Parking is already possible under CSP troughs. CSP is slightly more expensive than other forms of renewables but is is very simple, non-intermittent and hugely scalable. The aircon point is a good one, and it applies especially in malls, etc where cars have just enough time to get really hot. There is a utility benefit to this too, which will help offset the cost.
http://en.wikipedia.org/wiki/Concentrating_solar_power If you wanted a material that changes thermal absorption and emission then you could use frosted glass. It's pretty strong, so you could use if for a roof or car park. When it's dry, it's white, and when it's wet it's the same colour as what's behind it. Probably not cheap, but then neither would LCD be. A 2009/8/15 Stephen Salter <[email protected]> > > Hi All > > What you need is a material which is reflective on hot days but black on > hot nights and then changes to the opposite on cold days and nights as > a result of a small change of voltage. This ought to be easy for the > liquid crystal guys. But if they cannot do it we could look at pumping > different coloured liquids into the gap between two corrugated sheets of > polythene. > > Stephen > > Emeritus Professor of Engineering Design > School of Engineering and Electronics > University of Edinburgh > Mayfield Road > Edinburgh EH9 3JL > Scotland > tel +44 131 650 5704 > fax +44 131 650 5702 > Mobile 07795 203 195 > [email protected] > http://www.see.ed.ac.uk/~shs > > > > Mike MacCracken wrote: > > 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 > >>>> > >>>> > >> > > > > > > > > > > > > > > > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
