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Triple-action solar power

Get energy from heat and *lack* of heat.
  [vote for,

This idea is for large solar panels on the roof of a building, each covering a shallow reservoir of water (maybe mercury would be better). As the panel heats up with increasing exposure to sunlight, the water or mercury heats up, expanding and lifting the panel, which is connected to a generator, it powers it with the lifting motion. When the heat dissipates, the water or mercury contracts again and the panel drops, this motion also turning the generator.

Not much energy, perhaps, but it'll supplement the energy already supplied by the solar panel itself.

21 Quest, Nov 21 2006

solar tower http://www.enviromi...ject/technology.htm
similar idea [bleh, Nov 21 2006]

Thermohydraulic Aiming http://www.solarser...ages/tha_skizze.gif
Expansion not used for power directly, but for more efficiency [loonquawl, Jan 26 2009]


       Too much resources to get //Not much energy// out of it. Solar panels are meant to be environmentally friendly.. and you're suggesting mercury?
twitch, Nov 21 2006

       Mercury as a possible substitute for water.
21 Quest, Nov 21 2006

       And as a generator of nice, health-giving mercury vapour.
angel, Nov 21 2006

       Ok, maybe mercury isn't a good idea. That's why I first suggested water, after all. Is there an environmentally liquid that expands better than water with heat?
21 Quest, Nov 21 2006


       Better, but still not much energy there.

       EDIT: Gas as in the state of matter, not the automotive fuel.
Texticle, Nov 21 2006

       I got the gas reference. I don't want petroleum pouring through my cieling.
21 Quest, Nov 21 2006

       this is kind of similar to the solar tower they're building in australa. they built a prototype in spain, but the thng was friggin huge, and it only put out 50MW of power.

       they used a large hollow disc (like a mile wide) to heat the air inside it and make it travel up a mile high tower driving turbines. ill try to find a link.

       edit: dimensions are wrong, see lower post.
bleh, Nov 21 2006

       Whoa. That's one big hamster they built there.
Texticle, Nov 21 2006

       This could be done using ammonia as long as there is decent heat dissipation at night, use a sealed container and the gas to liquid cycle, kind of a giant refrigerator.
pydor, Nov 21 2006

       Um, [Bleh] let me get this right. You are suggesting that "they" built a mile-high structure in spain? Did they run it up the side of a mountain, or did they just slip in the whole "Tallest Building In The World By A Factor Of 3" without telling anybody?

       Link please.
Custardguts, Nov 22 2006

       (sp) MW means megawatts (1,000,000 Watts); mW means milliwatts (0.001 Watts)
csea, Nov 22 2006

       the prototype in spain was smaller as prototypes often are. Dimensions are given at wikipeda. it ran for seven years and is well documented on both envromssion's site and it appears on wikipedia. there are pictures on the Enviromisson site linked under the prototype tab.

       [csea] fixed the MW, thanks

       after reading my previous post, i see the confusion. the proposed one had different dimensions that i rememered also (damn memory <slap>). to get the proposed 200MW it will need to be 7km wide and 1 km tall.
bleh, Nov 22 2006

       I think this would look pretty cool, kinda like when you breathe in and out, your chest rises and falls. Energy gain aside, it would be awesome to see a roof-full of independently rising and falling panels, not *using* any cost energy to make it happen.
21 Quest, Nov 22 2006

       200MW? Ha! I stand by my earlier comment.
Texticle, Nov 22 2006

       Yeah, 200 Megs isn't a great deal for the largest an possibly most technically challengine single construction job in history.

       <gets on high horse>

       Is this system prefferable than that a field (of far cheaper) solar pannels either photovoltaic or steam generating???? - Choose your selection criteria: purchase cost, maintenance cost, specific output (output per square metre of footprint), system reliability (one big artefact means a single problem can completely shut off the suply, whereas a field of panels could be arranged in a redundant network that is very robust for individual system failures).

       I don't mean to be a doubting thomas, but I really have my reservations about devices such as this. A quick back of the envelope calculation says this device should get roughly 5 watts per square metre, given 200MW and 7km diameter. That's not a particularly impressive return, not for a structure with a footprint of 38 square kilometers (nearly 4000 hectrares), and is 1 kilometre high. That's just friggin rediculous in my book, and as weak as they are, I can't imagine you can't do better with a field of photovoltaic cells, in terms of power-per footprint, investment cost, maintenance costs, etc.

Custardguts, Nov 22 2006

       [Custardguts] Can you combine this halfbaked idea with fully baked idea of concentrating collectors (equivalent capacity) & recalculate how much would be the reduction in required area compared to 4000 hectares !
vedarshi, Nov 23 2006

Custardguts, Nov 23 2006


       Sorry [21] me matey, didn't mean to pirate the thread and all that. Bloody Landlubbers.

Custardguts, Nov 23 2006

       //I think this would look pretty cool, kinda like when you breathe in and out, your chest rises and falls. Energy gain aside, it would be awesome to see a roof-full of independently rising and falling panels, not *using* any cost energy to make it happen.//

       I agree. for asthetic purposes, it would be cool, but wouldnt it be too slow to really see it happening? maybe use a sterling engine to get the 'breathing' roof thing. panels on the ceilng will have a temperature differential from ones placed in the house. They'll work fast in one way durng the summer (hot out side, cool inside), slow during fall(temps near the same), reverse direction during winter (Cold outside, warm inside) , then slow again in spring(near the same again) before reversing again in summer. Just have the piston drive a diaphram on each panel. that would be cool.

       lets forget the solar tower thing here guys, that is a separate (and baked) idea i thought was kind of similar. not really what [21] is talking about.

       didnt mean to get this off on a tangent, sorry [21].
bleh, Nov 24 2006

       Expansion of gas would be by same factor as rise in temperature (if measured in Kelvin, e.g from absolute zero), so heating from 270K (~0C) by factor 1.2 to ~320K (~50C) would increase the volume of gas, or pressure) by a fifth... The power of expanding substances is used to better aim solar panels at the sun, though, thereby increasing efficiency. [Link]
loonquawl, Jan 26 2009

       It depends on what pressures you work with (higher pressure also increases heat transfer). In this case the panel would need to be sprung to pull it shut. If the panel was 1m x 1m x 10cm, temperature range is 280-308K (10-38C) and starting pressure = 10atm (roughly 145 psi), the heated pressure would be 11atm capable of lifting an extra 1kg/cm2 (I've assumed 1atm = 1kg/cm2, it's actually 14.69psi and 14.22 psi). The panel would therefore lift over 10 tonnes for 1cm which is energy of 1KJ per day or enough to run a 100W bulb for 10 seconds.

       If it was at SCUBA tank pressures you could run your light bulb for over 3 minutes.

       I can't be bothered getting into how much heating energy would be available or what the heat transfer efficiency would be, I'm sure I've made a mistake in the calculations I've just done.
marklar, Jan 26 2009


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