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Body Powered Batteries -- Thermoelectrics
An Anonymous Coward writes: "According to this story on Yahoo, the folks at Applied Digital Solutions have "developed a miniaturized thermoelectric generator -- a half-inch diameter ceramic-based `battery' that converts low gradient body heat flow into electrical power." Right now they can power watches or small medical devices. How long before these things can power my handheld?"
I assumed the release was just written by a clueless person when I saw "10 micron amps". Poor fool just meant "10 microamps".
Then later down I see a quote by the *chief scientist* saying that they plan to develop a battery "capable of generating 3 volts of electricity with 10 microns".
Maybe I'm just an idiot, but the only definition I know of "micron" is a unit of linear measure. I have no idea how this would relate to anything electrical. I'm still cautiously assuming they meant "microamps", but does anyone have any other ideas?
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seiko has a bunch of kinetic watches that go into a low power mode when they stop moving. The hands freeze, but time is still kept. when it realizes that it is being moved again, it puts the hands in the correct place and continues on it's way. I believe the latest ones will keep time for up to a year without movement.
This article at NY Times has an interesting article on other methods of using body energy to power things.
It mentions methods such as cranking and pumping, and of course, stride (i.e. stride-powered watches). One company created a human-powered electricity generator which creates electricity by hand pumping. If you pump one of these for a few minutes, it can power a cell phone for around 20 minutes.
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The problem is that you need a temperature gradient. Inside the human body there is hardly any gradient, so this wouldn't work without part of the device being outside the body. Even then, I am sure there's no way this method comes close to generating the power needed for an artificial heart.
Admittedly this post is about passively generated electricity, but there's also been some work on electricity generated by harnessing activity such as walking. This company for example, has been using peizoelectric devices to generate a few milliwatts of power from walking/running activities. For the most part the energy produced is insufficient for anything other than trickle-charging batteries.
/. putting little piezoelectric generators under each key of the keyboard, and under those mouse buttons would beat those peizoelectric shoes anytime!
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>How long before these things can power my handheld?
Yes! They can provide 100's of watts!
These have been used for years to power deep-space satellites such as Pioneer 10 (solar power tends to not work too well when you get away from the sun). Plus, no moving parts to fail. They use radioactive decay as their heat source.
They use plutonium-238. It half-life is 87.8 years and emits primarily alpha particles, a non-penetrating type of radiation which requires little shielding.
Here's a good page from nasa and another from the doe
Power ranges from milliwatts in 1964, to "multi-hundred-watt" in 1977 (the sole power source for voyager), to 208 Watts electrical (+4500W thermal!) in 1990, to 507 Watts (electical) in 1997.
Practically, there's that whole radiation thing, plus some costs to enrich the material, and then also disappating the thermal energy released (it operates on a gradient, so you've got to have a cold end to counter the hot end)
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It's always bothered me, in "The Matrix," the way that they harvest humans as batteries. If the AI was all that intelligent, they would have known that the energy investment in farming humans would be greater than the output. YES, the human body does output X joules of energy, but in order to output that energy in a harvestable form an even greater amount of energy has to be invested. Without the sun's energy all of life on earth would die, farming like that would not be practical.
thermoelectric batteries are totally new...
Link to the Citizen Eco-Drive Thermo watch...
"Eco-Drive Thermo converts the temperature difference between the user's body and the surrounding air into electrical energy to power the movement. [...] The original Eco-Drive Thermo was launched to great acclaim at the 1999 Basel Show."
Don't know if it's shipping to consumers yet, but the technology's been around for a while.
Thus, it would be meaningfull to talk about any of these or any products (e.g., area x thickness --> volume, voltage x amps --> watts, etc.) and micron amps would be some sort of effectiveness metric (backed, presumably, by some assumptions about body temp, room temp, etc). If this interpretation is correct, for device rated at x-and-so micron amps, total power would be proportional to total area.
On the other hand, it might just be a typo.
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Another post in this thread correctly states that the energy is stored electrically in a capacitor, not a spring.
I had a summary of the concept all set to submit, but like an idiot I tested my url with the same browser session I was submitting with, and lost it! No time to re-type it. The links tell all.
My kid in the Navy brought a fake one home last winter, and I'm going to take it apart to see how close the knock off is to the real one :)
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I have one of these; they're pretty neat. First of all, they can maintain time for about 2 weeks without being worn/moving. They store energy in a small capacitor, but when it gets low it only ticks every other second to conserve power. It's pretty sweet
The only things that I'd add into the whole mess:
1. Didn't Morpheus mention something about "a certain form of fusion"? I'm assuming something biological is required for that to work. (Hey, it's called science fiction for a reason.
2. Without sunlight, we can assume that most of the life on Earth got zapped (humans always watching out for themselves). From there it would have been pretty logical to go from "destroy humans" to "capture/harness for fusion system/keep trapped in system". (Maybe the Matrix requires some sort of neural net to run - aka, the machines *need human brains to keep their own programs running*, which makes them even more dependant on us as we are on machines (which lets Morpheus's comment on the irony of humans using tools make sense).
You'd have to assume that by the future, other sources of power (nuclear, oil, etc) are also depleted (which may have launched the whole humans vs AI war to begin with - maybe they didn't *want* to have the energy star label on their monitors...)
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This is one of those technologies that could have great potential both in the biomedical field and in the portable device field. Unfortunately, the article doesn't give much detail - and has a couple of strangely glaring errors (10 microns?)
From what I remember of RTGs (Radio Thermal Generators - like those used on Deep Space probes) rely on a temperature differential to generate power. With a body powered unit, you'd be looking at drawing power from the difference between human body temperatute and the ambient temperature outside.
If it's 98 degrees outside, hope you have -real- batteries around to provide power.
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Ceramics is likely just the closest familiar idea. The overwhelming majority of the good bulk thermoelectrics (and all of the nanostructured ones I'm aware of) are made of semiconductors. Not Si or GaAs, but more exotic ones like bismuth telluride (Bi2Te3), bismuth antimony (Bi-Sb, an alloy), &c. In general they come from the bottom right f the periodic table and are pretty toxic and expensive to make -- about equivalent to the CdTe in solar cells.
That said, there are already thermoelectric devices being used to reclaim waste heat in power plants. Also, the NASA Voyager space probes use thermoelectric devices coupled to a radioactive Pu source to generate their juice - mostly because thermoelectrics are pretty reliable devices.
More applications are in cooling -- using the opposite physical effect for localized cooling, especially for applications where vibration or noise are problematic. Laser diodes and some other IC devices use thermoelectrics for cooling (or at least temperature regulation). Larger applications, like household refrigeration, aren't practical (despite the environmental benefits) because the efficiency is ~10%, compared to 30% or so for your fridge and ~90% for the enormous air conditioners in office buildings.
Current research is largely driven by electronics folks -- wouldn't it be nice to get rid of those noisy, bulky fans in your computer?- and is focusing on, of course, nanotechnology as the answer for improving the thermoelectric figure of merit.
--Janell
Is it really obvious this is the subject of my (ongoing) chemistry PhD work?