whitewash as specified in NASA specifications for painting shelters of temperature measuring thermometer; would reflect most of the incoming rays and not store them as blacktop roads and black roofs apparently do and re-radiate them as much lower frequencies. Thus, the white surface would send most of the heat back into space. As a test, just feel a car painted pure white and compare that to a black pointed car; but be careful on a bright, sunny day re burning of hand, especially in southern US or even closer to equator! However, paint selection would be subject to NOT making a slick surface on roads, that would be disastrous, especially in rainy conditions. Also,glare might prove very limiting.
> Date: Sat, 6 Jun 2009 09:08:23 -0700 > Subject: [Global Change: 3221] Re: Why not rooftops covered with infrared > LEDs? an abstract in IEEE suggested .... > From: [email protected] > To: [email protected] > > > I don't have the full paper either; perhaps someone reading here does > have IEEE access, or knows where this was discussed if it was. > > On the microcosm, the reason is to rapidly remove heat from a > spacecraft by radiating it away. The ISS uses big flat radiator > panels rather than a 'cooling laser' because they can afford the huge > surface area required -- on the global scale, to emit through the > atmosphere would require wavelength control. > > I suppose the same question applies to painting roofs white -- all the > energy of making and applying the paint or new roofing material could > be used differently too. > > Heat that's already at the infrared level is mostly waste now, hard to > scrape it up somehow into thermodynamically useful energy. Can a > range of infrared be captured and used to emit in an IR window band? > > Some infrared photovoltaic material is being worked on > http://www.google.com/search?q=infrared+photovoltaic > > > Maybe there'd be a way to use that kind of material to tune the > wavelength and re-emit IR in a window band. > > That's what led me to wonder about using roofing material rather than > giant lasers -- the roofs have to be replaced every few decades > anyhow, whether with bright white or with something that is bright in > one of the IR windows. > > Hey, it's science fiction -- the idea is to get rid of low-value heat > by getting it collected in a wavelength that will exit through "IR > window" bands. > > A 'rogue wave' material -- something that from time to time will > collect enough energy from all the lower waves around it into one > larger wave tuned for the IR window. Paint or roofing material that > glows or sparkles in IR window frequencies when it gets warm. > http://scholar.google.com/scholar?q=%22Nature+Materials%22++infrared+photovoltaic > > Of course the IR astronomers working in those windows would hate the > idea. > > Hell, the visible light astronomers are going to hate the idea, now > that I look into it. > > You've seen the huge blindingly bright LED billboards now going up > along freeways? > > Imagine what the advertisers are going to do with sprayable paint-on > LEDs (sigh). > http://www.nature.com/nmat/journal/v8/n6/abs/nmat2459.html > > > _________________________________________________________________ Insert movie times and more without leaving Hotmail®. http://windowslive.com/Tutorial/Hotmail/QuickAdd?ocid=TXT_TAGLM_WL_HM_Tutorial_QuickAdd_062009 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
