Wake Forest "Power Felt" - thermoelectric fabric

[I4AT]

I caught a brief segment maybe halfway through about this stuff on the Science TV network. For anyone not familiar you can probably do a search to get the gist of it, but it's basically a "thermoelectric fabric" that uses a layer of carbon nanotubes to transfer body heat into small amounts of power.

Their supposed scenarios include things like t-shirts that can power your MP3 player as you jog, or lining car/airline seats with it to generate power for various devices, or putting a patch on your phone to pick up heat from your hand, etc.

Not gonna pretend to know the science behind how it works, but what I'm wondering is, is there a technical reason why all their theoretical applications are related only to body heat, and not other sources of heat?

For example, rather than lining your car seat with it, why not put it directly against the radiator/manifold where the heat generated by the engine is several fold over what your body would generate?

Or rather than applying it to the back of your phone to pick up heat from your hand, why not directly against the battery/CPU which is bound to be much warmer?

Could a sizable patch of this stuff not be lined against a large passive heatsink in a desktop/laptop to generate power from the CPU/GPU itself which could easily be at least twice as warm as your hand or chest as you jog?

I doubt anyone smart enough to come up with this stuff would simply overlook this, so I'm guessing there must be some reason their ideas are all related to heat generated by the body rather than heat in general. Maybe anything warmer would cause the plastic that holds the nanotubes together to melt? But if so, couldn't they just come up with some other type of binding agent that has a higher temperature tolerance?

Just from my Everyday Joe understanding, could this stuff one day be used to double battery life in our laptops and other devices simply from the heat already being generated by the various processors? Or greatly increase the power efficiency of desktops by recycling the heat produced into power?

 

[PottedMeat]

http://phys.org/news/2012-02-power-felt-body-electricity.html

<quick googling>

it would be nice if they just flat out said what they could get like "1uW/layer/mm^2/deltaC"

As the researchers explain, the amount of generated voltage (and total power output) is equal to the sum of contributions from each layer. So adding layers to the fabric is equivalent to adding voltage sources in series, and the number of layers is limited only by the heat source&#8217;s ability to produce a sufficient change in temperature throughout all the layers. Here, the heat source&#8217;s temperature is limited to 390 K (117 °C, 242 °F), the point at which the polymer begins deforming.

seems like they got it working with a body heat differential and are trying to see how far that can go for now. improving durability would be later.

 

[I4AT]

Interesting, so already that's within the range of most consumer grade processors like i7's, although definitely not there yet to be applied to a running engine.

I'm completely ignorant to the Kelvin scale, so what exactly is a temperature difference of 100K in terms of C/F? I guess taking rough estimates just from what I'm used to with onboard sensor readings in most desktop/laptops the temperature difference can be as high as 50-60 degrees C with a fully loaded i7 in the mid 80-90C range vs ambient air temperatures of around 30C or so.

How much is 5 µW power (supposedly reachable with a 100K temp difference) in terms of your average electronic device?
(Edit: After a little searching, it seems this is 5 "microwatts" which is even less than a "milliwatt"? Doesn't your typical USB 2.0 port supply up to 500 milliwatts of power? Something seems off about that, cause I remember the guy saying lining all the seats of an airplane could power all the onboard electronics with passenger bodyheat alone... but 5 microwatts is almost nothing?)

So I guess it's not that they can't use this stuff in better applications than a sweatshirt, they're just listing possible real-world applications due to the current cost per watt generated by an actually affordable patch?

I wonder what this stuff could do in a football stadium lining the seats of 70-100 thousand fans?

 

[sm625]

Thermoelectric power generation is just a gimmick. You generate so little power that it can never be practical. The tiny little windup generator inside a typical watch will generate an order of magnitude more power than any thermoelectric power generator of similar size. It would be far more practical to use a little windup knob, or just use a battery, and recharge that battery using standard methods.

 

[inachu]

ESD jackets also contain carbon to reduce ESD on SMT production lines or other places that are sensitive to electrostatic discharge.

https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1280&bih=598&q=esd+jackets&oq=esd+jackets&gs_l=img.3..0.1799.4608.0.4725.11.11.0.0.0.0.97.531.11.11.0.ehm_qwpr...0...1.1.61.img..0.11.531.FlI1UbNagSM