<div dir="ltr">Crispin:<br><br>Could you please give some idea of daily average and peak electric demand of some users, and corresponding locations, where TEGs can be viable substitutes for pico-PV or diesel/kerosene generators?<br><br>It would help to know the cost and quality of the requisite amount of biomass and the split between cooking and non-cooking requirements. <br><br>Why not just use the TEG for electric cooking via induction stoves? <br><br>Over the years I have found solid or liquid biofuels for small-scale electricity provision - own use or small grids for greenfield electrification - to be a waste of money or attention. Past failure is no guarantee of future failure, and biomass for grid feed-in or cogen is an established business line but even then for limited range of contexts.<br><br>Trees grow on land, need water and labor, and skills and finance. Renewability is mere puffery; nothing is strictly renewable, not even research grants. <br><br><br><br>Nikhil<br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><font face="georgia, serif">------------------------</font></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Thu, Jan 3, 2019 at 2:51 PM Crispin Pemberton-Pigott <<a href="mailto:crispinpigott@outlook.com">crispinpigott@outlook.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span>Dear Tony<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>I found in Singapore these units:<u></u><u></u></span></p>
<p class="MsoNormal"><span><a href="https://www.ebay.com/bhp/thermoelectric-generator" target="_blank">https://www.ebay.com/bhp/thermoelectric-generator</a><u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Look at the second item. Notice that it only goes to 150 C. That is a problem. Attached is one example with a 200 C upper temp limit. Watch that very carefully. It ha to do with the melting temp
of the solder used to connect the many modules in each one. Exceed that temperature just once, and it is over. Keeping them under 150 is difficult. However it is important to remember that the heat flow is dynamic: if you can pull a lot of heat away from the
TEG, you can put it against a surface that is considerably hotter than the rated limit. For example you can have a 350 degree heat source and a 150 degree rating, as long as the temperature inside the TEG is under 150, because you are pulling the heat out
at perhaps 40 C with water, for example.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>P&N has a <a href="https://www.alibaba.com/product-detail/Strong-durable-thermoelectric-electric-generator_1926529487.html?spm=a2700.7724857.normalList.6.3cd4229dRJBbf6" target="_blank">
unit</a> which claims to be 250 C but the caution at the bottom of the page is 225 or less. They have models with up to 2 amps output each. These are very high performance compared with what was available two years ago.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>But cut off that cooling momentarily and the TEG is fried. Look at the top photo
<a href="http://www.peltier-thermoelectriccooler.com/supplier-217741-teg-thermoelectric-generator" target="_blank">
here</a>. You can see little ladder-like structures between the plates. Each one is a separate TEG soldered to the plates.
<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Yes, they are coolers running backwards, but the low cost of the coolers makes it worth it., The difference is not much. The ones I used were 40mm square and 1 watt and $1.00. I found the identical
units for sale over the counter in Beijing for the same price so someone is banging them out in large numbers.
<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>I found that the high power density ones are far more expensive per Watt. Really not worth it.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>And always add an appropriate sized buck-booster so whatever the input is, the output is 5.1 VDC. Be careful of totally misleading wording in the ads.
<a href="https://www.ebay.com/itm/US-40-40MM-Thermoelectric-Power-Generator-Heatsink-Peltier-Module-TEC1-12V-60W-/163399216228" target="_blank">
This</a> is a cooler, not a generator. <a href="http://www.peltier-thermoelectriccooler.com/sale-9851547-peltier-module-teg-thermoelectric-generator-for-power-peltier-power-generator.html" target="_blank">
This</a> one is rated at 250 C on the hot side, 3 Watts. Plus they give proper performance curves.
<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Here is a test setup using a hot aluminum plate, three 50mm square 1 Watt TEGs, and a buck-booster connected to a single white LED:<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><img border="0" width="567" height="270" style="width: 5.9062in; height: 2.8125in;" id="gmail-m_-323934056546382341Picture_x0020_1" src="cid:168166399ef6917eb1"><span><u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>The light is on the end of a purple wire. The blue thing is the USB buck-booster that regulates the voltage to ne constantly at 5.1v with a current that varies with power available. It is a 600 ma
one so it is 3 W at 5.1 v.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Here is a photo of taken of a TJ4.0 stove with three TEGs sitting under a pot on the end of the heat exchanger. That location never heats up enough to damage the generator. The power running the
LED is 1 Watt (200 ma at 5.1 v) limited by the buck booster ($1) which was max 200 ma.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><img border="0" width="567" height="513" style="width: 5.9062in; height: 5.3437in;" id="gmail-m_-323934056546382341Picture_x0020_2" src="cid:168166399ef772f6c2"><span><u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>That is one HE-LED lighting up the CAU stove lab.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Pretty impressive. When giving that LED 3 Watts, it is too bright to be looked at directly. Oh, and you have to properly cool the LED or it overheats rapidly.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Regards<u></u><u></u></span></p>
<p class="MsoNormal"><span>Crispin<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Stoves <<a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a>>
<b>On Behalf Of </b>Tony Vovers<br>
<b>Sent:</b> Thursday, January 03, 2019 1:55 PM<br>
<b>To:</b> Discussion of biomass cooking stoves <<a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.org</a>><br>
<b>Subject:</b> [Stoves] TEG Thermoelectric Generator for stoves<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Dear Stover's<u></u><u></u></p>
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<p class="MsoNormal">We want to buy some TEG to use in school stove projects to demonstrate applications of biomass energy.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">Most of the online ones we have found seem to be TEC run backwards, low temp and look fragile.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal">Can anyone suggest a model/supplier to use for stove projects??<u></u><u></u></p>
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<div>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">We are in Indonesia but have friends in US or Australia who can bring some samples.<u></u><u></u></p>
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<p class="MsoNormal">Any suggestions??<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Our stoves will be typically kitchen sized cook stoves Rocket and TLUD designs.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<div>
<p class="MsoNormal">Many thanks<u></u><u></u></p>
</div>
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<p class="MsoNormal">TonyV<u></u><u></u></p>
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