Using a peltier in reverse on a CPU

[Thunderchild]

I was thinking ! a peltier cell can be used in reverse to make electricity from heat. what if one was put between a CPU/GPU and the heatsink+fan ? surely some power could be recovered ? considering in my case i run the cpu at 100% all the time as its running boinc (distributed computing software helping various projects such as fighting aids) I know I wouldn't be running my cpu free but well even a few percent of return would help.

 

[blueroomelectronics]

Teeny weeny amounts of power, plus your CPU will overhead. No free lunch you'll be spending more power than you recover.

 

[Thunderchild]

well how efficient are peltiers ? if they will pass through them any excess heat then it will be eliminated by the heatsink and fan

 

[blueroomelectronics]

How much energy are you hoping to get? 0.5V at a few ma? Where do you think the thermal energy is coming from? Your fan will have to work harder to keep the CPU cool and the thermal difference between the fan and CPU will be only a couple degrees so you won't get much out of it and your CPU will simply run hotter as the thermal bond isn't there with the heatsink & fan.

 

[Hero999]

Sounds like a silly idea.

Blueroom is right, it will increase the amount of power required to cool it.

It takes 'work' to move heat and 'work' can be done from a temperature differential. The second law of thermodynamics explains why this idea won't work.

Second law of thermodynamics - Wikipedia, the free encyclopedia

 

[duffy]

It is a silly and Bad Idea.

Peltier cells are more efficient than termocouples at recovering heat energy. The Russians built a radio that was powered from a kerosene lantern with a bunch of thermocouples - perhaps a peltier cell version of THAT would make for a nifty project!

 

[kchriste]

Good idea for your wood stove:
wood stove fan
But a bad idea for your CPU as already mentioned.

 

[Thunderchild]

hm thats a good idea, make a wood burner coated in peltier cells

 

[Nigel Goodwin]

hm thats a good idea, make a wood burner coated in peltier cells

You might have noticed, that power stations heat water to create steam and spin turbines - they don't use big banks of Peltier elements - do you think there might be a good reason for that?.

 

[Thunderchild]

cost maybe ? not everyone can set up a steam turbine in their back garden, I'm talking main accademicly really I'd probably never put anything into practice

 

[duffy]

Size constraint, too - if he has a steam coils, a turbine, a generator, and a condenser in his living room, where is he going to sit?

 

[Nigel Goodwin]

cost maybe ? not everyone can set up a steam turbine in their back garden, I'm talking main accademicly really I'd probably never put anything into practice

More efficiency than cost - although the cost would rocket due to the MUCH lower efficiency.

Perhaps you ought to buy a peltier and experiment?.

 

[Thunderchild]

well I might tinker around, actually i recall as a child (not too long ago mind you) there were model steam engines around that ran miniature circular saws and the like they might be worth coupling to a generator (just for kicks of course)

 

[Nigel Goodwin]

well I might tinker around, actually i recall as a child (not too long ago mind you) there were model steam engines around that ran miniature circular saws and the like they might be worth coupling to a generator (just for kicks of course)

Check out 'Mamod' who have been making model steam engines for decades.

Mamod Online Shop

 

[Thunderchild]

hm interesting but not quite what I'm talking about. these were on a base and were basically a (miniature) steam motor that ran a miniature "tool" I suppose they were more for demonstrative purposes and a bit of fun, and I'm sure that "health and flipping safety" had something to say about them: What !? fire, matches, pressure, circular saws.... hm did these "fun" things survive the war on how to stop supid people harming themselves by taking fun things away from ALL people. I've been out of the picture for 15 years so don't know.

 

[Thunderchild]

ah found them - of course "stationeries" mind you a bit of a prohibitive price for me I'd want to know more of their carachteristics too

 

[blueroomelectronics]

How much energy are you hoping to extract? What do you want to power?

 

[Nigel Goodwin]

ah found them - of course "stationeries" mind you a bit of a prohibitive price for me I'd want to know more of their carachteristics too

They are more an educational toy than anything else, but steam engines aren't efficient, and small ones certainly not

Back when I was a kid, a lad up the road (called David Evans) used to have a Mamod stationary engine, along with a complete fairground that it powered.

Pretty cool thing.

 

[Thunderchild]

How much energy are you hoping to extract? What do you want to power?

it would be a bit of educational fun more than anything else

 

[duffy]

Have you seen this guy's site?
Crabfu SteamWorks