From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: Useful Power from A Single Solar Cell
Date: Mon, 28 May 2007 14:29:22 -0400
Message-ID: <4h7m53llikervrio450satnu6pocr7vt5h@4ax.com>

On 28 May 2007 10:55:26 -0700, BobG <bobgardner@aol.com> wrote:

>One of those boosters and a Honeywell Thermopile that is used to keep
>pilot light valves open would charge your cellphone if you put the
>thermopile in the campfire.

A whole lot better is the common Peltier pile, operated as a Seebeck device.  A
typical pile such as used in thermoelectric coolers will generate about 12 volts at a
couple amps when subjected to the same temperature differential as it would be
generating if powered.

I built a 12 volt, approx 5 amp battery charger using several piles clustered around
a hunk of aluminum heated with a propane torch.  The other side of each pile was
connected to a LARGE heat sink.

It worked great in cooler weather, lesser great in warm.  The major limitation is the
indium solder used to build the pile.  It has a low melting point and thus limits the
hot side temperature to a couple hundred degrees.

If one had a cold heat sink, say a spring or deep lake, to cool the cold side, I
wonder how a Peltier pile would compare in efficiency to a run-of-the-mill solar
cell?  Guess I need to do the math sometime.

One of my round tuit projects is to equip my generator with some piles to see if I
can use waste heat to generate some more electricity in enough quantity to make it
worthwhile.  One of the tuits I need is a source of cheap piles.

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: Useful Power from A Single Solar Cell
Date: Tue, 29 May 2007 22:20:58 -0400
Message-ID: <cdnp53pnu7mvdick62b130da571l0nul4c@4ax.com>

On Mon, 28 May 2007 23:43:08 +0100, Mike <nospam@nospam.com> wrote:

>On Mon, 28 May 2007 14:29:22 -0400, Neon John <no@never.com> wrote:
>
>
>>One of my round tuit projects is to equip my generator with some piles to see if I
>>can use waste heat to generate some more electricity in enough quantity to make it
>>worthwhile.  One of the tuits I need is a source of cheap piles.
>
>The conversion efficiency of peltier modules is next to hopeless.

Probably right in there with PVs.  Some back-of-the-napkin figuring. My charger made
about 5 amps at 13.8 volts or 69 watts.  A propane torch makes about 2,000 BTU/hr or
about 585 watts.  69/585 = about 12%.  Hmmm, never done the numbers before.  It
actually IS pretty close to PVs.

>
>But in the homepower world there is no such thing as waste heat.
>Either dump it into a hot water tank or, if you have too much hot
>water, drive an absorption refrigerator.   Running generators, even on
>waste oil and not grabbing the last bit of energy from them isn't IMHO
>very green.

I don't give a flying fsk about that ritualized pagan gaia worship called "green".
I'm pretty much the polar opposite - I would say I'm red but that color already has
its own political baggage.  All I care about is convenience and cost.  If I'm camping
in my RV and I can snatch a little more power from the generator's waste heat doing a
nifty experiment then I'll go for it.

John