The PowerPot

[EZO]

I came across an interesting Kickstarter project today. The PowerPot, a thermoelectric generator in the form of a small cooking pot --- 4.5" x 5" (7" x 5" with lid). It can produce up to 5 Watts (~1A at ~5V) Has a USB A standard charging port, solid-state environmentally-hardened power circuit (regulator) and a fire-resistant cable and connector. A 10W model is available with a 15W in the works. It can charge or run cell phones, GPS, radios and other similar powered devices. Among other things their video on Kickstarter shows the device powering a Li-ion battery charger holding two 18650s and two 14500s. It is basically a backpacking product with interesting potential for emergency use and for use by people without electricity in developing nations. This thing ain't cheap but looks very interesting, assuming it works as advertised.

I wasn't exactly sure if it was ok to link directly to Kickstarter from CPF but after some searching I see a quite number of threads linking to Kickstarter proposals so I will go ahead and do so here. http://www.kickstarter.com/projects/1203647021/the-powerpot Their introductory video at Kickstarter is probably the best way to explain what it's about but they have a couple of shorter videos on YouTube as well.

PLEASE! Read their Kickstarter proposal and get ALL the facts and watch their video before posting any comments here, OK?

 

[eh4]

I think it's a wonderful idea.
I'm working on something similar myself, if I can get a little ahead $-wise I'd love to pre-order for their kickstarter project. Buying materials and paying bills is my current preoccupation though.
I like their take on it better than the Biolite stove and previous teapot style designs, nice that they're working on larger capacity versions.

If you'd like to play with some Seebeck modules yourself, do a search for TEGpower
and for some plug and play voltage regulation check out dimensionengineering.

 

[eh4]

Hmmm, maybe you put some posters off by demanding that we do our reading first.

I'm tempted to talk about my application, and if I had a little more experience with this sort of thing I would -an I will in a while.
If I had to guess I'd say that the patent issues are mostly at the high tech side of things, for the aluminum pot makers, the teg unit makers, etc. For people turning them into practical power generators it'll be more a matter of "who can build a better bike." Or I hope so, I want to see lots of designs, and for the prices to come way down.
The way I want to build mine it's still a bit expensive.

 

[EZO]

Yeah, I checked out TEGpower after I found the Kickstarter PowerPot page. Interesting stuff. There are many interesting possibilities for this technology, especially considering how many things in our lives produce waste heat.
I particularly like the idea of using the heat from an automotive exhaust manifold or the idea of using thermoelectrics instead of photovoltaics in solar applications with a much smaller footprint. I primarily heat with wood and that too opens up some interesting uses for a PowerPot or other similar use of thermoelectrics.

 

[EZO]

Hmmm, maybe you put some posters off by demanding that we do our reading first.

I'm tempted to talk about my application, and if I had a little more experience with this sort of thing I would -an I will in a while.
If I had to guess I'd say that the patent issues are mostly at the high tech side of things, for the aluminum pot makers, the teg unit makers, etc. For people turning them into practical power generators it'll be more a matter of "who can build a better bike." Or I hope so, I want to see lots of designs, and for the prices to come way down.
The way I want to build mine it's still a bit expensive.

A few times here on CPF I've launched threads about new products or technologies under development that I hoped would lead to interesting discussions but instead some CPFers would immediately chime in with cynical, negative remarks without bothering to read my reference links, do any research or even stop to think a bit. Some folks just think they know better or are otherwise just very jaded. In each case the comments amounted to baiting and the threads would get shut down. My intention in asking people to read the Kickstarter page was an attempt to avoid that, so perhaps the lack of response is telling. In any event, I appreciate your comments eh4.

P.S. I too wish this technology was cheaper. Maybe the prices will come down eventually.

 

[eh4]

Ok, you are in a particularly good position to take advantage of the tech because in your application weight is a non issue.
A lot of the fancy shenanigans that the portable designers are having to deal with come down to weight/power/cost, but you could get some real reliable power going the heat transfer fluid-teg-coolant water route.
TEGpower's 200 watt unit looks really sweet, much too pricey for me.
They claim (depending on how they massaged the data) that for someone heating with wood to power TEG (running 24/7 in Alaska!? talk about waste heat!) vs solar power in Southern California, that you could figure about 1 to 6, with a 15watt TEG producing many watt hours as a 90watt solar panel.

I've found low power dc pumps designed for hot fluids with 5 year running life, so 5 of those (1 extra to account for a lemon) could last the life of a battery of TEG.
Also the newer LiFePO4 12V systems look really promising for long life.

 

[EZO]

The PowerPot seems like a good compromise regarding weight in a backpacking product in that you could travel with fewer batteries and backpackers need a cooking pot anyway. I like the way these guys have thought this through and also the ancillary products they are offering that create a comprehensive and useful product line with future potential for improvement.

I think for larger scale applications the technology is still too expensive to offer any reasonable payback window, so it seems like it's still in the "enthusiast" category. TEGpower seems to be an example of enthusiasts trying to bring this to market in a more practical way but they don't (yet?) have the scale to bring down the prices.

I need to think some more about how this could work with my wood stove. There are several possibilities. Again, the cost makes it less than practical but still very interesting.

 

[SilverFox]

Hello EZO,

Interesting concept, but for backpacking I think it is unpractical.

With wood stove heat in the middle of winter and in an automobile, things change and it may be of some use.

The backpacking issue has to do with the additional weight involved in carrying the unit and if you really plan to use it to charge battery packs you are going to have to carry additional fuel. My Jet Boil allows me to boil a liter of water in something like 2.5 minutes. The unit doesn't produce enough power to charge a cell in that period of time.

Now if you make camp at a hot springs with surrounding snow, that is different and you could probably manage to charge a battery pack.

It would be interesting to run a test to see how may 3 minute charging sessions it would take to actually amount to enough of a charge to do something with. After a few days you could probably get a GPS unit running again if you happened to let it run all the way down.

I would think that solar would be better for backpacking. You can put the panel on top of your back pack and end up charging over a longer period of time. If some of that time is in direct sunlight, the solar panel may come out ahead.

Still, it is interesting technology.

Tom

 

[EZO]

You make some good points Silverfox. It might depend somewhat on the particular type and length of backpacking or camping trip, I 'spose. For example, in their Kickstarter presentation, they show the unit operating with a candle and on a fire, so conceivably you could operate the thing for long periods of time without having to lug extra canisters of stove fuel. Taking a long burning candle along backpacking would be no big deal and not very heavy. They seem to be suggesting that it would be useful for cooking at night with the supplied LED strip or used for an evening of music and or battery charging running the thing off a campfire. (Personally, I've never been big on backpacking with a lot of electronics.) They say the Powerpot weighs half a pound so it is probably similar to other backpacking cooking pots. I don't know, maybe it's a camping product more than a true backpacker thing. Many years ago in my youth I used to backpack a lot in the Presidentials with a whole Sigg Tourist kit and a Primus stove. It was cutting edge in its day but was far heavier than a PowerPot and some of today's stove models.

Where I live, out in the middle of nowhere, in a rural area where we sometimes have lengthy power outages, I could definitely see this as useful for emergency purposes. Onetime, some years back during a big ice storm that took out the power and phone for a week I had to use the inverter in my truck to charge my cell phone when I could finally get out and head into town and a PowerPot would have been just the thing to use on the woodstove at home. I have an 8kW propane generator but that would be overkill for charging the phone.

In any event, I agree, it is interesting technology. It remains to be seen if it is really practical or just an expensive novelty. It might be both.

edit: P.S. I'll bet a can of Sterno would be a handy way to get extended power out of one of these.

 

[eh4]

My target weight is under 8 oz, delivering 5V at 1-2amps depending on whether it's being run casually or being actively managed. Material cost alone right now is over 80$... not good for a reasonable product but I'm going to work that out right after I meet drop-on-rock and power output targets.
It's really a project for my own personal use, but of course I'd Love to end up with a viable product.

Silverfox you've got a good point about solar, the advantage with thermo-electric is that as long as you can make fire you could generate electricity, no matter how many overcast days you had or how short the days are.
Also while I personally want a solar panel for passively charging while backpacking or boating, I can also imagine many circumstances where it wasn't at all practical to be charging while on the move, but where there was plenty of time each evening sitting by a fire.
If you're strictly cooking with gas then I don't see much advantage with TEG, but if you backpack with a light weight wood stove or are in areas that permit campfires then it's another matter entirely. High efficiency, light weight wood stoves are another interest of mine that dovetails with this project,
Biolite made an interesting design by basically upgrading the old Zip Stove by replacing the battery for it's self stoking fan with the teg unit... so you keep feeding twigs and bark and the teg keeps a fan running to presumably cool the heat fins before being directed into the fire, creating draft, burning hot, clean and smoke free... and surplus electricity is sent to a usb plug -but it looks like the power provided is pretty low. I might be wrong about that part but it's limited by how much cooling the air can accomplish.
Should be much better performance in cold weather of course.

I've been playing with designs during the winters (stove building season) that batch load and burn upside down, meaning that you load about a popcan sized load of dry hardwood twigs, ignite the wood from the top and it burns down over the course of about a half hour, followed by about another half hour of coals (good for simmering). When the burn is right there is no smoke.
Here's some pics snagged from the web to quickly explain it: https://www.google.com/search?ix=iea&q=inverted downdraft gassification&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=Du2AT4iTDIO4twehzuiqBg&biw=1022&bih=515&sei=IO2AT-iLB4eJtwf846iQBg

The downside with the top loading inverted gassification design is that it's a Batch load... putting more wood on top part way through the burn screws everything up and makes loads of smoke.
I'm leaning twards the rocket stove system now, which can be fed continuously.

 

[EZO]

That was a really interesting post eh4. Although I've been aware of these Peltier effect devices for a long time I hadn't really thought much about them but you've got me intrigued about the possibilities.

I'm curious to know what is the minimum heat required for decent performance with these thermoelectric modules? It's given me an interesting idea for a very simple, cheap, disposable, very long lasting, very light heat source for backpacking. Heck, it might even get Silverfox to reconsider. What about using one or two of those air activated HotHands packets? I use them occasionally when out snowshoeing or hunting and they get REALLY quite hot for a VERY long time. One or two of those under a PowerPot and conceivably you could get power all night long and longer and you wouldn't even need a stove. (although your design does sound very cool)

Perhap the heat differential wouldn't be great enough but from what I think I understand about this, it seems like this would work with a PowerPot or similar full of water.

 

[eh4]

EZO, I think that it would be worth trying with a boost converter for powering an led or two, for that matter if you didn't mind a cold spot on your body you could probably run an led or two from the difference between cool/cold air and body temp.
You could probably get some bright results with a boost converter and 5mm leds... might make a cool "perpetual" light.

The units that I'm playing with didn't come with much in the way of documentation but I have found nearly identical units that are very well documented: http://www.customthermoelectric.com/powergen/pdf/1261G-7L31-04CL_spec_sht.pdf

As you see from the graphs, you need some significant heat to start getting any meaningful Wattage. The units I'm playing with can get up near 300C and will be destroyed at 325C on the hot side and 125C on the cold side.

btw, no affiliation other than that I bought one; LVBoost from dimensionengineering really is a slick little tiny boost converter. Weighs 3.5g and can deliver 5V from input as low as .5V, screw adjustable. very cool little bug.

 

[EZO]

eh4, Thanks for your reply. The pdf you linked to was interesting and enlightening. Now I understand this a little better.

We don't really know what circuitry is used in the PowerPot regulator but I got the idea that one could use Hot Hands packs with a PowerPot after seeing the video in post #1 where the guy powers up a double LED strip by placing the PowerPot in the hot spring. Hot Hands can get up to around 130F which would likely be in the neighborhood and probably a bit hotter than the hot spring in the video. Of course, he's using snow on the cold side.

As previously mentioned, it's too bad these modules are so expensive. For someone like me they may be too dear for casual tinkering. On the other hand, I can see this could be a slippery slope and it wouldn't be the first time I've ended up hip deep in parts, materials and solder. If that happens, it will be all your fault! 🙂

 

[jasonck08]

Interesting concept. I've played around with TEC's in the past, made a drink cooler out of a CPU heatsink 60W TEC and an old ATX power supply shell. I've thought about using them to generate power, however most of the consumer grade TEC's use solder and once you get above the solder point, the TEC fails.

Also as far as I know these units rely on the temperature differential between the two sides of the TEC / Peltier device in order to generate power. So it would seem to me that the device would be less efficient when the water begins to boil, then when you put cold water in the pot and applied heat to the bottom.

 

[SilverFox]

Hello Eh4,

Wood heat brings a different perspective to this whole thing. An efficient wood stove would allow you to run the stove for an extended period of time and not need much of a wood supply to do so. Unfortunately some areas in do not allow wood fires. Still, the idea of using wood opens things up a little on this.

Tom

 

[SilverFox]

Hello EZO,

The idea of using a had warmer also opens things up a little on this. I have some that can be re-charged by putting them into hot water. With a temperature of around 50 C, I am not sure how much power would be produced, but the hand warmer lasts a long time. Re-charging is reasonably fast so minimal fuel would be used.

Tom

 

[SilverFox]

Hello Jasonck08,

You bring up an important aspect to this. The output is most likely highest when the cold and hot temperatures are steady state. Boiling water is dynamic and the temperatures change during the process. It would be interesting to see a typical output curve from boiling a pan of water.

Tom

 

[eh4]

Boiling/simmering water will at least give some regulation and could keep the unit from exceeding it's DOA temperature.
But think of the performance if you had a steady flow of cool water... the pdf graph of the purple line looks really nice to me.

SilverFox, I see that you are in Bellingham... I love your town, the Air and the Sound and the misty mountains around... Almost moved out there last Spring, still might some other year soon. I keep thinking about renting a shack with a good view and building a collapsible skin on frame kayak to reach the islands... Ehhh I lost critical mass, other stuff came up and can't really think about it this year, but I tell you when I flew back here to my bluegrass state I was looking down into the flatness and haze and thinking "what am I still doing here?".

Interesting concept. I've played around with TEC's in the past, made a drink cooler out of a CPU heatsink 60W TEC and an old ATX power supply shell. I've thought about using them to generate power, however most of the consumer grade TEC's use solder and once you get above the solder point, the TEC fails.

Also as far as I know these units rely on the temperature differential between the two sides of the TEC / Peltier device in order to generate power. So it would seem to me that the device would be less efficient when the water begins to boil, then when you put cold water in the pot and applied heat to the bottom.

Yep, the TECs are not optimized for energy production, but I have seen lots of 100 of them surplus for 300$ on ebay, was kinda thinking that there might be applications where quantity and cheapness could just plain outperform the hot rated pricey ones...

And you point out my main concern with cooking pot TEG systems, effective cooking at the cost of effective power production and vise versa.

EZO, if you do experiment and decide to get something from tegpower, consider the 15V module as it's an all around useful voltage and has aluminum sides to it, should be quite durable for messing with.
The little 5V units that I ordered are quite fragile, quite, quite. I'm pretty much broke these days myself and experiments are painful when costly, but I suppose it keeps your wits sharp... I've got far more sense than money these days, if I had too much dough it might be the other way around. ;-)

 

[EZO]

Hello EZO,

The idea of using a had warmer also opens things up a little on this. I have some that can be re-charged by putting them into hot water. With a temperature of around 50 C, I am not sure how much power would be produced, but the hand warmer lasts a long time. Re-charging is reasonably fast so minimal fuel would be used.

Tom

Based on the video of the product being used in the hot springs it seems we can infer that the device should work, at least for some simple battery free lighting using HotHands packets. The light used in the video appears to have (20) 5mm LEDs that seem to be glowing pretty well for daytime. Of course, he's got the pot full of snow, but then again, with HotHands you wouldn't be boiling water and plain cold water might do the trick. Also, one wouldn't necessarily need 20 LEDs for some basic lighting. If this would work, then you could use this for general lighting needs, even inside a tent. Interesting.

 

[EZO]

EZO, if you do experiment and decide to get something from tegpower, consider the 15V module as it's an all around useful voltage and has aluminum sides to it, should be quite durable for messing with.
The little 5V units that I ordered are quite fragile, quite, quite. I'm pretty much broke these days myself and experiments are painful when costly, but I suppose it keeps your wits sharp... I've got far more sense than money these days, if I had too much dough it might be the other way around. ;-)

Thanks eh4, your advice could save me the expense and heartache of buying something I would break in very short order. I've been poking around looking at things and learning more about these modules. Probably it will be awhile before I could dabble with this due to the cost. I'm up against some big expenses lately due to medical reasons and a major repair to my property from Tropical Storm Irene, so fun, interesting hobby projects must take a back seat for now. Still, exploring a subject and learning is free and then if I pursue this further in the future I can avoid some of the pitfalls!

The TEGpower website is really very interesting. I found their 25 Watt wood stove model intriguing. It is quite a contraption though but it addresses one of my questions regarding how to dissipate the heat from a wood stove to achieve the desired temperature differential.