Thermocouples, and Power Generation

[joe4324]

Ok, I'm always on a mission to figure out how to get power, and my latest scheme is extremely low tech, but before I build a prototype I need to do some more research. I need to find the most effecient power producing thermocouple (peltier) . But I dont know if there is a specific type or style of pelt that is better at producing energy.

I'd like something that is at least capable of dishing out a few watts, without a huge temp differential. At one point I had a 80watt TEC, and I had one side in ice water, and the other side on a hotplate, A spread of over 80C! and it only produced a fraction of a watt, and virtually NO amps. This leads me to believe that the type of TEC i had, was not suitable for generation power.

what criteria do I need to look for?

If anyone is really interested I can fill you in on my plan, its really simplistic. but I figured I'd prefer not bore you yet.

Thanks!

 

[PottedMeat]

hmm maybe see how efficient the ones on the voyager/cassini radioisotope TEGs are?

http://en.wikipedia.org/wiki/R...ermoelectric_generator

 

[joe4324]

that is very cool!!! I've never seen a radioisotope TEG before!

My design is actually VERY similar in principal, instead of using plutonium-238, I'm going to use decaying plant matter (grass clippings!) inside of a sealed and insulated unit. as the material decays, it will produce heat, the insulation will retain much of it, the TEC module will have a heatsink on Both sides, one inside the box, to gather the heat, the other on the outside to disapate the heat.

Ever seen a pile of grass steaming when its cold out? it can get so hot it can burst into flames!!! this is how many barn fires start!

I'm not sure how much energy could be produced here, but there is alot of energy embodied in that decay matter. if I could get even 2-3% effeciency, I might be on to something!

 

[joe4324]

but basically, I need to know what type of TEC's t hey used on that power module, and I need to get my hands on a few of somthing similar, I dont know if its as simple as going and order some TEC's the overclockers use or not, I dont believe it is.

 

[dkozloski]

35 years ago the University of Alaska placed remote seismographs all over the state that were powered with thermocouples heated by a kerosene lamp. Maybe you're reinventing the wheel. Check the green hippy alternate power web sites.

 

[Gibsons]

you can buy one ready-made from here maybe just stuffing some compost in something like this would be enough for a pilot experiment.

 

[joe4324]

hehe I come from the green hippy websites This concept has been applied for alot of things, infact the earthship people (www.earthship.org) have even made couches and love seats, that have a big removable chamber inside that can be filled with compost, producing a trace amount of heat in the winter, then you use it for starter soil in your potted plants in the early spring (I love this idea!) I'm sure this has been tried somewere along the lines, but I'm just curious to see how well it works, and what the limits of various designs are.

I've found sites with TEC's that already have bonded heatsinks and what not, but I'm curious if theres anyone here that knows of a specific kind/type/brand that is specifically geared towards power generation, and if so were I can get them.

 

[DrPizza]

Thoughts:
trap the methane... use methane as fuel
stirling heat engine

I just did a quick search for the heck of it...
http://www.lanl.gov/mst/engine/
looks interesting
Hmm... wow, quite interesting in fact... maybe not quite what you're looking for (other sterling engines might be better)

 

[joe4324]

Fantastic Idea. harvesting the methane could be as simple as a tiny valve, that dumps into a ballon! There would be plenty of excess methane left over during decomposition.

I could not only harvest the 'heat' of decay for my TEC's to produce power, but I could have excess methane to do 'whatever'

 

[joe4324]

So does anyone have any ideas? or anything to add? there is an awful lot of IQ here, surely some can peer my way!

 

[cirthix]

I have a design for a peltier power generation device that requires no maintenence, but no materials to make it. one of these days i'll get around to it

 

[joe4324]

Do Tell!

 

[cirthix]

fishtank with aluminum black anodized plate on top, peltier mounted on top of that, insulation covering the bare metal, and a large heatsink above that, with a duct for wind to cool it off. flip the whole contraption up-side-down and aim at sun. i dont know if it would work, but it woudl be pretty cool if it did.

 

[joe4324]

I'm sure it would work to a degree, obviously moderately -low- power, but thats ok for trickle charging or ultra low power consumption devices, yet again in that device also, you need the highest effeciency Pelt you can get your hands on, it needs to make the maxium power it can with the lowest temp differential, so the question is how do we find out, How to find out what pelt that is! arg.