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Body Heat Could Charge Your Cellphone
An anonymous reader writes to mention Nature is reporting that scientists have discovered a much more efficient way to use silicon to convert heat into electricity. This offers the possibility of many different applications including possibly charging your portable electronics just by wearing them close to your skin. "The concept of converting waste heat into electricity isn't exactly new, but it never really materialized due to efficiency hurdles. Now, scientists from the U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley think they may have found a key [to] increase the conversion efficiency by a factor of 100."
...welcome the icy grip of our soul..err..HEAT-sucking robotic overlords.
Now I have the ideal excuse to have Kathleen Turner's number on speed dial!
Between the cell phones being charged by shaking them, by solar power, and by body heat - at what point will they be blowing up in our pockets?
Slap Slap Slap - But m'aam, I just wanted to charge my cellphone and your breasts were handy.
Table-ized A.I.
Between the cell phones being charged by shaking them, by solar power, and by body heat - at what point will they be blowing up in our pockets?
I claim dibs on Rice Crispies-powered phones
Table-ized A.I.
Think bigger. Put these and some batteries near your brakes or under the hood of your car. Line the Shuttle with them, attach them to the boosters that get jettisoned. Tape them to politicians so all the hot air charges them.
I was thinking of converting to paganism, but where the hell can you find sacrificial virgins these days?
I just hope the word "insert" doesn't appear in the instructions.
Brett
Note that this of course does also need a temperature gradient to work. This is no magic electricity creating cooling device.
...huddling before a fire, desperately trying to stay warm as their PDAs, cell phones, wireless earphones, etc. suck the little remaining heat from their bodies. wait a minute, by the time this tech becomes widespread that might be me.
I thought it was measured in percentages, but I'm obviously misunderstanding something, because I'm sure it isn't becoming 100% efficient. And if it did mean percent, that would put current efficiency below 1% efficient.
So was it worded badly, or am I just a moron?
Thanks,
Anonymous Coward (666)
they talk about waste heat from steam turbines and car exhaust... and human bodies
is the sun's heat not enough to generate a substantial amount of energy? what would encasing one of these in a sealed dark glass box at lower latitudes do... or even inside of a hot car for that matter
Paging Dr. Carnot, Dr. Nicolas Carnot, call for you on line 2...
Human body thermal output is about 120 watts on average, skin surface area is 2 m^2, so a 50-cm^2 cell phone body can intercept 0.6 watts of body heat. BUT, the laws of thermodynamics place a limit on how much of that heat can be converted into useful work to charge the batteries in the phone. That limit depends on the temperature of the heat source and sink.
Suppose one side of the phone is in contact with your skin at 32 C (305 Kelvin), and the other side is in contact with room-temperature air at 27 C (300 K). (In practice, the temperature difference will be smaller, because the air near your body will be warmed above room temp.) The maximum efficiency one could get from these thermodynamic efficiency is (305-300)/300 = 1.7%.
And that's the theoretical maximum possible conversion efficiency. Real systems rarely come close to that.
SO, the most energy we could possibly get out of this generation system is 0.6 * 1.7% = 10 milliwatts. My iPhone's battery holds about 2400 mW-hours of juice, so if I installed this charging system and held it against my skin 24/7, it would take about 10 days to charge in the theoretical best case... and in practice, much longer than that.
This idea's dead in the water at the basic physics stage, before we even get to the engineering considerations.
What would encasing one of these in a sealed dark glass box at lower latitudes do... or even inside of a hot car for that matter
Nothing. It needs a thermal flow to work, i.e. a hot end and a cold end. Just putting it in a uniformly hot environment is useless.
Hope that wasn't classified or anything - but then Dad passed away a while back.
Request your free CD of my piano music.
Is this effect reversible? Could it be turned into a super-efficient Peltier module?
You are always moving. Most likely the phone is in your pocket moving with you.
Have you seen those ever lasting flashlights. Which use a magnet, a coil and a capacitor. The same concept could be used here. It might not keep the phone charged for heavy users but it could be a nice supplement to the charger.
Maybe if they really got creative they could reuse the coil and magnet as the vibrator.
OH and I didn't read the article. These are both interesting idea's but how much power can we really extract.
I've recently seen an upswing in the abuse of the inthishouseweobeythelawsofthermodynamics tag.
There's nothing about changing heat into electricity that violates the laws of thermodynamics.
It may not be super-efficient, but it's "free" energy in the sense that it body heat will be created anyway, you may as well try to redirect a portion of that energy into something useful.
I wonder whether RTGs will see a benefit from this? That would give many possibilities for cool deep-space missions.
How about using these in a water-heater sized device in your home. With a isotope heat source at the bottom, a coil lined with these strings, filled with some kind of heat transferring liquid (say, water). You could put one of these in every home and without any moving parts (as in a traditional thermonuclear generator with giant turbines) it would be very reliable.
Wasted power from Human exhaust... beens anyone
"For longest time, I wouldn't belive it...and then I saw the fields with my own eyes. Watch them liquefy the dead, so they could be fed intravenously to the living. And standing there, facing the pure horrifying precision, I came to realize the obviousness of the truth. What is The Matrix? Control. "The Matrix is a computer generated dream world, built to keep us under control in order to change a human being into this." Morpheus holds up a battery to Neo Neo begins to panic.
"at what point will they be blowing up in our pockets?"
I believe Bill Clinton has one of those.
We have guests over, and their 20-something daughter seems to have a mobile glued to her ear. I was wondering if it had a nuclear powerplant or something keeping it going. Immediately struck me that it would great if the phone could somehow be powered by body heat.
Could give them all the power they will ever need!
So, is this a way to finally find a use for all those excess fast food calories?
(fun intended)
but what do I do with this methane gas I'm collecting?
I'm always up for a heated discussion.
Wanna fight ? Bend over, stick your head up your ass, and fight for air.
So how soon until I can recharge my MacBook Pro with crotch heat? I'm thinking, maybe, perpetual porn machine.
I thought the Seebeck effect already had a conversion efficiency of 2-3%. How can you possibly increase that a hundredfold without breaking the laws of thermodynamics?
/ Per
"[Scientists] may have found a key increase the conversion efficiency by a factor of 100." Let me guess, this is involves some form of fusion.. and the machines have found all the energy they will ever need. This happened in a dream once, that I was so sure was real..
Request your free CD of my piano music.
Can I get this sucker to cool my CPU? Hotter, more power, faster the fan spins. I bet it draws down the heat when it extracts energy (required by laws of thermodynamics) and equalizing the heat between the CPU and surrounding air should provide power rather than take it. Really hot here, not hot here... that screams power.
It is no longer uncommon to be uncommon.
Does the technology work on stone-cold b*tches that dump you?
Take Nobody's Word For It.
I don't think you have to worry. According to the RSA website (http://www.rsa.com/rsalabs/node.asp?id=2327) you ought to be able to wear that shirt in any country, except "Cuba, Iran, Iraq, Libya, North Korea, Serbia, Sudan, Syria, and Taleban-controlled areas of Afghanistan as of January 2000". Also, it appears RSA can be implemented in only 2 lines of Perl now! (http://www.cypherspace.org/adam/rsa/)
Also, it appears RSA can be implemented in only 2 lines of Perl now!
Well, that's technical advance for you! I'll have to find that code. I expect it'll look like pure line noise. Also, I was being a bit generous with my original "4-line" description, since I counted the first #!/usr/bin/perl line, and that's not really what you could call perl code. Others only count it as three lines.
I did like the "-export-a-crypto-system-sig" comment in the original. Like many perl geeks, I have used it as a sig off and on over the years.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
I can't even count the number of times I've wanted to take a cellphone from someone who was talking while driving and shove it up their ass. Now, I have an excuse.
Have gnu, will travel.
Well if body heat can charge a cell phone battery, surely the ball-burning heat the bottom of my laptop kicks out can charge it's own batteries and double my unplugged time??? ~m
"Yes, I have a Disaster Recovery Plan. It's called my Resume"
Is this effect reversible? Could it be turned into a super-efficient Peltier module?
It ought to be.
The problem with Peltier cells is the conduction of heat across the cell by means other than the charge carriers that perform the heat pumping/thermoelectric generation. This breakthrough is a drastic reduction in heat conduction. So it ought to be applicable to both heat pumping and generation. In fact the efficient thermogenerator ought to be an efficient heat pump as well.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
I dunno where the heck you live but 27C is NOT room temp. "Room temp" is 20-22C. If my house was 27C year round I would not be able to wear pants!
Assuming a more *NORMAL* room temp of 21C, the updated calculation is (305-294)/294 = 3.7%, or 21.76 milliwatts.
That is 4.5 days to charge fully from 0.
And you're also forgetting the point of this is not to take a dead battery from 0% to 100%, it is to MAINTAIN your current battery. As such I think this system could theoretically easily make it so you would rarely have to charge your battery.
There are various research organizations (IMEC Belgium) looking into how to use the body's energy to power implantable devices (defib's, pacemakers, etc.) rather than batteries. They are looking at thermal, chemical, kinetic methods. The concept is birth to grave implantables that can also flex as the body grows and ages. They will be successful at some point. So it's a matter of developing these scavenging techniques, along with ultra low power semiconductors that will provide a foothold into the market. Once that happens, we all know the story. Incremental improvement, lower costs, larger markets, greater success. Whether you can do this with a power hungry cell phone remains to be seen. For cell phones, the big energy draw are the RF power amps behind the antenna. The distance to the cell towers will determine the minimum energy needed. Maybe pico cells at shorter distances are the key. On a lighter note. If they can develop internal energy scavenging, then I say they put a few USB ports on the outside of the skin. You've got the external supply and a friggin GREAT DIET PLAN!. Hey, you want to lose a few extra pounds, go to the airport and let travelers plug into you. Lose weight AND makes extra bucks! I'm writing a book called LOSE POUNDS WHILE YOU PLAY WOW! There's the answer to childhood obesity, and mobile energy.