h a l f b a k e r yThis would work fine, except in terms of success.
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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.
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]
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Too much resources to get //Not much
energy// out of it. Solar panels are meant
to be environmentally friendly.. and you're
suggesting mercury? |
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Mercury as a possible substitute for water. |
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And as a generator of nice, health-giving mercury vapour. |
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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? |
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Better, but still not much energy there.
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EDIT: Gas as in the state of matter, not the automotive fuel. |
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I got the gas reference. I don't want petroleum pouring through my cieling. |
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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.
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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.
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edit: dimensions are wrong, see lower
post. |
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Whoa. That's one big hamster they built there. |
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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. |
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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?
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(sp) MW means megawatts (1,000,000 Watts);
mW means milliwatts (0.001 Watts) |
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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.
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[csea] fixed the MW, thanks
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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. |
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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. |
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200MW? Ha! I stand by my earlier comment. |
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Yeah, 200 Megs isn't a great deal for the largest an possibly most technically challengine single construction job in history.
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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).
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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.
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[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 ! |
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Sorry [21] me matey, didn't mean to pirate the thread and all that. Bloody Landlubbers.
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//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.//
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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.
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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.
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didnt mean to get this off on a tangent,
sorry [21]. |
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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] |
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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.
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If it was at SCUBA tank pressures you could run your light bulb for over 3 minutes.
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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. |
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