Renewable Energy Questions/Discussion > Renewable Energy Q&A

Peltier units and Wood heaters

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DJ:

Am I missing something or is there some abstract reason or situation where Spending over $500 on a devise that generates 45W under ideal circumstances is justified for home use? 

Just buy a couple of used panels and You'd make loads more power even on overcast days.

Reading the info, stove has to be over 500F, 260 C for the thing to work.  I wonder how long that's going to take to heat the house, especially if it's a small off grid place, till the joint is so hot you have to open the windows or doors. From there on you are constantly keeping the fire hot and wasting wood in the process.  Probably spending more on fuel for the chainsaw and splitter than just going and buying fuel for a small generator that you can do a lot more with  and would be far more practical.

I have one of those cheap little 2 stroke generators that do 800W.  Thing runs all day on bugger all fuel, is quiet as a mouse and cost bugger all.  Rather get one of those and pay for the fuel if I was off grid and needed power than throw money away on one of those things.
I can use the genny in summer too.  Not about to go lighting hot wood fires and in a lot of places, may not be allowed anyway.

Things like this just make me shake my head.
Last thing I saw aimed at the same twits whom would buy something like this was a little Hydro Generator.  It was aimed at people who liked the outdoors to give them a source of power. You put this little propeller in a stream or creek and secure the other end and the thing makes power you can charge things with it like phones and flashlights etc. at .... a massive 4-5W.
This idiot thing won awards and and was featured in all sorts of magazines and articles like it was bred that sliced and toasted itself.

Do people never think about using these ridiculous things?  First, you have to find water, water running at the correct speed of course that you can get to easily. second, even when you do find the right water, You'd have to sit there all dam day for the thing to make enough power to charge the average phone.
I think that one was about $2-300 from memory.  As they say, one born every minute.  For way under $100 you can get foldable panel arrays that you can drape over a back pack as you walk along and they are rated up to 60W.  Again, even on a bad day or walking in bush are going to give you the same sort of power as the hydro thing and cost at least half the price.  In clear sunshine, no contest.

I do not understand how they even bother to offer things like this.  I'm sure some people buy them though which is even more a worry.

hiker1:
Yes just a interesting gizmo...just another in a world of gizmos......like the iPhone Im using for this..who would have thought what a phone would change into back in the 70s....

MadScientist267:
Radio shack sold a tiny cheesy solar cell and a little motor that was just strong enough to get out of its own way... in the 70s. It was 15 bucks as I recall, and served absolutely no "practical" purpose... Outrageously expensive in terms of per-watt, and I remember thinking (in addition to being told) that it would never be useful beyond a toy.

Or would it...

I for one was forever intrigued by the magic... and if I had to attribute any single "thing like this" to my interest in solar, that would be it. Many years later I put what it started (along with a whole bunch of other concepts) to the test with a Uhaul truck... and lived in it for over 2 years, full time. So much for useless.

So, I told you that to tell you this...

This isn't even to mention the *absolutely* practical value of things related to peltier and it's cousins... Without people looking into how these mysterious forces work, many an adventure wouldn't have been possible, say, in space. Big-G "RTG" for information on this not-exact but closely related "useless" technology...

Guess where it starts...

I'm not saying that the seebeck effect (what you're actually describing) is incredibly efficient; it's not. But neither is peltier as a cooling device, and yet I've proven for myself that they are indeed viable under the right circumstances, for more than trivial purposes.  Horses for courses type thing.

Is everything always practical? No. But this is how we learn how to do new things... "Playing" with principles and refining them into something actually useful. That said, I don't advocate building some massive seebeck device out of a bazillion peltier modules running "backwards"... in an attempt to run your house from a mega bonfire... But shooting things completely out of the air just because at present they're not "quite there" in terms of practicality, that's equally as bad.

... end rant lol

Steve

DJ:

--- Quote from: MadScientist267 on July 19, 2018, 04:20:00 pm ---
But shooting things completely out of the air just because at present they're not "quite there" in terms of practicality, that's equally as bad.

--- End quote ---

I do get what you are saying Steve but in this particular example I think it's different to the value of inspiration and thought to what you describe.

To me, this specific devise and the hydro one are nothing short of con jobs in that they purport to have a practical functionally they charge a premium price for but cannot deliver. they are taking advantage of that intreauge in the magic you had many years back and lies within a lot of us. I see a detrimental effect with these things in them being far more likely to turn people off creatively thinking about them than being inspired.

You buy the Hydro thing and then realise the thing is useless because the water you put it in is not flowing at the unusually high speed required.  You pay over 500 bux for something that you have to near cook yourself with and work at wasting firewood just to charge a small battery.
The end result is the though you wasted money and these things, Hydro/ peltiers don't work the way they are made out and are dismissed and leave a sense of disappoint as well.

The creators of these Priced to kill products know their shortcomings and their very narrow and impractical window of living up to the created hype. To me that makes them con men.
The fact the hydro thing won so many awards is just a bloody sad indication of how Gaa gaa the world has become about anything touted to be " Green" and how so many will turn a blind eye to the shortcomings of such products because they feel obligated to gush over and never criticise the green religion.
Again, to me this is detrimental rather than helpful.

What would be much better in my mind would be to be honest, admit the shortcomings and work on solutions so they did live up to the expectations created and be able to be used in a practical, everyday way.

There is still this ridiculous and often dishonest/ self serving attitude or excuse that things that are lacking need to be built so they can be learned from even if they do fail spectacularly. I have seen this applied to things like electric cars and many other things.
It's a complete crock of ship.
You don't need to build anything thse days to know what it's going to do, it can all be computer modelled.  If they can design things like aircraft from passenger airliners to cutting edge Fighter jets and the things take off and fly round without problem and go into production with virtually no modification, there isn't much else you need to build a bunch of to see how they will perform.

There is a big difference between something that's sold as a Toy which will inspire creative minds and some priced to kill gimmick who's one and only function is to remove money from peoples wallets under largely false pretences.

I too had one of those little solar cells driving a little motor you could put a fan on or a swirling coloured disk in one of the tandy ( radio Shack)  100 in one electronic kits.   :D

hiker1:
Electric bike..solar powered..small solar motor powers it....bought that I belive back in the 70s. ?  Love to bike so I've had that all these years.....😜

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