Homemade Thermopile

(snip)

think.

A fair estimate of max power out is half of open circuit voltage times half of short circuited current. Note that your amp meter may not be a good short at these low voltages.

So maybe .6V*.23A=0.14 watts out.

On a sunny day (Mon, 03 Dec 2007 10:49:16 -0500) it happened John Popelish wrote in :

think.

At a delta t from about 35 C I think.

It is enough for a mp3 player already :-) If one could mount it so the one side is outside in the sun, and the other inside, maybe 60 C delta t could be reached, enough for a small radio. For the given surface area of maybe 10x10cm exposed to the sun, that would be good. No heat sink fans on the sun side, any wind would cool it down. Maybe a transparent plastic windscreen. So in 1 square meter that would be 10 x 10 of these, so sat 100 x 240 mW, or 24 W. Would heat up inside too (was assuming it stays at 20C). Large heatsink inside :-), small computer fan.

Or heat it up with an RTG. I was thinking (terrorist surfacing), as all those spacecrafts are not really protected against hijacking, as soon as Spaceship1 can get out of the earth gravity well, there must be a whole lot of good satellite electronics, maybe even some nuclear reactors, that one can bring back to play with. It is possible the Chinese have already thought of this ... Heat the one side with an RTG :-), those other side in the ground water..... Well, you should not drink that water then.

think.

protected

there must

that one

Best regards, Spehro Pefhany

Don't forget that sunlight is free, but the material costs necessary to convert said sunlight to electricity will nail you every time.

Unless... you plant a coconut tree, and process the coconuts into ethanol... ;-)

If you live in some place where coconut trees grow, you can just drink the ethanol and forget about the electricity.

Best regards, Spehro Pefhany

this is interesting

martin

I think.

Yup. The "impedance match" from a typical peltier to sunlight will be very, very bad. A custom peltier, with a higher thermal resistance, might work a little better, but the electrical resistance would go up too, so it may be a losing battle.

Thermal conversion of sunlight to electricity is inherently inefficient, since the sun runs at about 6000 C and the density on the ground is only about a kilowatt per square meter. Contrast that to active surface of a water-wall steam boiler, where the flame temp is a lot lower (better match to pressurized water) and the power density is megawatts per sq meter.

John

On a sunny day (Mon, 03 Dec 2007 11:16:14 -0500) it happened Spehro Pefhany wrote in :

Sure, I mentioned the fan, do you know how hot a 1 m^2 square metal plate can become in the sun ;-)?

Here are some producta:

Run you radio on a cooking burner in the wild?

On a sunny day (Mon, 03 Dec 2007 16:07:42 GMT) it happened Jan Panteltje wrote in :

protected

there must

that one

This one is funny too:

US spy satellite loss of signal....... After trying all frequencies and procedures, the US does a radar check on the position of the sat. It is there, exactly where it is supposed to be. 'Unknown electronic failure' is cited as cause of the problem.. Ten years later, when the US finally gets an other shuttle up there, to take a look, they find it, the satellite is marked: 'Dummy, Made in China'.

What, and live without s.e.d.? Burn the witch, burn the witch!

Hey, if worst comes to worst w.r.t. global warming, we can always grow mangoes, oranges and coconuts in Alaska, Canada, Russia and Antarctica...

Michael

martin

On a sunny day (Mon, 03 Dec 2007 20:36:53 +0100) it happened Martin Griffith wrote in :

I like the Russian model :-)

IIRC somebody in Russia also did something with a cathode substance, emitting electrons when heated, do not remember what happened to that.

It depends on the radio, I suppose.

"CQ, CQ. Come in, Rangoon" ain't gonna work. ;-)

On a sunny day (Mon, 03 Dec 2007 11:57:21 -0800) it happened "Paul Hovnanian P.E." wrote in :

I bet it will power a satellite phone ;-)

ARRGH! Stupid brainfart mistake on my part. I *wish* I could get millivolts out of a junction!

(Hangs head in shame)

Yeah! Three little zeros. And what's a zero? Nothing!

(Still kicking myself over stupid brain fart. Maybe it's time to get into management...)

Here is an idea that might work with third-world tech:

Stick the cold side of the thermopile in a river. Heat the hot side with a big fresnel lens molded out of recycled glass.

Manual labor to keep the hot spot focused on the thermopile as the sun moves.

It isn't unlimited or free unless you can extract it with a system that has material, labor, and operational costs all equal to zero.

If you have free labor, have it flip burgers at McDonalds and buy electricity from your local power company with the paycheck it gets. You will get a LOT more energy from the same amount of labor.

I tried that, and noticed a rather large *lack* of energy on my part.

So I drank some more and didn't care.