Half a croissant, on a plate, with a sign in front of it saying '50c'
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To produce low cost solar electricity
  [vote for,

Large fields of modular Fresnel reflectors concentrate sunbeams on semiconductors bitherm junction type for an efficient Seebeck-Peltier effect. The flat mirors follow the sun race.

to provide a permanent difference between both faces of the bitherm, let's cold water running in it. Cooling by porosity effect : evaporation keep the water fresh.

simi, Oct 29 2002

Peltier links stuff http://www.peltier-info.com/
and most everyone's forgotten Seebeck [lurch, Oct 04 2004]

The McDLT https://qph.fs.quor...23647a2b3046d9e1f67
It never actually looked like this. [Amos Kito, Oct 04 2004, last modified Apr 16 2021]

Power from waste heat http://www.hi-z.com/websit07.htm
Water cooled, note... [lurch, Oct 04 2004]

Aluminum Foil Deflector Beanie http://zapatopi.net/afdb.html
I nominate this as the unofficial halfbakery Halloween costume. [thumbwax, Oct 04 2004]


       Good thing you said what it does.
snarfyguy, Oct 29 2002

       Thats easy for you to say, simi....
briandamage, Oct 29 2002

       Great stuff. Let's call in [FarmerJohn]; he'd love to supply a clockwork mechanism to drive the mirrors, I'm sure.   

       This will certainly allow you to put a lot of heat onto the hot junctions. What temperature will the hot junctions tolerate? How are you planning to sink the heat from the cold side?
lurch, Oct 29 2002

       Anyone have any figures or estimates of the conversion efficiency of Seebeck-Peltier? How many Watts per gradient degree through a standard medium?
RayfordSteele, Oct 29 2002

       Hi-Z seems to get about 4.5 percent out of their high power stuff; 230C hot to 30C cold.
lurch, Oct 29 2002

       "How are you planning to sink the heat from the cold side?"   

       If being used to generate power (Seebeck) would there be a cold side?
bristolz, Oct 30 2002

       Yes, it's the temperature differential between the pair of junctions that drives the thermoelectric effect. If both sides are hot, no heat flow, no current flow.
lurch, Oct 30 2002

       Ah, thanks, [lurch].   

       So, I'm a little confused.  Where does the cold side come from in the example described in this idea? The hot side comes from the focusing of sunlight upon the junction but . . . what cools the cold side, just the ambient air in the vicinity of the junction?
bristolz, Oct 30 2002

       There was an invention called the "McDLT" [link], where the hot side stayed hot and the cold side stayed cold. I don't know how they did it.
Amos Kito, Oct 30 2002

       The cold side could just be a giant heatsink (as it is in a computer system). I find it hard to believe this would be more efficient or cheaper than just heating water to make steam, though.
phoenix, Oct 30 2002

       I noticed that someone has built an exhaust system for a diesel truck that pulls about a kilowatt out of the waste heat. Allows disconnection of the alternator, and a 3 to 5 hp. increase in available engine power.
lurch, Oct 30 2002

       [lurch]: Interesting stuff. Got a link for that by chance?
half, Oct 30 2002

       To provide a permanent difference between both faces of the bitherm, let's cold water running in it. Cooling by porosity effect : evaporation keep the water fresh.
simi, Oct 30 2002

       The idea comes after I saw these 2 sites :   


simi, Oct 30 2002

       one more site :   


       but necessary to read a little bit french : doesn't matter anyway!   

       don't forget that we have to prevent another nuclear disaster, anywhere.
simi, Oct 30 2002

       [simi] - please use the [links] button above for adding URLs.   

       The cost figures given in those links (if my very poor French is not leading me astray) are substantially lower than anyplace I've found listing prices. By a factor of 6 or more.
lurch, Oct 31 2002

       ok, lurch,   

       To continue, let's think about the possibility to produce electricity 24h/24. To produce well, the calopile need 60°Celsuis delta. Is it possible to imagine a time lag in the system?
simi, Nov 03 2002

       If you heated enough mass during the day to store and radiate heat through the night?
bristolz, Nov 03 2002

       I don't think 4.5 percent beats a simple mirror-focused thermal engine, at any rate.   

       [Amos], it was made out of styrofoam, which was an improvement over typical McDonald's food.   

       [simi], to introduce a time lag, you'd need some sort of storage / collection system, which is easy enough to do with a hot water tank of some kind. But once you introduce that, you're just a step or two away from a steam engine.
RayfordSteele, Nov 03 2002

       [IronRay] - you're right, steam engines will definitely beat this for efficiency. But you need to have someone knowledgeable occaisionally "love 'em and lube 'em", or they won't continue doing it for long periods. I would like to see this set up as something you can ignore the heck out of without appreciable loss.   

       [simi] - // need 60°Celsuis delta // Ok, I went back and did some more French. Aachk! ptooy! Anyway, when I got to // converted to electricity with an efficiency approaching 100% // I threw up my hands. WIBNI, magic, hot air (not solar heated, either). Maybe this is satire, and I'm just not translating it well; sorry.
lurch, Nov 03 2002

       [lurch], "converted to electricity with an efficiency approaching 100%" not possible you said : maybe if the cold water begining hot is used as so, for another purpose... central heating or something like that for exemple.   

       [bristolz], [RayfordSteel], about lag time, solution is to use a sort of material dalaying action, with sandwich of diodes, for exemple, to increase the potential power. As soon as the temperature is falling (during night), current goes out. The question is : does this combinated material exist and at low price?
simi, Nov 04 2002

       Ahh... yeah. With a 60C delta you can certainly convert the waste heat into waste heat with pretty close to 100% efficiency, and allow Peltier and Seebeck to get back to playing with their dissimilar metallic toys. Didn't think that was what the idea was about, though.
lurch, Nov 04 2002

       Yes, makes a doable heat engine.
If the "calopile" was reality, it still would need a bit of wrangling to keep the heat from vaporizing its 0.0009 grams of snake oil.
WIBNI. 'bye.
lurch, Nov 05 2002

       [lurch] WIBNI : what is that? a new NIMBY?
simi, Nov 06 2002

       That's "Wouldn't It Be Nice If"; in other words, wishful thinking with no backing in reality. Please refer to the [help] link above on the left.   

       Note that WIBNI is often a call for deletion of the idea. I am not doing that. I like the idea; it's just this so-called "calopile" that appears to be fraudulent.
lurch, Nov 06 2002

       As mentioned before: use the [link] button for links. Please!   

       This looks better. There's been some good work done in this by CERN, Sandia labs, and others. The one drawback I see is that a lot of it is optimization - your hot side needs to be at a very controlled temperature. This is a good fit with, for example, a waste heat stream from a glass manufacturing operation - a precise temperature output is just a side effect of the process. At the mercy of random cloudiness, you either lose a lot of efficiency or simplicity.   

       Speaking of Sandia Labs - someone from there told me that they tested regular solar cells at over 600 suns, with adequate (read "lots and lots of") heatsinking. That could also work in this format...
lurch, Nov 08 2002

       what if you sandwich a layer of peltiers between a solar-heated road, and a network of water/sewer pipes below... a problem i foresee is that the road would be cold at night...
LoneRifle, Mar 10 2003

       [what if you sandwich a layer of peltiers between a solar-heated road, and a network of water/sewer pipes below... a problem i foresee is that the road would be cold at night...]   

       You'd waste a lot of money for very little gain.   

       Have you seen how much peltiers cost???
FloridaManatee, Mar 11 2003

       erm.... yea..... didn't realise.... sorry....
LoneRifle, Mar 14 2003

       [lurch] Neat link for the thermal-electric generator. One could possibly put one on an actual diesel generator, and create a pseudo-cogeneration generator.
rapid transit, May 17 2003

       You guys may be thinking about this backward. Why do any work? Inthe north we have 0'c temps outside and delta 90' temps inside 4-6 months of the year. You don't need to find temp differentials, only a super-cheap seebeck and cheap wires. Like the tin chimney in your house has the heat delta and one side of the conductor. See? BTW, these peltiers were standard equipment on furnaces for many years, running the electric thermostat and I hear the heat regulation too. They're still working 50 years after being forgotten. That's cost-savings right there.
TheSimpleton, Dec 10 2003

       You may need water cooling. That thing could get hot enough to melt the solder holding the metal junctions in place. Inside there are many junctions of dissimilar metals. They are soldered together meaning that too much heat may be bad for cheaper versions of the device.
travbm, Nov 01 2015


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