Harvesting electricity from “wasted” radio waves

posted at 6:31 pm on November 10, 2013 by Steve Eggleston

Beaming electricity into homes without wires has been a dream since the days of Nikolai Tesla. The Daily Mail reports researchers at Duke University have made a breakthrough on the efficiency of turning otherwise-wasted radio waves into electricity:

Engineers at Duke University have designed a breakthrough gadget that ‘harvests’ background microwave radiation and converts it into electricity, with the same efficiency as solar panels.

The development, unveiled on Thursday, raises exciting possibilities such as recharging a phone wirelessly and providing power to remote locations that can’t access conventional electricity.

And the researchers say that their inexpensive invention is remarkably versatile. It could be used to capture ‘lost’ energy from a range of sources such as satellite transmissions, sound signals or Wi-Fi….

They say the device harvested microwaves with an efficiency of 36.8 percent, similar to modern solar cells that capture light energy.

A report that will appear in the journal Applied Physics Letters in December states that this invention is capable of converting microwave signals to enough direct current voltage to recharge a cell phone battery.

The principle itself is sound. Indeed, every radio receiver converts the radio waves it receives into electricity. The Duke researchers did nearly quadruple the previous efficiency of converting radio waves into DC power.

However, the math does not quite work out yet. At its peak efficiency, the 5-cell device pictured as the thumbnail (picture courtesy Duke University) provides 7.3 volts across a load of 70-80 ohms. That translates to approximately 100 milliamps, and about 750 milliwatts. While that is the same as one unit load in the USB 3.0 definitions, and 1.5 times one unit load in the USB 2.0 definitions, that is far less than what a typical cell-phone charger provides.

To get that 750 milliwatts, they pumped a bit over 2 watts of radiofrequency energy at the space their device occupied. That was helped with a rather sizable waveguide. In contrast, wi-fi signals received by the average laptop receive somewhere around 10 picowatts, or 1/100,000,000,000th of a watt, and GPS signals received by a GPS receiver are a couple orders of magnitude weaker than that, though neither a laptop nor a GPS receiver are usually placed inside of a waveguide.

I somehow doubt the FCC would allow even a directional RF generator powerful enough to allow a long-distance version of the wireless charging pad. With that said, there looks to be a very practical use for this breakthrough – a radio communications system that uses less power for the same range.

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Glad to see you posting threads again, Egg…

OmahaConservative on November 10, 2013 at 6:35 PM

This is not so much a breakthrough for generating energy as it is a breakthrough for generating hype that leads to government “investment”.

pedestrian on November 10, 2013 at 6:37 PM

Keith Dolbermann, Ed Schulz, Chrissy Matthews, MSLSD, CNN, Public Brainwashing System, NPR, NBC, See-BS, ABC, Al-Gore Jazeera, etc.

There’s lots of wasted radio waves to reclaim.

viking01 on November 10, 2013 at 6:42 PM

Never mind this small potatoes stuff as almost unlimited energy could be available if Obama’s lies could be harvested and turned into energy.

VorDaj on November 10, 2013 at 6:44 PM

This is not so much a breakthrough for generating energy as it is a breakthrough for generating hype that leads to government “investment”.

pedestrian on November 10, 2013 at 6:37 PM

Ding ding ding

Rio Linda Refugee on November 10, 2013 at 6:45 PM

To get that 750 milliwatts, they pumped a bit over 2 watts of radiofrequency energy at the space their device occupied. That was helped with a rather sizable waveguide. In contrast, wi-fi signals received by the average laptop receive somewhere around 10 picowatts, or 1/100,000,000,000th of a watt, and GPS signals received by a GPS receiver are a couple orders of magnitude weaker than that, though neither a laptop nor a GPS receiver are usually placed inside of a waveguide.

Hello captain obvious.

SparkPlug on November 10, 2013 at 6:47 PM

Nikolai Tesla

Just so you know, it’s Nicola Tesla, no “i” at the end. He was Serbian, not Russian.

bgoldman on November 10, 2013 at 6:50 PM

Keith Dolbermann, Ed Schulz, Chrissy Matthews, MSLSD, CNN, Public Brainwashing System, NPR, NBC, See-BS, ABC, Al-Gore Jazeera, etc.

There’s lots of wasted radio waves to reclaim.

viking01 on November 10, 2013 at 6:42 PM

You forgot Dan Blather.

“Kenneth, what is the frequency?”

Del Dolemonte on November 10, 2013 at 6:52 PM

I recall that the method proposed for getting electricity down to Earth from orbiting solar-power collecting satellites was by microwave transmission – so this should be nothing new. Maybe in terms of the intensity of the radiation gathered, but the concept should be the same.

sultanp on November 10, 2013 at 6:55 PM

Pipe dream…

It would make more sense to ban NPR….

Attack waste at the source..

Electrongod on November 10, 2013 at 6:59 PM

I like the idea, but get back to me it, solar and wind are as efficient as proven methods of generating power.

OldEnglish on November 10, 2013 at 7:05 PM

Keith Dolbermann, Ed Schulz, Chrissy Matthews, MSLSD, CNN, Public Brainwashing System, NPR, NBC, See-BS, ABC, Al-Gore Jazeera, etc.

There’s lots of wasted radio waves to reclaim.

viking01 on November 10, 2013 at 6:42 PM

…lol!

It would make more sense to ban NPR….

Attack waste at the source..

Electrongod on November 10, 2013 at 6:59 PM

…and do what Electrongod suggests…to all of them!

KOOLAID2 on November 10, 2013 at 7:05 PM

OldEnglish on November 10, 2013 at 7:05 PM

when it …

OldEnglish on November 10, 2013 at 7:11 PM

O/T: Was out walking about today… spotted all black wooly-worms.

Hope y’all are ready for what’s coming.

CPT. Charles on November 10, 2013 at 7:12 PM

Harris Faulkner is sure beautiful…

OmahaConservative on November 10, 2013 at 7:13 PM

CPT. Charles on November 10, 2013 at 7:12 PM

I’m not ready. What is coming? Those worms?

SparkPlug on November 10, 2013 at 7:28 PM

Just so you know, it’s Nicola Tesla, no “i” at the end. He was Serbian, not Russian.

bgoldman on November 10, 2013 at 6:50 PM

Croatian actually. Not much of a big deal to us Americans, but to those in the Balkans, WHOOO HEE! Calling him Serbian would be killing words! I’ve never seen as much “racial” hatred as I saw in that part of the world. Usually calm, intelligent human beings turned into venomous animals when speaking about the “other side.”

NavyMustang on November 10, 2013 at 7:30 PM

Bloomberg is banning any waves larger than 32 hertz

faraway on November 10, 2013 at 7:30 PM

Wiki says both his parents were ‘Serbian Orthodox priests’.

faraway on November 10, 2013 at 7:32 PM

BBC

Tesla, an ethnic Serb

Replying to a telegram written to him by a Croatian, Tesla wrote that he was equally proud of his Serbian ethnicity and his Croatian birthplace; because at the time Serbia and Croatia were unified as a single kingdom.”

faraway on November 10, 2013 at 7:34 PM

We could have unlimited energy if someone could figure out how to harvest Dem/RINO-voters’ wasted brain waves — even as low-wattage as each individual’s is …

ShainS on November 10, 2013 at 7:37 PM

SparkPlug on November 10, 2013 at 7:28 PM

Wooly worms are a ‘folklore’ predictor of the coming winter.

CPT. Charles on November 10, 2013 at 7:40 PM

Shouldn’t be patentable, getting power from broadcast signals is old, very old art. Google “crystal radio with antenna powered amplifier” , or click examples — http://hibp.ecse.rpi.edu/~john/xtal.html or http://www.oldradioworld.de/gollum/dt.htm

htom on November 10, 2013 at 7:45 PM

Somebody changed the thumbnail on me. Whoops.

Steve Eggleston on November 10, 2013 at 7:59 PM

O/T: Was out walking about today… spotted all black wooly-worms.

Hope y’all are ready for what’s coming.

CPT. Charles on November 10, 2013 at 7:12 PM

But where they traveling right to left or left to right?

davidk on November 10, 2013 at 8:01 PM

This is not so much a breakthrough for generating energy as it is a breakthrough for generating hype that leads to government “investment”.

pedestrian on November 10, 2013 at 6:37 PM

Actually, this was a DoD-funded project.

Steve Eggleston on November 10, 2013 at 8:03 PM

Shouldn’t be patentable, getting power from broadcast signals is old, very old art. Google “crystal radio with antenna powered amplifier” , or click examples — http://hibp.ecse.rpi.edu/~john/xtal.html or http://www.oldradioworld.de/gollum/dt.htm

htom on November 10, 2013 at 7:45 PM

Crystal radios produce a very tiny bit of (AC) power, just enough to power a single speaker at a very low volume or a second crystal radio to pick up a more-distant station, with a rather large antenna.

What might be patentable are the method and materials to make that concept as efficient as it is.

Steve Eggleston on November 10, 2013 at 8:19 PM

I recall that the method proposed for getting electricity down to Earth from orbiting solar-power collecting satellites was by microwave transmission – so this should be nothing new. Maybe in terms of the intensity of the radiation gathered, but the concept should be the same.

sultanp on November 10, 2013 at 6:55 PM

Yep, same principle. This breakthrough could easily be used to make that method more efficient, perhaps eventually to the point of making it feasible from a cost perspective.

Steve Eggleston on November 10, 2013 at 8:25 PM

Crystal radios produce a very tiny bit of (AC) power, just enough to power a single speaker at a very low volume or a second crystal radio to pick up a more-distant station, with a rather large antenna.

What might be patentable are the method and materials to make that concept as efficient as it is.

Steve Eggleston on November 10, 2013 at 8:19 PM

Try this. Take a single fluorescent tube out to the switchyard of a large power plant at night. Find a high voltage overhead line, say 500kv or so, That’s relatively close to the ground. Hold the tube up over your head and watch what happens. Don’t be afraid :-)

Oldnuke on November 10, 2013 at 8:27 PM

bgoldman on November 10, 2013 at 6:50 PM

My bad, bgoldman! You’re right. Tesla was an ethnic Serb born in Croatia. Next time I’ll check the biography I have of him BEFORE I stick my foot in it! My apologies.

NavyMustang on November 10, 2013 at 8:29 PM

Intelligence agencies used to use battery-powered radio-transmitter bugging devices concealed in walls, furniture, etc, to eavesdrop on people.

One trick to stretch out their battery life was used at night when there really wasn’t anything “interesting” to listen to. The buggers would switch their transceiver that was tuned to the bug and send out a steady “hum” at medium Hz on the bug’s freq. This would feed back through the bug’s circuitry to the battery, and by conversion recharge the battery, albeit only partly and at lower amperage.

Known as “trickle charging”, it wouldn’t help if the battery was flat or nearly so, but as long as it held a decent charge the procedure could extend its life and thus the useful life of the bug.

Probably the ultimate expression of this was the gadget the KGB put in the new U.S. Embassy in Moscow in the late Fifties. A two-foot bronze plaque of the Great Seal was attached to the wall of the conference room. Inside, it was a resonant cavity shaped to respond to microwave emissions. When a microwave beam was turned on it from across the street, it acted exactly like the diaphragm mike in the mouthpiece of a telephone handset. No “internal” power required, which meant that it took over a year for it to be discovered, because it had no batteries, etc., for potentiometers and such to detect during “sweeps”.

In short, if all you want is low wattage, low voltage, and low amperage, this will probably work. For anything other than that, not so much unless you want to go to the lengths Tesla did at Wardenclyffe.

clear ether

eon

eon on November 10, 2013 at 8:31 PM

Harvesting electricity from “wasted” radio waves

This completely impractical fantasy uses the same thought process by which Liberals try to replace real coal, oil, and nuclear energy sources with windmills, solar cells, and unicorn farts.

The progression is a familiar one:

1. Some liberal with no experience and little or no actual knowledge of the subject declares that he has made a fantastic discovery. MSM tools write puff pieces, never doing a real investigation.

2. All those with actual experience and actual knowledge are slandered as “naysayers” and/or “tools of evil corporations”

3. Liberal gangs of know-nothings are assembled into rent-seeking organizations who lobby government for grants, exemptions from regulations, and government subsidies.

4. After wasting billions of taxpayer funds, some kind of disaster befalls the “new technology” company: exposing it as impotent, fraudulent, and/or dysfunctional.

5. Liberals scatter, money disappears. Real people are hurt.

6. Even though the entire venture has been a monumental failure, the original Liberal gets praised and publicly receives award from mindless celebrity dolts for his “work in the ____ industry.”

landlines on November 10, 2013 at 8:31 PM

Why not a device that converts noise into electricity?

We could put ‘sonic collectors’ at really deafening and cacaphonous spots and ‘harvest’ the gratis power.

The demo model installed at the base of Niagara Falls, to start.

And the next collector in front of Obama’s mouth… if there is a teleprompter in sight. His standard hour of fatuous blather could power a modest arugula farm.

If we could ever harness Political Lies we would achieve virtual perpetual free power.

profitsbeard on November 10, 2013 at 8:35 PM

htom on November 10, 2013 at 7:45 PM

Used to make them during WWII. Used them to try picking up RAF chatter.

OldEnglish on November 10, 2013 at 8:35 PM

Try this. Take a single fluorescent tube out to the switchyard of a large power plant at night. Find a high voltage overhead line, say 500kv or so, That’s relatively close to the ground. Hold the tube up over your head and watch what happens. Don’t be afraid :-)

Oldnuke on November 10, 2013 at 8:27 PM

Don’t be afraid…until the police show up wondering what that light is. If you’re lucky, they’ll know the concept. If you’re unlucky,….

Steve Eggleston on November 10, 2013 at 8:41 PM

If we could ever harness Political Lies we would achieve virtual perpetual free power.

profitsbeard on November 10, 2013 at 8:35 PM

Unfortunately, this power source is already employed stoking the fires of Hell.

landlines on November 10, 2013 at 8:48 PM

There are a lot of low-energy power sources in the environment. You could use piezo-electric converters to get waste heat to turn to electricity, solar cells for light energy, and radio-frequency converters for stray RF harvesting.

And all of it still wouldn’t be enough to light a dozen fireflies. The problem with all of these “free” sources is lack of density. It’s out there, but it requires a huge collector and expensive converter to make any useful amount of power. Has anyone looked at the number of solar panels required to power a single typical US household? A single wind turbine with 75 foot blades can power about 250 houses, but the converter and monitor involved is millions of dollars (and they break and require maintenance); bats and eagles have a very low win-loss ratio when battling them.

Such a converter as in the article would require a receiver about the size of Wyoming to power a small city.

Oh, dang it! I take no responsibility for any executive orders turning all Wyoming land into the “Federal Stray RF Accumulator and Converter Project.”

Wino on November 10, 2013 at 8:57 PM

OK, but when can I buy a Romulan disruptor?

Ronnie on November 10, 2013 at 10:01 PM

Nikola with a k

rightside on November 10, 2013 at 10:04 PM

I believe this has been around in principle for a long time. I remember watching a Cold War documentary (I don’t remember who was actively spying on who) where they embedded a similar device in a carved wooden emblem that hung behind a diplomat in his office. It avoided detection in bug sweeps because it didn’t give off any signal or any form of residual electricity until the spies aimed a highly directionalized radio wave at the bug, which gave the listening device its power. With no transmissions when not in use or any batteries or tapes to change, the device went undetected for several years, as I remember.

Glenn Jericho on November 10, 2013 at 10:08 PM

Don’t be afraid…until the police show up wondering what that light is. If you’re lucky, they’ll know the concept. If you’re unlucky,….

Steve Eggleston on November 10, 2013 at 8:41 PM

Heh, cops aren’t going to show up, at least they never did for me. Of course I had a key to the switchyard and a valid reason for being there. The first time I saw the fluorescent tube light up in mid air it did sort of freak me out, even though I knew what to expect. We used to do it as a training exercise for people qualifying for swithchyard operations. It never got old and it never failed to impress.

Oldnuke on November 10, 2013 at 10:11 PM

Steve Eggleston on November 10, 2013 at 8:41 PM

One thing I did see in my career that scared the crap out of me. A 21.5kv to 500kv main transformer exploding. That’ll get your attention.

Oldnuke on November 10, 2013 at 10:18 PM

One thing I did see in my career that scared the crap out of me. A 21.5kv to 500kv main transformer exploding. That’ll get your attention.

Oldnuke on November 10, 2013 at 10:18 PM

That will definitely get your attention.

Steve Eggleston on November 10, 2013 at 10:46 PM

with the same efficiency as solar panels.

I may have found the weakness…..

There Goes the Neighborhood on November 10, 2013 at 11:16 PM

Something like this could finally provide a benefit to living by high-voltage transmission towers. Of course the power companies would probably look for collection devices and try to block them or charge you for stealing their EMFs. (Cancer is free, but generating power will cost you!)

Marcola on November 11, 2013 at 12:53 AM

O/T: Was out walking about today… spotted all black wooly-worms.

Hope y’all are ready for what’s coming.

CPT. Charles on November 10, 2013 at 7:12 PM

Can we make friends with them?!

The Nerve on November 11, 2013 at 1:30 AM

O/T: Was out walking about today… spotted all black wooly-worms.

Hope y’all are ready for what’s coming.

CPT. Charles on November 10, 2013 at 7:12 PM

Al Gore?

apostic on November 11, 2013 at 4:44 AM

Steve, methinks they were being a little optimistic when they talked about power from the current breed of satellites. However, there has been, for decades now, a push towards solar power installations on orbit large enough to beam power down to Earth. For a very long time, ever since I was asked to make a feasibility study on the concept in the 70s, I’ve had a giant urge to be on some other planet when power was beamed down from orbit to the Earth at levels that allowed efficient harvesting. This only changes my objection by a modest percentage. Not only does the energy need to be converted from microwaves to DC efficiently but it also must be transported to a collection point efficiently. That can get ugly with wire losses.

Sit down and define for yourself, or use FCC definitions, a safe microwave power density. Then from that calculate an antenna area sufficient to recover a city’s worth of electricity from that area. Multiply by some efficiency factors to get an even larger area. If you come up with reasonable numbers then you’ve found the use for this tool Dartmouth has produced.

Now figure “what could possibly go wrong?” Suppose the beam from the antenna is somehow diverted to another area, perhaps aimed
directly at the city it’s servicing. Would you want to be in that city?

{^_^}

herself on November 11, 2013 at 4:55 AM

Let me know when they get cheap enough to use as house siding.

Until then, In O’bozo’s America, it’s a copper roof and aluminum foil under the tyvek

WryTrvllr on November 11, 2013 at 5:04 AM

nathor on November 10, 2013 at 7:13 AM

If memory serves this was calculated by a group at Princeton in the 1960′s by Gerard K. O’Neil and published in the way to colonize space in High Frontier. Remember this was done using 1960′s tech as its basis and the microwave density they were looking at was 2x that of what any square patch of land received from the sun. The idea was that orbital collectors would beam low density microwaves down to an antenna array stretching out over acres, and as it isn’t much more than metal posts in the ground regularly spaced, you could also farm the same land as 2x solar microwave energy isn’t that much. Fly in a jetliner and you get more than that during daytime flights. If the beam wandered off target you don’t get cooking but, at most, some very mild warming of anything that can absorb the frequencies involved: if you aren’t cooked during a daytime jet flight, neither would anything under the beam.

The idea was that producing Solar Power Satellites would be done utilizing a lofted space factory and lunar mining system (robotocized most likely) that would just scoop regolith into containers that could be sent down a maglev accelerator and sent to a retrieving station in Earth orbit. The first job of the factory was to make a habitat (a relatively simple one) for the few people to work up there, then produce a couple of SPS’s for income, then produce a copy of itself. With two factories you can then dedicate one to SPS production, while the other sends a second scoop operation back to the moon… after that you can add more living space, create SPS’s or make another copy of the factory…the then expected cost of energy utilized on the ground with all forms of loss included was 1 center/kWh circa 1972 I think it was when the work was revised for first publication.

Basically as the Lunar regolith is a general mixture of undifferentiated ores and elements, any cubic meter of it has a generally well known quantity of each of the elements. That is because it is ejecta fall back from meteor and other external impacts. At some point you would want a Lunar colony, a larger space habitat that can be spun for artificial gravity, and so on… but the general idea is to mine the moon to create a new economic base on the cheap. The price tag was far less than the Apollo project and might now fit within the budgets of a first large scale private space project due to advances in automation and technology… with minor advances in rocketry. Do as much of this via automated or semi-automated or ROV systems as you can, and the price falls even more.

Environmentalists should welcome space habitation as it will move the industrial base of planet Earth into orbit and off the planetary surface. Cheap energy harvested by square miles of collector platforms then becomes available for beaming down to anyone with a decent sized array and willing to pay the cost to get a satellite to beam it to them. The cost is an inverse of the scale of the system up to the point of maximum number of collectors in Earth’s orbit around the sun… which is huge, BTW, once you start considering reflectors and re-broadcast satellites in other parts of Earth’s orbit around the sun.

The stuff seen by these fine technical innovators isn’t all that new or exciting. And if you are in a middle of a cornfield someplace with no real nearby broadcast stations or getting much in the way of continuous satellite transmission of anything, then you are pretty much SOL. The best way, the cheapest way, the fastest way to get permanent energy harvesting is to get out from under the atmosphere and into space. That is a game changer for humanity and we have been on the cusp of it since the 1960′s… Progressives have been trying to drag us back into their lovely world that is stuck on the planetary surface so they can complain about, not get off this rock and actually start raising our eyes to the eternal horizon.

ajacksonian on November 11, 2013 at 7:06 AM

O/T: Was out walking about today… spotted all black wooly-worms.

Hope y’all are ready for what’s coming.

CPT. Charles on November 10, 2013 at 7:12 PM

I, for one, welcome our wooly overlords.

crash72 on November 11, 2013 at 7:34 AM

I was told there’d be no math on this exam.

tlynch001 on November 11, 2013 at 7:59 AM

Goodie, another green power that’s gonna save us all from agw. Bet Duke gets this figured out before the website is fixed.

Kissmygrits on November 11, 2013 at 8:23 AM

I had hoped they discovered subspace radio transmission (a la Star Trek)–have they?

ParisParamus on November 11, 2013 at 8:31 AM

I was just researching the Hendershot Generator this last weekend. A buddy who wishes to be off-grid was interested and stopped by to talk about it. There is little info on how it works but from looking at the circuit it seems to be tapping the same EM pollution that this claims to. That said, just looking at the device screams hoax.

Dr. Frank Enstine on November 11, 2013 at 8:48 AM

Hmm. Rusty, but I think if you significantly scale-up this concept there will be an increased inductive and/or capacitive load reflected back on the devices generating this ‘wasted’ energy. Requiring them to be supplied with … more energy.

No free lunch?

Tsar of Earth on November 11, 2013 at 9:24 AM

NavyMustang on November 10, 2013 at 7:30 PM

Oh yes, the one Serb in Srebrenecia got quite passionate about how wrong my Berlitz book was because it was titled “Serbo-Croatian”.

GWB on November 11, 2013 at 10:29 AM

It’s called a rectenna and was invented in 1964; patented in 1969.

RedManBlueState on November 11, 2013 at 12:40 PM