I am for putting up solar cells on a roof structure over the cars, as is already being done in some locations. I would think it would be a much more efficient way to capture the energy and it would shield the cars from the heat, so reduce their air-conditioning requirement. Now, indeed, that might not work in potential high wind (i.e., hurricane) regions, but I would think it would work fine in the West.
I'd also note that hot asphalt is also radiating an awful lot of energy away--if it really had high conductivity, the surface would stay cooler. So, the hot layer must be fairly thin and since one gets energy out of a temperature gradient, one really wants the heat conducting tubes near the surface, necessitating structural strength. Not to mention that darkening the surface has meant a lower planetary albedo, by a bit here and there. I would think it would be much, much more efficient to use the high quality solar energy directly rather than taking it up after absorption, unless what you need is a lot of hot water for some industrial process or for supplying some large facility needing hot water (sport facilities for their showers, etc.) or heat energy (e.g., when living in a cold environment, but then snow would cover the ground. I would note Iceland as an interesting example of using heat energy in clever ways. The steam and boiling water from geothermal sources is first used to generate electricity, then piped 40 km or so to Reykjavik to heat homes and hot water, and then is piped under the roads to melt winter snow and ice as they really don't want to have to devote people to clearing roads as opposed to generating income for their country. The US Southwest has the reverse problem--it would benefit from a pipeline of cold, deep ocean water, if only the pumping cost were free. Mike MacCracken On 8/15/09 9:07 AM, "Alvia Gaskill" <[email protected]> wrote: > > The GeoBusters are hard at work this morning, what with cereal being used to > stop hurricanes and my entry into the transformational energy debate, the > White TARP (so-named to gather immediate grass roots or more likely > astroturf support from the angry > teapartybirtherdeathpanelprotesterswhoallseemtobewhitepeople). The White > TARP is to be distinguished from that other TARP which cost a lot of money > and the blue one I bought at Lowes recently. The White TARP stands for > Thermal Ambient Reduction Program. OK, doesn't roll off the tongue like > Toxic Asset Relief Program, but for now will do. > > Here is my proposition. Whitening or lightening of parking lot pavement to > reduce the urban heat island effect will be a generational project both > domestically and internationally. Placing heat exchangers under the asphalt > to recover IR for the purpose of heating water or some other use will be > very expensive and also a generational length project. > > It is also unclear which one of these would give us the biggest bang for the > buck near term to use an old military cliche. Most of the parking lot space > is not used for parking, but cars go in and out all day, so in effect it is > used and any alteration has to take that into consideration. But not all > parking lots are used all the time. Schools, churches, government buildings > and shopping malls during the off peak season (very off peak of late) all > have parking areas that remain unused during the summer months and weekends. > Even most commercial businesses are not open on Saturdays and Sundays so > there are many days in which these gray to black sufaces just soak up the > rays of the sun and re-emit them, heating the air, the ground and buildings. > > So is it a better idea to give energy tax credits or some other form of > compensation to groups like the ones mentioned above to cover their unused > parking spaces with a white plastic sheet during periods of non use than to > spend money trying to recover this heat energy from under the asphalt? > Remember the White TARP can be done immediately, so the benefits begin > today, not decades from now. > > Yes, this isn't as sexy as the proposal in question and Parking Lot Energy > Corp sounds a lot more official than White TARP, LLC. And there will > certainly be those who object, waving their "Leave My Parking Lot Alone" > signs and angrily confronting their members of congress at the parking lot > reform town halls. If 1000 square miles of parking lots are suitable for > this treatment and the plastic costs $0.03/SF, then the cost of the plastic > is around $800K per square mile or $300 for a 10,000 SF parking lot. > > Asphalt reading #1 taken at 8:15am under overcast skies showed a surface > temp of 79F and at 9am with partly sunny skies was already 90F. I'll be > taking readings throughout the day and will seek out a suitable parking lot > for the full scale experiment. I have several thousand SF of white plastic > lying around and this would be a good opportunity to use it. > > Alvia Gaskill, CEO > White TARP, LLC (formerly Environmental Reference Materials, Inc.--that > ought to confuse the creditors for a while!) > > > ----- Original Message ----- > From: "Alvia Gaskill" <[email protected]> > To: <[email protected]>; <[email protected]> > Sent: Friday, August 14, 2009 10:45 PM > Subject: Re: [geo] whatever you think of orbiting solar... > > >> I don't as it would have very limited applicability if any at all. Plus, >> if the surfaces are eventually whitened as is the goal of the LBNL >> initiative, that would reduce the effectiveness of such systems. I also >> doubt that sufficient energy can be captured to make it worthwhile, >> although the principle is the same as that of using molten salt to store >> heat from CSP for use during the overnight to produce steam. >> >> The maximum temperature would probably follow the same pattern as the >> heating of the atmosphere, peaking somewhere around 4-6pm in the summer >> and reaching a lowpoint just before dawn. So the number of hours that >> usable heat could be "extracted" is much less than 24 and by the time it >> has passed through the heat exchanger system, it may not add significantly >> to any water that is to be heated. It seems like a very complicated way >> to produce energy on the margin when there are other more readily >> available sources. >> >> There is a long history of using undergound pipes to heat or cool >> surfaces, e.g. football fields and hockey arenas, but none in the area of >> heat collection in this way. In the interest of furthering scientific >> knowledge, I will take the trusty IR non contact thermometer outside right >> now and get a parking lot/roadway reading and also some tomorrow during >> the daytime. The range for tomorrow is 67-85F, much less than Phoenix, but >> it should give an idea as to what to expect. >> >> Results: probably biased because it rained earlier and nature took away >> all that valuable waste heat energy, but the air temp is about 73F at >> 10:30pm EDT and the roads, parking lots and sidewalks (I believe in being >> thorough) ranged from 74-77, indicating some residual heat in the >> pavement, but not very much. >> >> The article and or video noted that only a small fraction of parking lots >> were actually used for parking, so instead of installing an expensive and >> problematic heat exchanger system, why not have some of the post real >> estate collapse serfs place a white tarp onto these urban hot plates >> during the daytime and remove them at night. Now that's a use of the tarp >> that even old John McCain could support for Arizona. >> >> >> ----- Original Message ----- >> From: "Andrew Revkin" <[email protected]> >> To: <[email protected]> >> Sent: Friday, August 14, 2009 9:32 PM >> Subject: [geo] whatever you think of orbiting solar... >> >> >>> >>> does anyone out there see heat harvesting from parking lots as >>> "transformational? >>> http://dotearth.blogs.nytimes.com/2009/08/14/energy-frontiers-space-solar-ho >>> t-lots/ >>> weigh in... >>> >>> >>> -- >>> Andrew C. Revkin >>> The New York Times / Environment >>> 620 Eighth Ave., NY, NY 10018 >>> Tel: 212-556-7326 Mob: 914-441-5556 >>> Fax: 509-357-0965 >>> http://www.nytimes.com/revkin >>> >>>>> >> > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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