Harvesting energy from electromagnetic waves

April 14, 2015
The metasurface used for collecting electromagnetic energy is shown. Credit: O.Ramahi/U.Waterloo

For our modern, technologically-advanced society, in which technology has become the solution to a myriad of challenges, energy is critical not only for growth but also, more importantly, survival. The sun is an abundant and practically infinite source of energy, so researchers around the world are racing to create novel approaches to "harvest" clean energy from the sun or transfer that energy to other sources.

This week in the journal Applied Physics Letters, from AIP Publishing, researchers from the University of Waterloo in Canada report a novel design for harvesting based on the "full absorption concept." This involves the use of metamaterials that can be tailored to produce media that neither reflects nor transmits any power—enabling full absorption of incident waves at a specific range of frequencies and polarizations.

"The growing demand for around the globe is the main factor driving our research," said Thamer Almoneef, a Ph.D. student. "More than 80 percent of our today comes from burning fossil fuels, which is both harmful to our environment and unsustainable as well. In our group, we're trying to help solve the energy crisis by improving the efficiency of electromagnetic systems."

Since the inception of collecting and harvesting electromagnetic energy, classical dipole patch antennas have been used. "Now, our technology introduces 'metasurfaces' that are much better energy collectors than classical antennas," explained Omar M. Ramahi, professor of electrical and computer engineering.

Metasurfaces are formed by etching the surface of a material with an elegant pattern of periodic shapes. The particular dimensions of these patterns and their proximity to each other can be tuned to provide "near-unity" energy absorption. This energy is then channeled to a load through a conducting path that connects the metasurface to a ground plane.

The key significance of the researchers' work is that it demonstrates for the first time that it's possible to collect essentially all of the electromagnetic energy that falls onto a surface.

"Conventional antennas can channel electromagnetic energy to a load—but at much lower energy absorption efficiency levels," said Ramahi. "We can also channel the absorbed energy into a load, rather than having the energy dissipate in the material as was done in previous works."

As you can imagine, this work has a broad range of applications. Among the most important is , an emerging critical technology that can significantly help to address energy shortages. It converts solar rays into microwaves—using conventional photovoltaic solar panels—and then beams the microwave's energy to microwave collector farms at designated locations on Earth. Japan is way out in front of rest of the world in this realm, with plans to begin harvesting solar power from space by 2030.

"Our research enables significantly higher energy absorption than classical antennas," Ramahi said. "This results in a significant reduction of the energy harvesting surface footprint. Real estate is a precious commodity for —whether it's wind, hydro, solar or electromagnetic energy."

Other key applications include "wireless power transfer—directly adaptable to power remote devices such as RFID devices and tags or even remote devices in general," Ramahi noted.

The technology can also be extended to the infrared and visible spectra. "We've already extended our work into the infrared frequency regime and we hope to report very soon about near-unity absorption in those higher-frequency regimes," added Ramahi.

Explore further: Video: Solar power from energy-harvesting trees

More information: "Metamaterial electromagnetic energy harvester with near unity efficiency," by Thamer S. Almoneef and Omar M. Ramahi, Applied Physics Letters on April 14, 2015. DOI: 10.1063/1.4916232

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42 comments

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gkam
1.6 / 5 (5) Apr 14, 2015
Oh, I was hoping to use a series of different length dipoles with diodes would be used to collect the EM smog in which we live. This is much better.

But a standard antenna is not a big energy producer. We usually set radio signal strength to break squelch at 3 microvolts.

24volts
3 / 5 (1) Apr 14, 2015
Seems like I remember someone doing this a couple of years ago with the light antenna stuff. If I remember correctly the antennas worked fine but they were having trouble trying to get the received power out of the antenna's to an actual circuit... Have these people solved that problem? It didn't seem to say in the article.
Sonhouse
3 / 5 (3) Apr 14, 2015
Gkam, are you a ham? Squelch level is one parameter of our 2 meter and higher frequencies for handy talkies.What I was wondering if this technology could be adopted to 2 meter and higher frequencies and whether that kind of technology used as a transmit and receive antenna would have more gain than say, a yagi of X amount of elements. The image they show is clearly for something like X band, 10 ish gigahertz waves and of course 2 meters is only 145 odd megahertz which would require a matrix some 70 times larger than the one they show.
The fact that they have some kind of printed circuit antenna says it is narrow frequency, low bandwidth so it would be a bit trickier to make these things wideband.
For solar to microwave conversion in orbit and then pickups on the ground you would want as high a Q as possible and tuned to a specific frequency, 10 gigahertz or 20 gigahertz, whatever gets through atmosphere the best. Higher frequencies would obviously mean smaller antenna's.
Liem
5 / 5 (1) Apr 14, 2015
Seems like I remember someone doing this a couple of years ago with the light antenna stuff. If I remember correctly the antennas worked fine but they were having trouble trying to get the received power out of the antenna's to an actual circuit... Have these people solved that problem? It didn't seem to say in the article.

It was about gold nanoantennas for infrared harvesting.. the problem at the time was that they could not have fast enought current rectifiers and I don`t think they have solved this problem yet.
adam_russell_9615
3 / 5 (2) Apr 14, 2015
The ocean is a huge solar energy collector. Water absorbs massive amount of energy, evaporates, makes clouds, water condenses to rain - releasing that energy into the atmosphere as heat. If we could instead find a way to harvest that energy from the clouds we would get:
1. huge energy resource
2. triggered rain when we want it (remove that energy and water MUST condense)
3. prevent that heat from going directly into the atmosphere adding to global warming.
TheGhostofOtto1923
4 / 5 (5) Apr 14, 2015
"The key significance of the researchers' work is that it demonstrates for the first time that it's possible to collect essentially all of the electromagnetic energy that falls onto a surface."

-Its still not a whole heck of a lot is it? What we need are entirely new sources of energy suitable for both powering robots indefinitely and desalinating enough water to supply california.

And these sources may be just around the corner.
http://www.e-catw...-iccf19/
http://www.blackl...ats-new/

-We had better hope that they are.
gkam
1 / 5 (4) Apr 14, 2015
Sonhouse, the three microvolts is the sensitivity we used in the service. I worked on ARC-27, ARC-34, ARC-51X/BX, FM-622, Wilcox 807, VHF-101, ARR-52, ARC-65, and ARC-58, a few I forgot, and the Collins 618 series from S-1 to the T, down to the Narco 1016 Sapphire for the General's U-3A.
allergg
not rated yet Apr 14, 2015
Does this mean that crystal radios will make a comback ? And could such a radio develop enough volume to be practical ?
peter_bilski
2 / 5 (2) Apr 15, 2015
I did try to read this article few times already and still don't have a clue how it is related to solar energy. What exactly range of waves this device is going to capture ?
Just saying , electromagnetic waves , quite a broad spectrum one may think about. (?)

PPihkala
4 / 5 (1) Apr 15, 2015
-Its still not a whole heck of a lot is it? What we need are entirely new sources of energy suitable for both powering robots indefinitely and desalinating enough water to supply california.

And these sources may be just around the corner.
http://www.e-catw...-iccf19/

-We had better hope that they are.


Those are nice, but they do not compare to what Solar Hydrogen Trends is doing with COP > 900: http://www.solarh...nds.com/ They appear to be fissioning oxygen from water to gain >0.9kg of hydrogen from 1kg of water. At room temperature.
antialias_physorg
not rated yet Apr 15, 2015
Have these people solved that problem?


From the linked abstract:
A metamaterial slab was designed comprising 13 × 13 electrically small cells, each loaded with an 82 Ω resistor which mimics the input impedance of a rectification circuitry. Unlike earlier designs of metamaterial absorbers, here the power absorption is mostly dissipated across a resistive load instead of the dielectric substrate. This implies that effective electromagnetic energy harvesting can be achieved. The power is channeled through a via connected to each cell. For a design optimized at 3 GHz, simulation and experimental results show power absorption efficiency of 97% and 93%, respectively.


A quick google found a 2.54 GHz rectifier with a 60% efficiency.
TheGhostofOtto1923
3.2 / 5 (6) Apr 16, 2015
Sonhouse, the three microvolts is the sensitivity we used in the service. I worked on ARC-27, ARC-34, ARC-51X/BX, FM-622, Wilcox 807, VHF-101, ARR-52, ARC-65, and ARC-58, a few I forgot, and the Collins 618 series from S-1 to the T, down to the Narco 1016 Sapphire for the General's U-3A.
Who cares? Nobody cares what you did in the service. Haven't you noticed? Too senile maybe?
http://youtu.be/inCC-PAggRA
http://youtu.be/ah5FEpGql9s
gkam
2.2 / 5 (6) Apr 16, 2015
You apparently do.

Do you dream of me at night?
ulao
not rated yet Apr 16, 2015
adam_russell_9615
3. prevent that heat from going directly into the atmosphere adding to global warming.

Sorry it doesn't work that way. Once the energy comes in it has to be dumped somewhere as heat unless you can somehow re-radiate back into space.
ulao
4.3 / 5 (3) Apr 16, 2015
TheGhostofOtto1923
ARC-27s. Man you do go back. We used those things in RAPCON in the 60s. They date back to the 40s.
gkam
1.4 / 5 (5) Apr 16, 2015
That was my post, and you are correct. We had those integrated with digiplexers, crypto, and and cards of integrated circuits, in 1967, for the Electronic Battlefield.
ulao
4 / 5 (1) Apr 16, 2015
Sorry bout that gkam.
gkam
1.8 / 5 (4) Apr 16, 2015
ulao, the ARC-27's were replaced in 1968 with the ARC-51X/BX.
gkam
1.8 / 5 (4) Apr 16, 2015
Jeez, ulao, the Flight Deck UHF control boxes were out on our Connie in 1967, coming back to Cape Cod from Florida, and I was in the radio op position dialing in the ARC-27 POS when RAPCON talked us in one night in a pea-soup fog, with the repeated transmission of "40 feet below Glide Slope" ringing in my ear.
ulao
5 / 5 (2) Apr 16, 2015
Thank God for God's chosen airmen (GCA). Eh? I was radar maintenance but I saw a few saves in my day.
ulao
5 / 5 (2) Apr 16, 2015
In particular I remember a VFR only private pilot who got himself into a fix above a solid cloud deck. GCA at Kincheloe tried several times to talk him down, every time he would be doing fine till he got to 1000 agl and would loose his nerve. Finally a T34 escorted him through a dutchmans breetches over Pelleston MI.
TheGhostofOtto1923
3.2 / 5 (6) Apr 17, 2015
Aw gkam found a friend. How sweet.
gkam
3 / 5 (6) Apr 17, 2015
Had otto done something in his life, he might have had one, too.

Pay attention, and you can learn something.
Da Schneib
5 / 5 (1) Apr 18, 2015
It didn't seem to say in the article.
Follow the link to the scholarly paper and read the abstract, even if you don't have the rights to read the whole article.

They got 93% of the power back, minimum, 97% commonly, and it appears they got it through resistors, feeding the power out through vias. Simple wiring, in other words. Maybe other folks were too involved in the surface features and forgot all their electronics.
Da Schneib
4 / 5 (1) Apr 18, 2015
What I was wondering if this technology could be adopted to 2 meter and higher frequencies and whether that kind of technology used as a transmit and receive antenna would have more gain than say, a yagi of X amount of elements. The image they show is clearly for something like X band, 10 ish gigahertz waves and of course 2 meters is only 145 odd megahertz which would require a matrix some 70 times larger than the one they show.
Kinda bulky to carry around. Oh, and 3GHz according to the literature.

contd
Da Schneib
5 / 5 (1) Apr 18, 2015
The fact that they have some kind of printed circuit antenna says it is narrow frequency, low bandwidth so it would be a bit trickier to make these things wideband.
Should be fine for microwave energy transfer from solar power satellites. The efficiency of the transfer has long been the biggest concern; even with low-efficiency satellites, you can still get more power than the microwave transmitters can handle. If you can get most of it, you can use low enough power in the beam that if it gets off target it won't fry anybody.

For solar to microwave conversion in orbit and then pickups on the ground you would want as high a Q as possible and tuned to a specific frequency, 10 gigahertz or 20 gigahertz, whatever gets through atmosphere the best. Higher frequencies would obviously mean smaller antenna's.
Yep. And with good efficiency in transmission, this is a very viable technology.
gkam
1 / 5 (3) Apr 19, 2015
You guys let them beam you.

Not me.
Da Schneib
1 / 5 (1) Apr 19, 2015
You'll get more standing in front of your microwave oven, Grace.
Returners
1 / 5 (1) Apr 19, 2015
The ocean is a huge solar energy collector. Water absorbs massive amount of energy, evaporates, makes clouds, water condenses to rain - releasing that energy into the atmosphere as heat. If we could instead find a way to harvest that energy from the clouds we would get:
1. huge energy resource
2. triggered rain when we want it (remove that energy and water MUST condense)
3. prevent that heat from going directly into the atmosphere adding to global warming.


You'd need collectors on the spot, which means gliders or balloons.

I've mentioned possible uses of balloons to accomplish this as they are more stable than gliders, and there are ways of doing this, I think, without causing too much use of Helium.

You'd want shaped balloons, like zeppelins but flatter instead I think, which have glider-like properties, but make use of bouyancy to maintain the majority of lift They'd carry EM collectors and send back power where needed or ferry people around.
gkam
1 / 5 (3) Apr 19, 2015
Let's beam this stuff down on a cold state, where they are snowed under for half of the year, then the tornadoes, then the Summer floods, then the terrible Winter again.

Let's be honest: A huge grid of PV panels in space with transmitters to send EM radiation down to Earth for power is REALLY dumb.

Energy harvesting on Earth, however is a great idea.
gkam
1 / 5 (3) Apr 19, 2015
Schneib, what is your gripe? I already identified myself, so otto could go sulk. I am George Kamburoff, "and not a mere device", to quote Thurber.

Sorry to irritate all of you, but what I said is real. Yeah, it is full of ridiculous experience, but true. I was hoping we could discuss it all, the real world, and compare and debate, but too many folk here are playing some kind of game. otto even crows about it, his "sock puppets", and the "games" he plays with others.

But I am here to learn and teach, too. Why are you folk here?
inorg_lsc
5 / 5 (1) Apr 19, 2015
There is still nothing like generation at the point of use (eg https://www.youtu...bcLVvPCY )
The way this is going now, we will enjoy more energy coming from advanced windows than from silicon on roofs, in a few years.
Da Schneib
1 / 5 (1) Apr 20, 2015
Well, I'm sure not here to listen to liars, Grace.

Why is it every time I come across another antitechnology nutjob, they turn out to be lying about their evidence?

Care to give some sort of reason for being against solar power satellites, Gracie? Afraid we're going to "pollute space?"
gkam
1 / 5 (3) Apr 20, 2015
Generation at point of use is exactly what is happening, but too many folk are stuck in the past. I had expected utilities to replace substations with natural gas-fired self-reforming fuel cells, making each neighborhood their own supplier, but connected to everyone else.

With PV the granularity goes down to the household. With energy harvesting, to the individual.
Da Schneib
1 / 5 (1) Apr 20, 2015
Forget something, Gracie?

Like, actually answering my question, for example?

Let me repeat it: why are you against solar power satellites, Gracie?

BTW, rating all my posts 1 when I'm not doing it to you is pretty transparent, wouldn't you say? So, vicious and vindictive much, Gracie? Just askin'.

Meanwhile, what's a "Research Engineer?" What *kind* of "Research Engineer" is that, precisely, Gracie?
Da Schneib
1 / 5 (1) Apr 20, 2015
They aren't handing out diplomas for "Research Engineers," Gracie.

Maybe you never noticed.
docile
Apr 20, 2015
This comment has been removed by a moderator.
Da Schneib
not rated yet Apr 20, 2015
I think this technology handles power transfer better than dielectric resonators. Sensitivity is not the issue here; efficiency is. Dielectric resonators are very sensitive receivers, but not very efficient; they're much more efficient as transmitters. Not only that but this technology trumps them in its cost. Antennae built to receive relatively high energy microwaves and convert them to power need to be cheap; dielectric resonator antennae can be expensive and still be useful for communications, but power transmission is a whole other question.
gkam
1 / 5 (3) Apr 20, 2015
Da Snot, do you expect me to give you a five for character assassination? You even failed at that, because I can prove who I am, but you sound more and more like otto.

"Sock puppets"?

Does he have his hand up your ass?
Da Schneib
1 / 5 (1) Apr 20, 2015
All you gotta do is stop lying.

Is it really that hard, Gracie?

Keep in mind that the nastier you are, the surer you prove I'm right.
Da Schneib
1 / 5 (1) Apr 21, 2015
It's always amusing to see a 16-year-old girl trying to pretend to be a 50-year-old man. There are so, so many things you don't know that make you so, so obvious.
TechMutualist
not rated yet May 20, 2015
It's quite surprising to see a legitimate discussion on an interesting topic brought down with this back and forth crap.

I tend to believe that distributed generation is the most likely path forward for mass electricity production, but if the cost can't come down or utilities lobby effectively to keep the grid intact, then this becomes more feasible. I mean, who originally thought that we would have a criss-cross network of copper covering most of the globe?

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