generating power with peltier cells - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: June 29, 2011, 11:51:40 am
content: I'm thinking of playing with some peltier cells and making electricity with them. Is this feasable ? what sort of generation do they have versus their power consumption as heaters/coolers.What is the max temperature you can heat a peltier to ?

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 29, 2011, 12:45:29 pm
content: Generally, the setup people think of is heating by the sun on one side and not heating the other. Typical efficiencies are very poor. Around 5%. You need to maintain a very cool second side to do much better than that. $/watt come out to about the same as solar, but you would need to get the surface very hot to generate some real power. So parabolic mirrors or lenses, etc.You will also find the voltage is very low, as compared to solar. Look at the Seebeck coefficient. It is typically uV/K. So you need a very large temperature difference to get any usable voltage. Although I'm not sure what the current levels are.

author: Simon
author_rank: Unknown
timestamp: June 29, 2011, 01:03:08 pm
content: I was thinking of a small wood furnace, solar just won't do it I realize that

author: ejeffrey
author_rank: Super Contributor
timestamp: June 29, 2011, 01:21:38 pm
content: I have seen this done successfully. The efficiency isn't great, but the application I saw was to use the heat from a small stove to run a circulation fan (basically a 120 mm computer case fan). The fan blew over the radiator on the 'cold' side of the peltier to help keep delta-T high to keep the generated power up.I think the maximum temperature is usually limited by the packaging -- especially contact wire insulation and solder. So you probably have to shop specifically for high temperature devices.

author: insurgent
author_rank: Regular Contributor
timestamp: June 29, 2011, 01:44:42 pm
content: I've been looking into thermoelectrics recently but am by no means an experts on the subject. From what I've seen, the Peltier devices can be used to generate electricity but will not last very long when used for that purpose.Apparently for power generation, you want use a thermoelectric generator (TEG) device that exploits the Seeback effect as opposed to the Peltier effect (they are very closely related effects). I'm not sure if there is a difference in efficiency between the two devices.If you just want to mess around and have Peliers lying around, I'd use them. If you desire to design a project that will last, you should probably look at the TEG's. There are some inexpensive ones on ebay in the $15-$20 range.

author: Simon
author_rank: Unknown
timestamp: June 29, 2011, 04:30:06 pm
content: there are some very cheap devices on ebay with "TEG" in the title but they only give specs for heating and cooling and nothing about power generating capabilities and limits

author: Zad
author_rank: Super Contributor
timestamp: June 29, 2011, 05:31:05 pm
content: From my experiments they seem to produce slightly less than bugger all power. The solder holding the elements in place tends to soften quite early and distort the array.

author: Simon
author_rank: Unknown
timestamp: June 29, 2011, 05:54:41 pm
content: I did read an essay about a commercial unit that cost over 1000 whatever (I think he was in Canada) and it was quite clever. As i've got wood to burn and potentially these things are cheap now I thought it would be interesting to have a play and see what i can come up with.

author: johnmx
author_rank: Frequent Contributor
timestamp: June 29, 2011, 06:53:01 pm
content: Read the LT Magazine of October 2011.All you need to know is there.I’m going to make this circuit. I already have all components, including the LTC3108 and several transformers from Coilcraft. All I need is time to design the PCB. But first I want to finish other projects.http://cds.linear.com/docs/LT%20Journal/LTJournal_V20N3_Oct10.pdfI recommend everyone to read the LT Magazines, now called LT Journal of Analog Innovation:http://www.linear.com/designtools/lt_journal.php

author: Zero999
author_rank: Super Contributor
timestamp: June 30, 2011, 04:13:13 pm
content: You could water cool the other side but I doubt you'd get enough power to do more than run a pump for the water.A Peltier heat engine is very inefficient, you're better off running a small steam turbine, the only advantages of Peltier are cost, weight noise and that there are no moving parts.

author: saturation
author_rank: Super Contributor
timestamp: June 30, 2011, 05:49:34 pm
content: This was recently in the news:http://www.tuaw.com/2011/06/14/hatsuden-nabe-thermoelectric-cookpot-keeps-your-iphone-battery-c/

author: Zero999
author_rank: Super Contributor
timestamp: June 30, 2011, 06:02:20 pm
content: A novel idea but look at the price!I suppose there are other applications. You could use a Pelter to power a pump for a power shower for use on a camp site where there's no access to mains water pressure, just a tank or a portable dishwasher.

author: Time
author_rank: Frequent Contributor
timestamp: June 30, 2011, 06:19:30 pm
content: You could harvest power from a car engine if you directed air flow over one side of the plate.

author: saturation
author_rank: Super Contributor
timestamp: June 30, 2011, 10:45:37 pm
content: Here's more, going back > 100 years:http://www.neazoi.com/technology/thermocouple.htm

author: johnwa
author_rank: Frequent Contributor
timestamp: July 04, 2011, 08:15:01 am
content: Quote from: saturation on June 30, 2011, 10:45:37 pmI think the original source of that article may be over here:http://www.douglas-self.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm. The rest of Doug's site is worth checking out too if you haven't seen it.It probably wouldn't be too difficult to build something along these designs with access to suitable metalworking facilities. Of course, there are a few constraints to the design: you would need readily available, cheap metals with high thermoelectric coefficients, and a construction with minimum electrical resistance between ends of the elements, but high thermal resistance. Given the quantities involved to generate a reasonable voltage, construction might be a bit tedious, but it would be an interesting project. I might have to put it on the end of the list of things to do...