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Duke Univ. Device Converts Stray Wireless Energy Into Electricity For Charging

Soulskill posted about 8 months ago | from the harvesting-the-ether dept.

Power 216

Lucas123 writes "Engineers at Duke University say they've constructed a device that can collect stray wireless signals and convert them into energy to charge batteries in devices such as cell phones and tablets. The WiFi collection device, made of cheap copper coils and fiberglass, can even aggregate energy from satellite signals and sound waves (abstract). The researchers created a series of five fiberglass and copper energy conductors on a circuit board, which was able to convert microwaves into 7.3V of electrical energy. By comparison, Universal Serial Bus (USB) chargers for small electronic devices provide about 5V of power. The device, the researchers say, is as efficient as solar cells with an energy conversion rate of 37%."

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216 comments

Units! (5, Funny)

olsmeister (1488789) | about 8 months ago | (#45372191)

7.3V of energy? USB provides 5V of power? Arggh. I think my head just asploded.

Too bad (4, Funny)

XanC (644172) | about 8 months ago | (#45372219)

This summary had such potential, too.

Re:Too bad (1)

gigne (990887) | about 8 months ago | (#45372229)

Having just read the "article", the units in the summary are a copy-pasta from the article.

Re:Too bad (1)

gigne (990887) | about 8 months ago | (#45372293)

ooohhh... I was way too slow on this. I just chraged in with a sensible reply. /self-whoosh

Re:Too bad (1)

Optimal Cynic (2886377) | about 8 months ago | (#45372437)

I wonder what a chrage jail looks like.

Re:Too bad (4, Informative)

TooTechy (191509) | about 8 months ago | (#45372239)

Ugh. And the unit we want is missing...

Look at Watt they make you give... (Clive Owen)

Re:Too bad (4, Funny)

Mr D from 63 (3395377) | about 8 months ago | (#45372241)

I am resisting the urge to laugh.

Re:Too bad (4, Funny)

Billy the Mountain (225541) | about 8 months ago | (#45372385)

Ohm my god!

Re:Too bad (1, Funny)

Rich0 (548339) | about 8 months ago | (#45372811)

Seriously, I'm dyne-ing here. Joule have to come up with a better joke next time.

Re:Too bad (1)

Anonymous Coward | about 8 months ago | (#45372949)

Watt are you saying?

Re:Too bad (0)

Anonymous Coward | about 8 months ago | (#45372971)

I'm also resisting the surge to laugh.

Yeah, I know (2)

roman_mir (125474) | about 8 months ago | (#45372315)

It sounds very positive.

Re:Too bad (3, Funny)

Arancaytar (966377) | about 8 months ago | (#45372407)

At least this headline is current.

Re:Too bad (0)

Anonymous Coward | about 8 months ago | (#45372509)

Thumbs up for the pun! :-D

Re:Units! (4, Funny)

GenieGenieGenie (942725) | about 8 months ago | (#45372271)

If you smoke enough pot, as the authors of this cheap attempt at attention-grabbing surely must have, you start seeing double and 5V turns to 55W...

Re:Units! (0)

Anonymous Coward | about 8 months ago | (#45372689)

You sure it didn't double from 5V to 8V?

Re:Units! (1)

Anonymous Coward | about 8 months ago | (#45373085)

That's almost triple with 3V more of power!

Re:Units! (1)

moteyalpha (1228680) | about 8 months ago | (#45372279)

7.3V of energy? USB provides 5V of power? Arggh. I think my head just asploded.

It's a chain reaction! Now my head asploded with 7.32 Volts of energy and 10 coulombs of mass.
They could be dealing in metric electrons.

Re:Units! (0)

Anonymous Coward | about 8 months ago | (#45373031)

7.3V of energy? USB provides 5V of power? Arggh. I think my head just asploded.

It's a chain reaction! Now my head asploded with 7.32 Volts of energy and 10 coulombs of mass.

They could be dealing in metric electrons.

Oh yes... how many moles does it take to charge a lightbulb?

Re:Units! (1)

cephus440 (828210) | about 8 months ago | (#45372287)

Ah, I get it.. it's 7.3V of electrical energy but USB has 5V of ENERGY!

Re:Units! (1)

sumdumass (711423) | about 8 months ago | (#45372897)

Power is the total amount of energy available commonly expressed in watts or joules, sometimes horsepower when not specific to electrical current where as volts is part of the measurement used to calculate power when dealing with electrical currents. Amps is the second component of power in which you multiple the amps by the voltage to get the power in watts.

I don't know if you were playing on the mistakes and I ruined it for you or if you didn't catch the issue (it took me a minute to see it). I hope I didn't stop you from doing the Kessel Run in less than twelve parsecs.

Re:Units! (2)

WillKemp (1338605) | about 8 months ago | (#45372909)

The article says 7.3v into 70-80 ohms, which means about 0.7 watts. Or, if you prefer energy, that's 0.7 joules per second.

Re:Units! (3, Funny)

istartedi (132515) | about 8 months ago | (#45372299)

Just relax and drink a few amperes of beer. That'll help.

Re:Units! (1)

Anonymous Coward | about 8 months ago | (#45372409)

You can actually generate electrical current from beer, or at least from the brewing process [dailymail.co.uk] , so you could actually work out an ampere-equivalent rating per volumetric unit of beer (at a given voltage, of course). Okay, I sound waaay too nerdy.

Re:Units! (1)

Anonymous Coward | about 8 months ago | (#45372549)

....and a racist.....you read the daily mail!!!

Re:Units! (0)

Anonymous Coward | about 8 months ago | (#45372579)

Google must be racist, it returned that page as the top search result. The Daily Mail is too classy for me, I read the Sun.

Re:Units! (4, Funny)

wjr (157747) | about 8 months ago | (#45372323)

And if I scuff my feet while walking across the room, I can generate TWENTY! THOUSAND! VOLTS! OF! ENERGY! Someone hook me up to the power grid!

Re:Units! (2)

NatasRevol (731260) | about 8 months ago | (#45372777)

If you say so.

ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ...............poof!

crackle crackle crackle

hisssssssssssssss.....

Re:Units! (1)

mattack2 (1165421) | about 8 months ago | (#45372935)

I can't find the exact comic, and googling shows that the joke is an old one.. but one of the major comic strips in the past few weeks talked about a "static electricity car" where you rub your feet on the carpet when the battery starts to wear down.

Re:Units! (0)

icebike (68054) | about 8 months ago | (#45372331)

7.3V of energy? USB provides 5V of power? Arggh. I think my head just asploded.

Watts that you say?

Static electricity from petting the cat can yield charge of many thousands of volts.
Maybe our gadgets need to come with cat cradles.

Still, with every airport radar, tv station, radio station, power cable, the wires in the walls, and every other stray radio source, it would seem there is a lot of energy that could be intercepted before it all gets absorbed by the hillsides. I suspect you would need a pretty large collector on the outside of your house to gather enough for any worthwhile use.

Re:Units! (4, Funny)

Arancaytar (966377) | about 8 months ago | (#45372421)

charge of many thousands of volts

You're not helping.

Re:Units! (1)

icebike (68054) | about 8 months ago | (#45372449)

You're not helping.

Whoosh.

Re:Units! (4, Interesting)

TooTechy (191509) | about 8 months ago | (#45372499)

Way back in the 70's (early 80s?) I recall a guy who wrapped his whole house in copper wire making large coils to tap the energy from the overhead power cables. He powered his whole house off this which was a mistake. The authorities charged him with theft.

Re:Units! (4, Funny)

K. S. Kyosuke (729550) | about 8 months ago | (#45372589)

So you're saying that his house coil didn't resonate well with the utility company?

Re:Units! (5, Interesting)

Penguinisto (415985) | about 8 months ago | (#45372767)

Nope, it didn't, since induction was the key, not resonance. ;)

IIRC, the rig involved the peculiar way the tension lines ran in parallel to his roof peak-line. This allowed him to wrap a shitload of long, large wooden dowels with copper wire, then hang them in his attic, orienting them all parallel to the overhead lines. The results would be captured, cleaned-up, and then presented to his home circuitry as household power (120VAC, 60Hz, etc).

Pretty simple, really - but yeah, I remember his being charged with theft as well (though technically, I think nowadays that wouldn't fly as easily, since there have since been plenty of legal precedents made that allow you to make free use of any and all magnetic and radio energy that falls on your property, even if you get it through induction.)

Re:Units! (2)

DarkOx (621550) | about 8 months ago | (#45372851)

The trouble with great schemes like that is people always get greedy. Had he not tried to power the entire house with it, but say maybe just moved the circuits for several rooms as load for the induction coil, so that he still used some power from the grid and paid his bill, i bet he could have got about half his power free and they'd have never caught on.

Re:Units! (3, Interesting)

Penguinisto (415985) | about 8 months ago | (#45373019)

Exactly. For the win? If he had a few solar panels parked on his roof (even if they were never hooked up), it would easily explain why his usage patterns were screwy at times, explain a battery bank, and even (in states with solar tariff credits) allow him to sell the power company their own juice back.

Re:Units! (2)

K. S. Kyosuke (729550) | about 8 months ago | (#45372989)

Pretty simple, really - but yeah, I remember his being charged with theft as well (though technically, I think nowadays that wouldn't fly as easily, since there have since been plenty of legal precedents made that allow you to make free use of any and all magnetic and radio energy that falls on your property, even if you get it through induction.)

He could have said that the intent in planting the coils in his attic was to filter out the harmful EM energy before it reaches his bedroom and endangers his health in sleep. (Frankly, I don't know what to make of a situation when a residential house can extract energy like this. There must be some hygienic limits, aren't they?)

Re:Units! (1)

adonoman (624929) | about 8 months ago | (#45372539)

Maybe our gadgets need to come with cat cradles.

Professor Norton Nimnul has already beaten you to it.

Re:Units! (0)

Anonymous Coward | about 8 months ago | (#45372507)

This is slashdot, so knowing that volt is somehow related to energy is more than enough knowledge to know that something is wrong and its the goverments fault.

Re:Units! (1)

K. S. Kyosuke (729550) | about 8 months ago | (#45372563)

Now if only we knew the conversion coefficient between volts of energy and volts of power, we'd be able to compare the two numbers! Alas, I don't know it. And I'm not going to look for it, that would probably take too many volts of time.

Re:Units! (1)

safetyinnumbers (1770570) | about 8 months ago | (#45372651)

that would probably take too many volts of time

Light-years of time.

Maybe even parsecs.

Re:Units! (-1)

Anonymous Coward | about 8 months ago | (#45372567)

Im making over $13k a month working part time. I kept hearing other people tell me how much money they can make online so I decided to look into it. Wel, it was all true and has totally changed my life. This is what I do,

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Re:Units! (0)

RabidReindeer (2625839) | about 8 months ago | (#45372575)

7.3V of energy? USB provides 5V of power? Arggh. I think my head just asploded.

7.3V isn't power. It's electromotive force. To be power, you have to back it up with some amperage.

The question then becomes, how many amps? Do you need appartus the size of a mobile home to get enough to charge your cellphone?

Re:Units! (1, Funny)

Nethemas the Great (909900) | about 8 months ago | (#45372805)

Thank you Captain Obvious. What dark alley will you illuminate next?

Re:Units! (1)

WillKemp (1338605) | about 8 months ago | (#45372787)

Well, the work was supported by a "Multidisciplinary University Research Initiative from the Army Research Office" and, as they say, military intelligence is a contradiction in terms.

Re:Units! (1)

Major Byte (669826) | about 8 months ago | (#45372823)

Watts the big deal?

Re:Units! (1)

Megane (129182) | about 8 months ago | (#45372963)

You know the old saying, it's not the volts, it's the amps. (I can make thousands of volts just by combing my hair!)

Re:Units! (1)

dfsmith (960400) | about 8 months ago | (#45373141)

My cat can easily produce 5000V of "energy", so this is only 0.14% of stroking a cat. Hmm.

big deal (1)

Anonymous Coward | about 8 months ago | (#45372257)

i could make one at 15kV if i want
it'd provide less then 1 pico-amp, but hey. apparently only voltage matters...

Free (2)

Princeofcups (150855) | about 8 months ago | (#45372261)

Free energy from the ether! Not.

OT sig reply (-1)

Anonymous Coward | about 8 months ago | (#45372305)

The only thing worse than a Democrat is a Republican.

The only thing worse than Democrats and Republicans, is the both of them together.

Re:Free (1)

timeOday (582209) | about 8 months ago | (#45372895)

Actually reducing waste is the closest you can get to getting something for nothing. When you turn on a lightbulb, what percent of the photons emitted happen to bounce around and eventually fall through the lens on somebody's eye? Hardly any - it's a minuscule percent. Thus "solar"-powered wallpaper to re-absorb energy from lightbulbs sounds stupid but makes perfect sense, if it could be produced cheaply enough. Broadcast RF signals are similar.

And by the way, if you want to make a display that uses hardly any power, make one that only emits energy into the eye (perhaps using eye tracking). It's like the difference between earbuds and loudspeakers, i.e. a factor of thousands. My mp3 player runs all day on a battery smaller than a AAA, whereas the 15" sub in my livingroom can make the lights dim.

Re:Free (1)

JesseMcDonald (536341) | about 8 months ago | (#45373127)

Thus "solar"-powered wallpaper to re-absorb energy from lightbulbs sounds stupid but makes perfect sense, if it could be produced cheaply enough.

Not everyone wants to wallpaper the interior of their house in black. All that "wasted" light reflecting off the wallpaper is what allows you to see the walls.

Re: Free (0)

Anonymous Coward | about 8 months ago | (#45373145)

Solar powered wall paper, I'm assuming you mean light conversion wall paper ... Just think with an efficiency of 25%, which is pretty efficient, the reflectance is now 75% .... and light available in the room is now also only 75%, and the illumination level is reduced by 25% (of the collected light).

I have an idea: if the illumination levels can be tolerably 25% less, why don't you just use a light globe with less lumens & corresponding power consumption in the first place?

Meaningless numbers (0)

Anonymous Coward | about 8 months ago | (#45372303)

Voltage is meaningless, and the efficiency number provided is completely beside the point of whether it's USEFUL. The incident radiant energy form the sun is many orders of magnitude more energetic than the output of a WiFi router. I'm glad it's relatively efficient, but efficiently capturing a trivial amount of energy isn't an achievement, it's a hobby.

I'm skeptical this can provide energy to a cell phone even fast enough to keep up with the rate at which standby mode consumes energy.

Re: Meaningless numbers (0)

Anonymous Coward | about 8 months ago | (#45372391)

This. The more amps you try to pull, the more the voltage will drop. The voltage of a power source doesn't tell you very much unless you know how many amps you can pull without drawing the voltage down to nothing and/or overheating it.

Re:Meaningless numbers (1)

Anonymous Coward | about 8 months ago | (#45373171)

Voltage is meaningless, and the efficiency number provided is completely beside the point of whether it's USEFUL. The incident radiant energy form the sun is many orders of magnitude more energetic than the output of a WiFi router. I'm glad it's relatively efficient, but efficiently capturing a trivial amount of energy isn't an achievement, it's a hobby.

I'm skeptical this can provide energy to a cell phone even fast enough to keep up with the rate at which standby mode consumes energy.

Er, voltage is not meaningless. It's the speed at which the electronic charge passes a given point. Which means that it can easily provide energy to a cell phone fast enough to keep up -- the problem it that what it doesn't lack in speed, it fails to make up for in volume.

To put it differently, most portable electronics have charging circuits that require 2 amperes of electricity (size of the hose) travelling at 5 volts (rate of travel) for a total of 10 watts (2x5 - amount of actual energy at a given place and point in time), per hour. You're looking at between 3 and 50 watt hours storage in a portable device, and a charging efficiency of around 38%.

From that, you can fill in the variables to see what sort of amperage you need -- for example, a device with a 3 watt-hour battery often uses an average of 1watt/hr; throw in the 38% efficiency rating, and you know how long (rough napkin style) you need to charge during use at an amperage to keep in the positive.

However, ANY amount of charge, as long as it overcomes the inefficiencies, cost of manufacture/parts, and can be stepped up/down as needed, is useful. I'd love to have a collector that could take take in microamp bursts of high voltage (static electricity) and apply those collectively to a charging circuit throughout the day. If it could also absorb radio waves, sound, lightning bolts, direct hits from a kinetic weapon, etc. that'd be great! That means it'd effectively become a radiation "black hole" that I could use to create "walls" and dead spots. Use this material around a room that you want to protect from eavesdropping, while using the directed or reflected energy it absorbs to power whatever's inside. :)

Resistor (5, Funny)

Anonymous Coward | about 8 months ago | (#45372311)

Hey, I can get -174 dBm/Hz from a 50 Ohm resistor too. Free energy!

Re:Resistor (4, Informative)

McGregorMortis (536146) | about 8 months ago | (#45372351)

Your joke is too subtle without a reference.

http://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise [wikipedia.org]

Re:Resistor (2, Insightful)

Anonymous Coward | about 8 months ago | (#45372545)

Jokes like that are intended for people who get the joke and shouldn't need explanation.
I can tell you got it though :)

Re:Resistor (2)

Moof123 (1292134) | about 8 months ago | (#45373027)

I got it just fine.

Re:Resistor (1)

Nethead (1563) | about 8 months ago | (#45372871)

Are you sure that wasn't just coax gain?

microwaves at what field strength? (3, Insightful)

swschrad (312009) | about 8 months ago | (#45372313)

news flash: any antenna provides voltage. usually in the microvolt range. to get enough voltage like they did, say, enough to blow a FET in the front end of a receiver at basically no current, you have to put the antenna in one hell of a strong RF field. a field strong enough to produce enough current to charge batteries or operate CMOS circuits is a field too strong to stay in, according to FCC emission guidelines. so I see this as a project for a grade, and not a "discovery."

Re:microwaves at what field strength? (0)

Anonymous Coward | about 8 months ago | (#45372375)

Shhh...they're never going to get funding with all of your logic and rational!

Re:microwaves at what field strength? (1)

sfm (195458) | about 8 months ago | (#45372843)

Forget Wireless or Satellite signals, they are orders of magnitude less power than you can realistically use. You would do be much better off pointing your antenna at that 100KW FM transmitter up on the hill.

Re:microwaves at what field strength? (1)

rubycodez (864176) | about 8 months ago | (#45372873)

People have grabbed enough power out of the air to power their house, living near power lines and using hidden inductor.

Electromagnetic waves induce current in conductors, and bear eat fish and shits fishy shit in the woods! Story at 10!

Re:microwaves at what field strength? (0)

Anonymous Coward | about 8 months ago | (#45373089)

Significant voltage can be obtained from the higher-frequency end of the RF spectrum obviously since there is more energy there available to harvest. Say, into the Tera-Hz band. Such energy-harvesting devices already exist, we call them 'solar cells'.

Hey coach! (-1)

Anonymous Coward | about 8 months ago | (#45372335)

Duke Univ. Device Converts Stray Children Into Entertainment For Pederasts

7.3V? Psh! (3, Insightful)

Schrockwell (867776) | about 8 months ago | (#45372361)

I can build up a couple kilovolts by scuffing my shoes on the carpet.

Also, sure it might be 37% efficient, but do you realize how SMALL the density of RF energy is? The Friis transmission equation [wikipedia.org] gives you some idea: it decreases by the square of the distance away from the source, due to that power spreading out in a sphere. When you start off with only a couple mW of power and an omnidirectional antenna, there isn't much power left to harvest when these tiny receiving "metamaterial" antennas are even just a few feet from an access point.

Re:7.3V? Psh! (1)

Megane (129182) | about 8 months ago | (#45372985)

Sure, but if you live next to a radio transmitter or under a power line (ever held a fluorescent tube lamp under a power line?) then you'll just be raking in free electricity!

For $4, you can read the paper (5, Informative)

Animats (122034) | about 8 months ago | (#45372363)

Here's the actual paper's paywall. [aip.org] All the paper claims is that "A maximum of 36.8% of the incident power from a 900âMHz signal is experimentally rectified by an array of metamaterial unit cells." So they built a rectenna with a waveguide.

Rectennas [wikipedia.org] have been around for decades, and 82% efficiency [ieee.org] (DC watts out / microwave watts into antenna) has been achieved. So 37% is nothing to be excited about.

If you hook up two long wires or plates to a diode, any RF in the vicinity will produce some DC across the diode. This is the principle behind "crystal radios". The problem is that you need big antennas to get much power from ambient RF.

Re:For $4, you can read the paper (4, Interesting)

hubie (108345) | about 8 months ago | (#45372875)

Actually, the difference here is that they built a rectenna out of metamaterials, specifically a split-ring resonator (SRR) design. I presume their point here is that they came up with a compact rectenna design that can work fairly well at 900 MHz. The paper you referenced with the 82% efficiency used a dipole antenna for 5.8 GHz. The wavelength at 5.8 GHz is something like 50 mm, and they used a 1/2 wave dipole antenna (their length was around 25 mm). The wavelength at 900 MHz is 333 mm, but their SRR design was only 40 mm on a side (a 1/2 wave dipole would have to be 150 mm or so).

I don't think they were making any claims of new physics here, but probably pointing out a design that would be fairly compact and leverage all the 900 MHz EMI flying around. For what its worth, their max efficiency occurred for a resistive load of 70 Ohms, which is a reasonable load for something that you want to power with an energy harvester.

Amps? (1)

k31bang (672440) | about 8 months ago | (#45372393)

How many amps are we talking about?

Re:Amps? (3, Funny)

Anonymous Coward | about 8 months ago | (#45372425)

Approximately zero.

Re:Amps? (0)

Anonymous Coward | about 8 months ago | (#45372699)

Is that amps of power or distance?

Re:Amps? (1)

thephydes (727739) | about 8 months ago | (#45372757)

It's amps of coulombs you dolt!

Re:Amps? (1)

Megane (129182) | about 8 months ago | (#45372993)

How many parsecs will it take to charge my phone?

Re:Amps? (1)

Nethemas the Great (909900) | about 8 months ago | (#45373011)

An inconsequential amount. I suspect a 20mA @3.2V LED [alldatasheet.com] would probably look similar to the one in the photo.

Grad students (2)

Optimal Cynic (2886377) | about 8 months ago | (#45372451)

This is why idiotic grad student posters shouldn't be shown to over enthusiastic marketing types.

Cell phones? (4, Interesting)

Okian Warrior (537106) | about 8 months ago | (#45372467)

The FCC limits wireless access point RF power to 1 watt.

From the image, I would guess that the metal thingy is 2 feet square, or about 1/3 square meter. I can't tell from the image whether the capture aperture is the profile or the end of the wedge, but let's give it the benefit of the doubt.

Standing 10 meters from a WAP is a sphere with area 4*M_PI*R^2 = 1256 m^2. A 1/3 meter capture aperture would eclipse 0.3/1256 of this, for about 240 microwatts. At 37% efficiency, that's about 80 microwatts. (Am I doing this right?)

Maybe possibly this could power micropower sensors (note: with a 2-foot square antenna on each one).

But a cell phone?

Re:Cell phones? (1)

hubie (108345) | about 8 months ago | (#45372925)

What you are looking at in the picture is the waveguide they used to test it. The antenna itself is inside the waveguide and is a split ring resonator, 40 mm on a side.

Sounds like PREECharge? (0)

Anonymous Coward | about 8 months ago | (#45372473)

How does this differ from what was invented at UTSA 2 years ago? http://www.energy-daily.com/reports/GoSolarUSA_Funds_Development_Of_PREEcharge_For_iPAD_And_Kindle_999.html

radiation too? (1)

Gravis Zero (934156) | about 8 months ago | (#45372479)

if they can modify this a little bit to absorb nuclear radiation, cosmic rays or universal radiation then they may have invented one of the greatest energy technologies since the solar panel.

- being able to clean up nuclear radiation would be great to avoid a "permanent" wasteland. then again, it brings the option of using nukes back on the table.
- absorbing cosmic rays could make space travel safer and possibly satellites lighter.
- if you can absorb universal radiation then you have a solar panel that always has sunlight.

i really hope this tech can be modified. there is a lot of potential for good.

Re:radiation too? (0)

Anonymous Coward | about 8 months ago | (#45372865)

No.
A "little bit" of modification will not make this able to clean up nuclear radiation.
Universal radiation? Like the cosmic microwave background radiation or what?

Re:radiation too? (3, Insightful)

Entropius (188861) | about 8 months ago | (#45372867)

Nuclear radiation doesn't work that way. We have gizmos that turn nuclear radiation into power; they're called radiothermal generators, and work by absorbing the radiation with some material that heats up, then capturing the thermal energy as it flows across a Peltier junction. We power spacecraft with 'em.

But this doesn't make the plutonium less radioactive any faster. Those plutonium nuclei are still going to take their sweet time decaying.

Nuclear power plants take advantage of this, too; heat in the reactor core is heat in the reactor core, and it doesn't matter whether it comes from fission directly or from secondary decay of fission products. But we can't do anything magic to fission products to make them decay into something stable any faster; eventually they get far enough down the decay chain to something long-lived enough that it's not worth trying to harvest the heat they release any more.

Re:radiation too? (2)

Carnildo (712617) | about 8 months ago | (#45373165)

But we can't do anything magic to fission products to make them decay into something stable any faster

Actually, we can. Neutron bombardment will usually create particles that are less stable, so they take a faster decay chain down to a stable state. It's a tradeoff: your radioactive waste becomes more radioactive, but for less time.

Re:radiation too? (1)

rubycodez (864176) | about 8 months ago | (#45372899)

Absorbing nuclear radiation and making electricity is a done deal, see your local nuclear power plant or talk to RPG generator manufacturer for a couple different methods.

Cosmic ray to electricity is pretty trivial too, what with a cosmic ray being a charged particle (usually proton) and all....

This signal followed me home - can I keep it? (3, Funny)

mwehle (2491950) | about 8 months ago | (#45372511)

Engineers at Duke University say they've constructed a device that can collect stray wireless signals

WTF is a "stray wireless signal"? This is a signal without an owner? Slipped out of its collar?

ctv (0)

Anonymous Coward | about 8 months ago | (#45372525)

Has anyone come up with a device that would let me take the 90v or so coming from the
cable companies coax cord and use it for charging, powering something in my home?

Re:ctv (1)

rubycodez (864176) | about 8 months ago | (#45372917)

answer is "yes". legality is "no". damaging gear not your own is "likely yes". getting fined or prosecuted is "possible".

Does this kill reception of wifi? cell? radio? (1)

DutchUncle (826473) | about 8 months ago | (#45372577)

Those "stray wireless signals" may well be doing something useful.

Looks to me like a somple Yagi antenna... (1)

hAckz0r (989977) | about 8 months ago | (#45372583)

Looks to me like a simple Yagi antenna inside of a waveguide. Inside a waveguide, and for an optimum tuned Yagi, the signal would have to be directionally pointed at this setup. Its not like you are going to snag some arbitrary signal that isn't pointed in your general direction. Perhaps if you are eating lunch on a picnic table while standing in front of a microwave repeater, you might be able to charge your cell phone. But then you needed to carry this rig with you while the extra battery option would clearly take less space. Maybe if it cam in an inflatable bubble with mylar deflectors it could be small enough to be practice? If you are not mobile then what is the use case for this?

Looks like someone didn't warn them... (0)

Anonymous Coward | about 8 months ago | (#45372613)

How utterly little power is available from stray RF. It would make a trickle charger look like a deluge.
But you can keep your watch batteries, or something.

Tesla did it already. (0)

Anonymous Coward | about 8 months ago | (#45372637)

And we shot that down. Because how can you bill people for it.

Re:Tesla did it already. (1)

rubycodez (864176) | about 8 months ago | (#45372933)

no, shot down because stupidly inefficient. not to mention the dangerous to those near the transmitter but back then who gave a shit.

Not enough energy, missing the point! (5, Interesting)

foxalopex (522681) | about 8 months ago | (#45372863)

This doesn't even pass the common sense logic rules if you understand physics. The issue is there's not much energy in these types of radio waves. A cellphone transmits a maximum of around 1 watts, a wifi router 50 milliwatts if you're lucky. By the time the radio waves have reached you their effective power has already dissipated by the square of the distance. Sure you might get a voltage potential that's in the 7 volt range but how's that useful if there's next to no current to do anything. Short of standing under a high voltage power line or next to some high power transmitter which probably wouldn't be safe for your health, this isn't going to work.

People also misunderstand Tesla's work. Tesla's work wasn't that you could just pop up an antenna and get free power. His plans involved putting up a massive transmission tower that would dump power into the air at an efficient frequency. A coil and antenna could then be used to pick up this power wirelessly. Great idea but the issue then is how exactly would you charge for this power when anyone with some know how could build a receiver to grab the "free" power?

Re:Not enough energy, missing the point! (2)

Animats (122034) | about 8 months ago | (#45373005)

Tesla's work wasn't that you could just pop up an antenna and get free power. His plans involved putting up a massive transmission tower that would dump power into the air at an efficient frequency. A coil and antenna could then be used to pick up this power wirelessly.

Right. When you read his plans, he's taking about a system where a small town is powered by a massive transmitter, each attic is full of antennas, and each house gets one (1) 40-watt light bulb.

Rocket Radio / Maxwell's Daemon (0)

Anonymous Coward | about 8 months ago | (#45372927)

Looks like they just re-invented the Rocket Radio [crystalradio.net] from the 1950's (radio receiver needing no battery, extracts its energy from the received transmission directly).

I'm wondering if this kind of thing is an example of Maxwell's demon [wikipedia.org] , the diode extracting useful energy from background EM radiation, any thoughts?

*sigh* (0)

Anonymous Coward | about 8 months ago | (#45372941)

What a bunch of idiots... Marketing people should not be allowed to roam the halls at cut-rate engineering schools. The result is hype over idiotic bullshit like this.

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