Researchers at The Korea Advanced Institute of Science and Technology have developed a thermo-electric generator which resides in a light, flexible glass-fabric, and which can be powered by body heat.
When using KAIST's TE generator (with a size of 10 cm x 10 cm) for a wearable wristband device, it will produce around 40 mW electric power based on the temperature difference of 31 degrees F between human skin and the surrounding air.
To put this in context: Based on Table 9 ("Average System Power (mW)") of this research paper into smart-phone power consumption (based on the Openmoko Neo Freerunner) we'd need at least 10 times that (400 to 1100 mW) to power our phones.
(Score: 4, Interesting) by tftp on Sunday April 13 2014, @11:57PM
To put this in context: Based on Table 9 ("Average System Power (mW)") of this research paper into smart-phone power consumption (based on the Openmoko Neo Freerunner) we'd need at least 10 times that (400 to 1100 mW) to power our phones.
The phone needs 1W to operate. The paper says that the phone, in suspended mode, needs 60 mW. This means that you can keep the phone off, and 10 minutes of wearing the generator will give you one minute of talk time. This is not that bad if you are lost and need the phone for a 911 call.
(Score: 2) by prospectacle on Monday April 14 2014, @12:49AM
You're right. You could attach an emergency-recharge pack in a watch-like casing. Meanwhile you use and charge your phone as normal, but if you ever get caught out, you've got a few minutes worth of power stored in your wrist-band.
For more surface area they could make power pants.
I concede that the last sentence in the TFS may have looked dismissive, but it supposed to be; it was simply meant to address the question "So how much is 40mW in practice?". I figured a smart-phone is an example use-case that most people would be familiar with.
If a plan isn't flexible it isn't realistic
(Score: 2) by prospectacle on Monday April 14 2014, @12:52AM
"... last sentence in the TFS may have looked dismissive, but it wasn't supposed to be.."
If a plan isn't flexible it isn't realistic
(Score: 2) by tynin on Monday April 14 2014, @02:37AM
Thanks for the correction. In my tired stupor, it did appear dismissive.
(Score: 2) by wonkey_monkey on Monday April 14 2014, @09:39AM
I don't think that's a very practical usage case, in that I don't think anyone's going to slap on their thermo-electric charger strip in case they get lost, when they could just take a spare battery or any of the many more useful (for this case) charging solutions that already exist.
systemd is Roko's Basilisk
(Score: 1) by tftp on Monday April 14 2014, @10:08AM
Well, the problem is that if people expect to get lost then they not only take the spare battery - they also do not get lost. Accidents happen primarily by accident, totally unexpectedly. The best use case for such a thing is to be built into clothing or some very common piece of equipment, like a backpack, so that it is always available, even if you do not take it with you intentionally.
I cannot say how efficient it would be, but one would think that even an hour of solar (or thermal) charging to call 911 is not too much if the alternative is to not survive. One can be in trouble only half a mile from the civilization, in an area of excellent cellular coverage. It's only a simple matter of parking at the shoulder of the road, walking for a minute into the forest, and then falling into a creek and breaking a leg, or having a heart attack...
But generally only the market can tell how much this device is wanted.