I have just looked at http://www.dself.dsl.pipex.com/MUSEU...moelectric.htm
and wondered why this technology seems to have died a death except for measuring instruments and a small niche market.

Trevor Bayliss (SP?) made a fortune by marketing a wind up radio for use by poor Africans.

Now to me a thermopile would be much more versatile, as long as you have a source of heat (cooking fire) you can generate electricity that you could use for lighting, for example LEDs would not use much power and would last longer than incandescent bulbs not to mention being more energy efficient.

I wonder what the practical limits would be? How about a Solar heated thermopile generating power setup, that would charge batteries during the day for use later at night.

One of the great advantages in my mind is that all the power generating "stuff" is solid state.

Just my 2p worth.

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Rick...

Science and sound engineering will always prevail in the end
"for nature cannot be fooled" [Feynman]

 

Do you know what the metal prices are today???

it's simply to expensive to make one and generate just a few volts at a low current

also if you would not supply the heat from solar than i think cost wise this would be more expensive to run than other forms of energie transitions

many things die not because of they are not good (personaly i think this one has a poor efficiency) but from it not being able to be comercialy intressting

Robert-Jan

 

Thermopiles (the kind made specifically to produce energy rather than a voltage) are very expensive and you need a lot of them (regular temperature measurement thermopiles are already expensive) and are VERY inefficient but VERY reliable and compact. Their abysmally low efficiency also means you need a MAJOR heat source for them to produce any "useable" power.

Their expense also means you can't build a lot of them to capture heat over a wide area so you need a very intense heat source to make maximum use of the small amount of thermopiles you do have. To put it into perspective, fossil fuel heat sources are not intensive enough to warrant the use of thermopiles. You need nuclear fuel which is even rarer, expensive, dangerous, and restricted.

Their only advantages are compactness and reliability- definately not cost or efficiency. So they are only really used for one thing: space probes that are meant to travel beyond the solar system:
http://en.wikipedia.org/wiki/Radiois...tric_generator

 

Yes, But....

If they could use a kerosene lamp to power a radio back in the 50s, http://www.dself.dsl.pipex.com/MUSEU...lectric.htm#rl
surely we could do better today?

__________________
Rick...

Science and sound engineering will always prevail in the end
"for nature cannot be fooled" [Feynman]

 

Depends if you believe that website or not!

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Just found
http://cgi.ebay.com/Thermoelectric-g...6.c0.m14.l1317

If it wasn't so expensive, I'd be very tempted

__________________
Rick...

Science and sound engineering will always prevail in the end
"for nature cannot be fooled" [Feynman]

 

Ah Ha,
Somebody is already looking into it
http://www.triz-journal.com/archives...01/a/index.htm

__________________
Rick...

Science and sound engineering will always prevail in the end
"for nature cannot be fooled" [Feynman]

 

Back then they would've used a crystal radio which didn't require a power supply other than the transmitter.

__________________
I also post at the following sites:
http://www.stop-microsoft.org http://www.heated-debates.com
Screen name: Aloone_Jonez
And http://www.silicontronics.com, same screen name as here.

 

Well, the spec sheet for this unit http://www.hi-z.com/hz20.php says...

Properties of the 13 Watt Module, HZ-14
Physical Properties Value Tolerance
Width & Length 2.95" (7.5 cm) ±0.01 (0.25)
Thickness
(Special Order) 0.2" (0.508) ±0.01 (0.25)
±0.002 (0.05)
Weight 115 grams ±3 grams
Compressive Yield Stress 10 ksi (70 MPa) minimum
Number of active couples 71 couples ----
Thermal Properties
Design Hot Side Temperature 230°C (450°F) ±10 (20)
Design Cold Side Temperature 30°C (85°F) ±5 (10)
Maximum Continuous Temperature 250°C (480°F) ----
Minimum Continuous Temperature none ----
Maximum Intermittent Temperature 400°C (750°F) ----
Thermal Conductivity* 0.024 W/cm*K +0.001
Heat Flux* 9.54 W/sqcm ±0.5
Electrical Properties (as a generator)*
Power** 19 Watts minimum
Load Voltage 2.38 Volts ±0.1
Internal Resistance 0.3 Ohm ±0.05
Current 8 Amps ±1
Open Circuit Voltage 5.0 Volts ±0.3
Efficiency 4.5 % minimum

* At Design Temperatures
** At Matched Load, refer to the graphs for properties at various operating temperatures and conditions.




Again, if they weren't so expensive at $209 each, I'd get some to play with

Lousy efficiency though

__________________
Rick...

Science and sound engineering will always prevail in the end
"for nature cannot be fooled" [Feynman]

 

The wikipedia has a nice article about radioisotope thermoelectric generators (RTG),
about halfway down it talks of stirling cycle engines coupled to alternators achieving better results than thermopiles with a given heat source. With plenty of info on the web about DIY stirling cycle engines it could make for an interesting project.

__________________
It may seem like a good idea at the time , but never stir your cold coffee with a soldering iron.

 

Actually they're not very reliable under a lot of circumstances.

They degrade at elevated temps- unfortunately, the highest output comes at the highest temps. The type capable of producing significant power- essentially just the Peltier devices on the market used in reverse- don't come in a variety of temp ranges.

They don't like rapid thermal cycling or mechanical stress. The thermal expansion can cause delamination.

So really you need:
A heat source that never goes over say 450F, but can't be much under 450F either or it loses effectiveness. A campfire cannot do this.

A heat source that does not change temp rapidly. A car engine is a problem here.

A cold sink capable of staying cold despite the high rate of thermal leakage coming through that device. So yeah it's like 4.5% efficient there, and I believe what that means is to get 19W out then you're having to flow 400W over to the cold side through the device. Wow... how you gonna maintain junction temp at 85F with 400W of heat? Probably can't. It'll live just fine if the junction temp rises to say 160F, but that's only 79% of the original temp differential so it costs you 21% of your output.

Heatsink costs are very high. And you still need an abundant, free heat source that can deliver 400W at close to 450F but not over 450F.

So looking at this again, if you have to power a radio out in the field or some LEDs, you'd need a propane heater where you can regulate the flame, a source of propane, you need a massive heatsink, and preferrably a water cooling system. All for... what, 19W? I could carry a lot of batteries for that weight and volume, maybe even a small generator.

It is neat though... silent power generation. The ability to generate output from temp differentials alone with low quality heat. Neat. But neatness aside, the numbers present problems in terms of practicality.

__________________
I thought what I'd do was I'd pretend I was one of those deaf-mutes.

 

(Nigal)

I was listening to a radio program the other day and they were very serious about using the water storage and pumps to pump the water back into a lake to be used later when needed.


A Thermopile seems to corrode to quickly and will breakdown faster when comparing it as to a solar cell or wind generators.




kv

__________________
Truthiness Monkeys : Obedience, Ignorance, Fear.

 

I just discovered that the Russians had used "Nuclear Lighthouses"
http://www.bellona.no/bellona.org/en...feration/28067
Gosh!!! is that dangerous or what? and the report is 5 years old!!

I think I will stick to Solar, thanks....

Killivolt, have a look at
http://en.wikipedia.org/wiki/Pumped-...droelectricity

__________________
Rick...

Science and sound engineering will always prevail in the end
"for nature cannot be fooled" [Feynman]

 

It's been used for years and years, it's VERY practical, I posted the website for one a few weeks back - in fact one I went round it a number of years ago, a truely impressive place.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

I didn't want to look up that (Post) But I remembered it. I wasn't really thinking the water storage thing was all that practical at the time.

But, now the idea is really getting into my head. And it is very practical.

Thanks.

Out where I live we had a lake that flooded everyone. So, they put in these expensive powerful pumps. Get this ........ our legislature at work.

They used them and it worked they pumped out some water and after that they were never used again. Worse still the years following we have been in a draught.

Go figure.

I don't know if they can pump up a hill or if they still have them.


kv

__________________
Truthiness Monkeys : Obedience, Ignorance, Fear.