Homemade Thermopile

[Jan Panteltje]

I believe you can buy Peltier powered fans that work in stovepipes, so
the ice may not be necessary. ;-)

One note, the open voltage I measured still had the 12V fan parallel to it I think.
Probably true open voltage is even higher.

 

[John Popelish]

(snip)
One note, the open voltage I measured still had the 12V fan parallel to it I think.
Probably true open voltage is even higher.

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.

 

[Jan Panteltje]

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.

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.

 

[Spehro Pefhany]

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.

60°C? The Peltier will have a rather low thermal reistance because of
all those parallel junctions (over a thousand in a moderate size
unit). If you want 60K difference you might need to have a few square
foot mirror or lens, and it might take a fan to cool the other side to
near room temperature. Maybe you can use all the 'free' energy to run
the fan... say 12V at 100mA = 1.2W.

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.

Best regards,
Spehro Pefhany

 

[[email protected]]

THANKS FOR ALL YOUR IINPUT

To clarify the concept, what I am trying to do is see if there is a
low tech, relatively cheap method of utilizing the UNLIMITED
FREEenergy represented by the low-grade temperature differentials
between natural occurring sources like ambient air and ground water.

I know that thermopiles are not very efficient. But since the energy
is free and I am not looking to manufacture and sell anything (hence
the "homemade") the labor is free, the only cost consideration is the
material costs. If the material costs can be made low enough, a
viable alternative may be achievable even with very low efficiencies.

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... ;-)

M

 

[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... ;-)

M

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

 

[Martin Griffith]

At somewhat lower efficiency (past the halfway point IIRC) by now. Partly
due to the decay of the Pu238 (note it's not the more infamous Pu239 of
weapons fame, nor Pu244 or so of reactor grade fame), which is quite rapid.

The largest RTG NASA has sent up was on Cassini, IIRC. Remember people
were making a big stink about the 80-some odd pounds of plutonium on
launch?

Tim

this is interesting
http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html


martin

 

[John Larkin]

60°C? The Peltier will have a rather low thermal reistance because of
all those parallel junctions (over a thousand in a moderate size
unit). If you want 60K difference you might need to have a few square
foot mirror or lens, and it might take a fan to cool the other side to
near room temperature. Maybe you can use all the 'free' energy to run
the fan... say 12V at 100mA = 1.2W.

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

 

[Jan Panteltje]

60°C? The Peltier will have a rather low thermal reistance because of
all those parallel junctions (over a thousand in a moderate size
unit). If you want 60K difference you might need to have a few square
foot mirror or lens, and it might take a fan to cool the other side to
near room temperature. Maybe you can use all the 'free' energy to run
the fan... say 12V at 100mA = 1.2W.

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:
http://thermalforce.de/de/product/module/index.php?uid=e3dd64ceab0f0a1e49761a900d98fcde&ref=

Run you radio on a cooking burner in the wild?

 

[Jan Panteltje]

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.

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'.

 

[[email protected]]

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

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 Griffith]

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:
http://thermalforce.de/de/product/module/index.php?uid=e3dd64ceab0f0a1e49761a900d98fcde&ref=

Run you radio on a cooking burner in the wild?

http://www.dself.dsl.pipex.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm



martin

 

[Jan Panteltje]

http://www.dself.dsl.pipex.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm

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.

 

[Paul Hovnanian P.E.]

[snip]

Run you radio on a cooking burner in the wild?

It depends on the radio, I suppose.

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

 

[Jan Panteltje]

[snip]

Run you radio on a cooking burner in the wild?

It depends on the radio, I suppose.

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

I bet it will power a satellite phone ;-)

 

[Guy Macon]

Microvolts, actually.

John

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

(Hangs head in shame)

 

[Guy Macon]

What's three orders of magnitude between friends?

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...)

 

[Guy Macon]

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.

 

[Guy Macon]

To clarify the concept, what I am trying to do is see if there is a
low tech, relatively cheap method of utilizing the UNLIMITED
FREEenergy represented by the low-grade temperature differentials
between natural occurring sources like ambient air and ground water.

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.

the labor is free

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.

 

[Guy Macon]

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

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

So I drank some more and didn't care.