thermoelectricity

backyard,

The efficiency is unfortunately very low--something like 3% IIRC. (We discussed this here a year or two back.) I've heard of thermoelectrics being used on a camp stove under a pot of water, to charge batteries, but that's about it.

Cheers

Phil Hobbs

That's about the only place I could see a thermoelectric being useful -- even then, careful measurement would probably show that you're reducing the heat available to boil the water.

Heat engines working off of the Rankine or Sterling cycles are the method of choice if you're looking to efficiently extract energy from a temperature difference.

the backyard,

I think they used them for electricity in some space missions. Wrap a bunch of TEC's around a warm nuclear pile, with the cold end sticking into space.

George H.

backyard,

Don't deep-space probes use plutonium heat sources and t/c voltage generators? I suppose efficiency is low.

I read a horrible story about some hunters, in the Ukrane in winter, who happened upon a gadget in the forest that was warm, left over from a defunct Soviet weather station.

John

zekfrivolous?

backyard,

I once stumbled upon a Peltier cooler manufacturer, which mentioned in their documentation that the Peltier element can be used to create electricity, but warned that the efficiently is going to be low. However, they mentioned that the efficiently is going to be very low, but some cells had been used on a natural gas pipeline to power some sensors.

It appears that in 1930's Peltier elements have been used to power a radio by the heat of an oil lamp in Siberia.

Apollo SNAP, Pioneer 10/11, Voyager, Galileo, Ulysses, Cassini.

The Eastern shores of the Baltic Sea is full of ex-Soviet lighthouses powered by RTGs :-(.

Paul

You get a pretty good differential just from the dark/sunny side.

greg

I somehow came up with that from my name.

Greg Szekeres

greg

Sure; the usual application is a radio receiver powered by a kerosene lamp (emergency light and radio both). The problem is that old materials were inefficient, newer materials are exotic and not easily handled (the best thermoelectric coefficients are from semiconductors).

Tunnel diodes and Ge transistors can operate comfortably with under 1V levels...

There are fans for wood stoves that use them. Here's one

Dood!

If it's a beta-emitter, aren't beta particles just fast electrons?

Howcome somebody hasn't tried capturing them directly? (or at least focus them and shoot bunches of them through a coil or something?)

Thanks, Rich

They'd be OK if anybody'd bothered to do periodic maintenance, wouldn't they?

Of course, you've got the institutionalized paranoia keeping people from properly recycling the spent fuel...

Thanks, Rich

Where do you get one? ;-)

Thanks! Rich

There have been direct beta batteries made. Unfortunately, they are thevenin equivalents of things like gigohms and hundreds of kilovolts. It's hard to build a 300 KV dc/dc converter, although some work has been done with tubes. Discharge devices, gaps or bending beams or such, can discharge high voltages into transformers.

Since betas have very low penetrating power, only the thin top surface of an emitter gets much out, and a fraction of that hits the cathode. A thermal converter can use the entire mass of the radioactive stuff.

John

not around uranus (or past Mars either!)

backyard,

Rally around the *thermal* neutrons!

Thanks for the info, but it kinda takes the wind out of the sails of my latest fantasy invention. ;-)

Cheers! Rich