German Student Creates Device That Harvests Energy From Air
Dennis Siegel has created an energy harvester that can be used to harvest ambient energy from electromagnetic fields in the air, such as those present near power lines, plugged-in electric appliances, or mobile phones. Siegel is studying digital design at the University of Bremen. (Source: Dennis Siegel)
Back in electromagnetic theory class we discussed the idea of building a car that could operate near power lines to do the same thing this kid is doing. There are power lines running alongside most roads anyway. The antenna would probably be unpractically large, and would have to be unpractically close to the wires to get enough power, but it's probably sorta doable. Either way, it's stealing because the energy coupled into the device only comes from the power company.
Well, I suppose you could look at it that way, dka, kind of like copying someone's CD MP3 collection. But I think that it's more using energy that already exists rather than stealing. And I'm pretty sure it's using the electricity that the wires themselves are emitting...I suppose they come from the power company originally, but at that point a case could be made that it is coming from the wires and perhaps even have its own existence, as it is now a part of the air. But I do see what you're saying!
I agree with Elizabeth: stealing implies that the thief takes away something so there's less of it. That's not at all the case here: this is harvesting secondary energy from a source which is primarily providing the primary energy. It's not like someone's house on the power line has less electricity available, or even that the power station at the source of the line has less energy available. This is using "waste" energy that's been previously unused. There's a lot of "waste" energy in the world created by various sources.
There is precedent for it to be considered stealing in the US. One of my electronics professors related the story of a man who's house was next to a substation. Being a clever fellow he used his old steel laundry pole as the core of a transformer and took himself off the grid. The power company found out about it and sued the guy. His defense was that the power company's magnetic field was infringing on his property and he had a right to use it. The power company said that his use of their magnetic field caused additional drain on their power grid that wouldn't occur if he wasn't swiping their power. He lost. Laws and their interpretations are different in Europe, and the suit might come out differently there. They are much fussier about control of emissions. Another option would be to tune the device to ignore 60 cycle (or 50 cycle in Europe) signals, so you're not ripping off the power company. Tuning for galactic, AM or FM signals is probably not stealing. I have a 50 year old transister projects book that makes a light blink using radio waves.
Anne, You are absolutely correct i too dont agree with the idea of stealing energy because this is not stealing energy we are just utilizing the wasted or excess energy as we know all these electromegnatic devices continue to emit energy even when not working .Harvesting energy from air is an excellent idea we can use these devices at airports where radar and communication devices emit energy to harvest and power wireless sensors that could detect nuclear material .
Debera, I think I may have missed your comment earlier, as I just replied to another user that I agree with you all who are commenting that this isn't really "stealing." I think it's a creative reuse of what's already out there and I think that this type of technology should be promoted.
TANSTAAFL - Thair Ain't No Such Thing As A Free Lunch. A single wire transporting electrical energy which emits an electric field represents a certain parasitic load. When you run another single wire or device that couples the electric field of the first wire, you increase the load. Not unlike a transformer, thus as secondary current increases, primary current does as well. Wires that are designed to emit radiation (antenna's) emit the electrical energy as RF radiation and it can be harvested without diminishing the source, however the available current is miniscule. Charging a small battery in a day from radiated sources is pretty inefficient considering the wide range of other available energy sources.
@Charles- I think if we could use this to generate electricity for 10 houses it's a great achievement. This is like free electricity; we are not wasting our fuel or any other energy to generate this. We are just making use of the energy we waste.
I agree with Bob. There are a lot of proximity chargers on the market. Some are designed for charging electronic devices that lay on top of the charging pad. Another might be that electric toothbrush that recharges when it is put back into it's stand. Essentially, all of these are transformers; two wires coupled by the electromagnetic field between them. If it is non-metered power that is being collected, then it is stealing. If it is from a metered source, then it could be stealing if someone else pays the bill. If it is from a source that you pay for, then it is not stealing, but may be FAR less efficient than a direct plug in charger. As has been stated, there is no free lunch. I strongly disagree with the statements that suggest the power to a neighboring home is diminished or that the source is diminished. Every user in the system puts a load on the source, no matter how miniscule. Were it not so, then a single power plant could supply the whole world with free energy. The only free sources of energy are from the broadcasters, and nature
It's really interesting to read all of this information in the comments about where the electricity is originating and whether this is stealing or not. I would not have thought about it this way so I appreciate all this new perspective. Thanks to our incredibly intelligent and savvy readers for their commentary and debate.
Elizabeth M, I agree very interesting comments and perspectives on this topic of harvesting energy and theft. I'm not quite sure if capturing "free" electromagnetic waves in the air is theft especially if the use is to charge up a battery for personal use. If that's the case, society as a whole has committed a criminal act by using standard FM/AM radios in automobiles. The RF signals are in the ether and antennas embedded within the car radio traps these signals, extracts the audio content, and society reaps the benefit of musical entertainment, educational enlightenment, and public awareness via music and talk radio shows.
If you disrupt the broadcast RF or decrease the coverage area (e.g. by using a very large antenna or array), they might have a case against you. But it would be much harder for the provider to detect the loss, if you are a distance from the transmitter.
However, it is impractical to use RF energy transmitted at a distance. Transmitted EM waves follow the Inverse Square Law (http://en.wikipedia.org/wiki/Inverse-square_law) which states that the power density of an electromagnetic wave is proportional to the inverse of the square of the distance from a point source.
The power is reduced in proportion to the square of the distance to the source. i.e. - If you double the distance to a source, you will only have 1/4 of the power (you lose 3/4 of the power).
@Bob- if we could harvest energy no matter how small it is, it's worth considering as very soon we will be short of power so saving it should be our primary objective. If we could harvest the energy / power wasted I think that's what is required.
I completely agree with you. It is not stealing. If the power company wants, they can design large collectors and place them near power lines to collect the power themselves. The issue is abit different. The field is in public domain. Lets say my house near the power lines. Is their field enterms my property illegaly? It is like my neighbours large tree having branches on my property. I have the righ to rim them as I want. I he produces magnetic field, I can harvest it.
Well go ahead and try that out. I believe that the power company can prove that your 'inductive' connection is making them ~deliver~ power to you, and you are in fact their customer. You owe them money for the power they have delivered... if you don't pay for a service rendered its called "stealing" (last time I checked). If you are not taking anything (i.e. you have not installed any means to do so) you owe them nothing.
If you want to play with semantics... why don't you get a court to agree that you have a right to the electromagntic space around your property... and argue that the power company is delivering a magnetic field that you ~don't~ want and insist they they either shield you from their (by)product... or pay you for allowing it on your property. Otherwise... they are the primary (source) of an air-core transformer and youi are the secondary (load).
There are many cases where power companies tried o distance themselves from any ownership of he magneic byproduct not to be sued for medical problems of residents next to power lines. I have this feeling that ConEdison will not go after me is I park my car on the street and while having luch, my phone will charge.
On the other hand so much power is being wasted, and this is one little way that some can be used again and again.
I think sensor pro has some interesting points. Power companies have certainly distanced themselves from EM radiation coming from their equipment and spent a ton of money "proving" it doesn't cause or even influence medical problems of those living near high-power lines--that's what the business of the entirely non-objective Electric Power Research Institute is all about. OTOH, why the heck aren't they harvesting "waste" energy themselves? Many posts have addressed the science of this issue, and even some of the ethics, but few have said anything about social or economic implications.
Ann, power companies do want to keep their radiated power losses down. It is, after all, a loss that they must pay for. It's like having a leak in a water main. But the cost of capturing that radiated power is greater than the value of the power recovered, so the power companies live with the compromises they made when selecting 60Hz as the frequency in the first place.
Social or economic implications? Well, if a million people took 1 milliwatt/second for an hour each each from the power grid's EM fields, that would be 360 kilowatt hours. My power company charges $0.089 per KWH, so that's $32 per hour or about $280,000 per year if there's a million taps going on 24/7. Or about $0.28 a year per person. It might be feasible to absorb that cost into everyone's electric bill. But the more energy folks take from the EM fields, the higher that cost will rise. It'll be like taxes - many folks paying for this "free" benefit, but not necessarily the ones actually receiving that benefit. Seems unfair and open to abuse.
I believe it is a mistake to say that the power you can draw from the grid's EM fields would otherwise be "wasted." The amount of EM energy that radiates out from the power lines is set by the impedance of the space they couple into. If you set up an antenna, you alter that impedance and so more energy flows into that space than would have otherwise. Hence, you've taken power from the source. You're not gathering power that would otherwise have been wasted in the surrounding space. That power is still being wasted in the surrounding space. The antenna has simply added a new load onto the source.
One small phone charger would not have a noticable impact on the grid, but if millions of people in a city were to try to capture energy that way, it certainly would.
So what your saying is it is a enegry "suck". I have a friend that lives next to some power lines. What if he gets a battery charger from this guy and his batteries are always charged. You think there is a law against this? What about charging from RF? How is that stealing? Then when you get into RFID, oh my god, the lawyers are going to love that one!
Richard, I am not a legal authority nor can I speak for the power companies, but I believe the answer is "yes" there is a law against this. It's considered theft of service, same as if you tapped into a water main that crossed your property without paying for the water. It's only the small size of the theft that makes it something power companies will probably ignore. If you were to take a noticable amount, then they probably would (and have in the past) prosecute.
If by charging from RF you mean taking the radiated energy that radio and television broadcast stations put out, it strikes me that is a different situation. They are not selling the energy, they are selling the marketing opportunity of connecting sponsors with listeners. If what you do interferes with their ability to provide a signal to anyone who wants it, then they too may have legal recourse to stop you. However, to have that kind of effect you would have to take a lot of their RF energy over a wide area. Not very likely. So, capturing and repurposing the RF energy that crosses your path is probably not theft since it is not the energy they are selling.
As to RFID, why do you think that might open a can of legal worms? It is very short range, very short duration, and is intended to have its power captured (by the RFID tag). Again, capturing that energy for your own purpose does not impede the RF creator's purpose unless you interfere with its intended operaton, which you are unlikely to do, or take so much power that the RF creator sees a cost impact.
no, I think my analogy is correct. If you set up something to gather energy from the EM field surrounding the power line, you have created an energy leak that is above and beyond the stuff already leaking away.
To expand the water line analogy, if you put a suction cup on the leak site and used a pump to pull water thru the leak site, thus increasing the net loss thru the leak, you have tapped in even though you didn't create the breach in the pipe.
Setting an antenna out and extracting useful work from the em field around a power line is going to increase the radiated loss from the line. So, you have tapped into the power line, albeit wirelessly, and are extracting energy from it. You are not gathering energy that would have otherwise have been lost, you are adding to the energy loss. The stuff that was being lost is still being lost.
There are all good considerations. I think other users address all of these comments, but I guess it remains to be seen how this will all be handled if this device is used and commercialized more broadly. Thanks for your comment, RichardBradleySmith.
@HarryB, you may have hit on the pertinent point in a wider discussion of rights. If someone hits your car at high speed with their own, they are "delivering" free energy to you. Should they be able to charge you for that? I think the ability to control the distribution of an energy or information source is critical to whether it might be considered "stolen" or "harvested" (or "imposed" for that matter). For a power company to attempt to claim ownership of the waste EM energy from power lines would subject them to even more lawsuits from parents who charge that living near a substation caused leukemia in their kids. I seriously doubt the companies would claim the energy back. They can't control the energy release. If your car leaked fuel on the street, and someone came along with a rag and sopped up the fuel with it, could you sue the person to recover the cost of your fuel?
I don't actually know the answer to that, but I tend to doubt that the matter is so clear-cut as to be able to call the energy "stolen".
On the other hand, a year ago I watched a Youtube video (since removed) with a schematic for a device that charges a small battery from radio waves. The idea was to charge a cell phone in an emergency- in a few hours the guy could turn on his phone (for a brief period). As others have said, nothing shockingly new here.
Great idea for a new product, Chuck_IAG. If you were to design something to 'harvest' the free, unintended energy in a car crash (instead of delivering it to the occupants) you'd be a wealthy, wealthy man. I agree the power companies do not want to own the 'free space' energy arounf their power lines, for exactly the reasons you note. However... adding an apparatus to harvest power (for yourself) is exactly the same as if you climbed the pole and tied a wire to theirs. As others have elegently said... making an antenna draws MORE power than the free space would have... measureably more power... and that can be interpreted (as the courts have done) as theft. They lost (power), you gained it. If you made a device to drain a portion of the fuel from cars as they passed (that they were not otherwise leaking...) that too would be theft. They lost (fuel) you gained it. The free 'harvested' energy isn't yours to take, because it wasn't free in the first place.
Richard, the induction charging systems I know about plug into a wall outlet to draw their power. That outlet is part of a metered power system. Hence, that power is being paid for and all you are doing is changing the way in which it is delivered to the target device. Power companies probably love them, since the delivery method is not as efficient as a direct wire connection (you're radiating in all directions) and so takes more power and provides them with greater revenue than if you simply plugged your unit into a power brick of some kind.
Not only that, but it's charging with much greater inefficiencies than something plugged in directly. At the end of the day there is no free lunch, everyhting is tied together with varying degrees of loss. If it weren't so we would have had perpetual motion machines years ago. I would go as far as saying that there should be a massive tax on these significantly lossier chargiing systems, to help pay for the additional environmental damage they do. In the late 60's in Germany it was popular to have TV's designed do that the picture tube filament was permanently powered so that we would have instant on. That was around 6W plus losses for every TV in the country. Then they decided it was a bad idea environmetally. Now some other twit comes up with the idea of designing a lossy charging system for a multitude of battery devices. How before the ~1W of additional loss times ten times as many devices is concidered unacceptable? Here's me thinking engineers thought ahead??
Hi, shehan, the idea is that there is ambient electricity coming from those wires that can be harvested. Think about when the electricity goes out and how quite everything is...there is no longer the hum of electronic devices or appliances. That hum is actually power being emitted from those electronics, which this device has been designed to exploit. Make sense?
@Elizabeth - Thanks, I think collecting / harvesting this energy is not a crime. If not harvesting is a chime and a waste. At least the electricity companies need to set up stations to harvest this energy.
There is still a basic misunderstanding of how transformers work. If we consider a perfect transformer with no load on it, there is only the initial surge as the first magnetic field builds up. Then the voltage is transferred to the secondary almost simultaneously. When the field collapses, the current used is put back into the system. This goes on at 50 or 60 Hz and no energy is consumed. The power company could do this all day and only have to pay for the generator's friction losses. It would see no drain on their system- no LOAD, we say. They would make no money, and they would lose no money, other than the friction losses, payment on the building, maintenance of the equipment, payroll, taxes, fuel, and payoffs to government officials.
But if Mr. Farmer comes along and runs a wire (a secondary, not primary), then when current flows through the voltage buildup in his home-made, extremely inefficient secondary copper skeleton key, the generator would know it, as the collapsing field no longer gives him his current back. There is a loss. There is a consuming of the power. But all his other bills go on with an increase in fuel costs and maintenance costs.
There, I hope that clears things up a bit. Power generation is only as expensive as the load on the system, minus the losses and bribes.
Now I like this idea, shehan. If they don't like the idea of other people doing it, they should set up harvesters themselves...that way no precious energy is lost. We could perhaps solve the energy crisis this way. What a good idea.
You're welcome, notarboca. I'm quite frankly surprised by the level of comment I've received on this one. You never know as a writer what is going to provoke a response, and there are opinions and angles to this story that people have posed that I have never thought of. Thanks for reading.
Actually, people have been prosecuted for stealing energy frmo the power company on lines that ran through their own property. You can't even take water out of the ground on your own property without Dear Leader's permission. You can't keep airplanes from flying over your own property and sky. Deer that feed on your garden can't be shot out of season. So, just because a power line is on your land doesn't mean you have ownership over it.
So, charging the battery in the article is not right. It isn't even clever or unique.
Thanks for your opinion, warren. I think there are some that may feel differently about this, perhaps even believe that electricity should be a free resource. But I will let them weigh in on that! Appreciate your reading the article.
Yes, I had a friend that owned a farm about 50 years ago with high-tension lines running on his lot line. He ran a wire looping several times around his acreage on his fence, simulating a very large transformer coil, and ran the two ends through a transformer and rectifier that charged a bank of batteries that ultimately powered his farmhouse. His coil put an extra load on the transmission system which was detectable as a load on the power grid. The power company somehow tracked him down, resulting in heavy fines and prosecution for theft. As mention in other replies, you don't have legal ownership or rights to everything in your "space".
@jhankwitz – The problem is the load on the primary lines, I think this heats up the transformers and add additional lo9ad to it. That's why power companies look for such people. Isn't there any way to do the same without creating an additional load on the primary line?
You can't get something from nothing. If you consume power, it has to come from somewhere. Putting a load on the secondary of a transformer will cause a load on the primary. The farmer in my discussion was wirelessly stealing power from the grid. His setup was very costly and inefficient, but he was able to get something out of it.
The farmer's setup was expensive because of the cost of the miles of highly insulated copper wire he had to run multiple times around the perimeter of his lot. It operated as the primary winding of a transformer and worked because one side of his lot was close to the high voltage wires and the rest was further away. It was extremely inefficient because this transformer's core was made of air.
You can't get something from nothing. If you consume power, it has to come from somewhere. Putting a load on the secondary of a transformer will cause a load on the primary. The farmer in my discussion was wirelessly stealing power from the grid. His setup was very costly and inefficient, but he was able to get something out of it.
@Warren- true there a many who were prosecuted for stealing power from line that went through their property. Do you think this is a crime, as this is electricity that is wasted? I think government need to encourage such acts to minimize the electricity we waste.
Actually, it isn't really wasted. The magnetic field around the Power company wires will continue to expand and contract, and as long as there is no contact with a load the field will be preserved (largely). But when the lines of flux created by the 60 Hz AC current in the wires cut through a conductor with a load (the theft device) then energy is transfered just like in a very poor transformer. Otherwise, the energy stays within the confines of the electric grid.
What amazes me is that they were able to detect the farmer's theft. How in the world, with millions of kilowatts being consumed did they notice a little bit missing?
@warren; Helicopters and aircraft overfly power lines fairly frequently, they can measure the strength of the electric field and notice 'dips' where the field is interracting with something. Also sending/receiving FM signals over the power lines allow power companies to locate loss. Power companies lose a siginificant amount of power through parasitic inductive loss. The national grid loss is dramatic. I've read that some power lines have changed to DC to reduce this loss.
Very clever, Mainly Bob. I didn't think about sending other signals over the line to find losses.
They switched to DC for a number of reasons, not the least of which are skin-effect losses. I understand they run to 1,000,000 volts on these lines. That would make it harder to steal by transformer effect.
However, if you were really stupid, had a really long pole, a bunch of voltage-drop high-voltage resistors, and I repeat really stupid, you could possibly drop the voltage enough to light a small lamp for free.
One million volts DC! Imagine! So with a dry-air dielectric breakdown of 35KV per inch, a million volts would require a minimum of 28" for dry air, quadruple that at least for moist air (once an ionized trail starts, avalanche breakdown will soon follow. I think I'd rather buy a battery charger. People trying to steal by making any kind of contact with a million volt DC power line would immediately qualify for a Darwin award.
Maine-Bob, the graveyards are full of people whose gravestones should have read, "Nope. That didn't work!"
I was driving on I-8 in San Diego one evening and saw a man on the high voltage platform next to the freeway. Then I saw a flash of fire and he was burning! He was drunk and decided to climb the tower. He survived. "Here's yur sign..."
@warren – I wonder how the farmer got caught, as you said we are talking of millions of kilowatts. I think it was the word of mouth or someone might have seen wires connected to the towers from his house.
Power is monitored at substations or below, so there are not millions of killowatts being sensed. If he was stealing enough to power his entire house, they would detect the loss.
The first electric Co-ops were formed in rural areas like Oklahoma when neighbors would pay to run power lines between themselves and a nearby distribution line. The electric companies didn't want to power scattered rural homes because they would never get a return on the line investment. Even when the small communities ran their own lines, the power companies didn't want to hook them up and become liable for their distribution.
To force the issue, the co-ops would put poles next to the electric company's line for a distance and parasitically power their homes.
The EM field of conductors is NOT wasted energy and any EE should know that. It is simply the result of passing current through the conductor. Sheilding is not an option when considering the massive currents involved in power distribution.
You can use these devices all you want behind YOUR power meter where you get charged for the energy you consume. But using power you are not being charged for, plus causing additional distribution loses to the provider (find your own EE to explain); is increasing the provider's costs and decreasing the available energy to legitimate customers. IT IS THEFT! period!
I agree - it is stealing. Where a radio/TV station brodcasts energy that will propagate away never to return, most of the line frequency field around the line is energy that returns to the line and does not propagate away (the wave length of 60Hz is almost 5,000,000 meters). Putting an energy harvesting device near the line is just making an illegal transformer.
@dka – I was just wondering how the power could be used for the car without touching the power lines. I was under the impression that power travels through wires and not over air. It's nice to see a student working on such a project.
Harvesting energy is in effect creating a parasitic load on an electrical field
(be it RF, low frequency, etc). A normal radio receiver is a load on the transmiiter, its just too small to be significant. If you designed a really large receiver designed to trap energy, you'd make a measurable dent in the radiation pattern. The radio transmitter would not broadcast as far past your direction. If your load is small enough not to be noticed... it might appear to be ~free~ power.
A windmill generates 'free' power because no one paid to make the wind blow... and no one was otherwise harvesting the wind. If you built enough windmills you would indeed (eventually) run out of wind. Only when the load is insignificantly small does it make sense to consdier it 'free'.
A better idea is to harvest energy that is otherwise thrown away, or that people are paying to get rid of. Using (for example) waste heat from a cooling tower to heat homes is an example.
At least with the radio transmitter, the piper is paid - so to speak - by the owner of the transmitter. Energy is consumed in the final amplifier of the RF transmitter and the radiated energy is supposed to be lost. You could in theory capture the entire radiated envelope and not change the amount of power consumed. It is not unlike the other end of the EM spectrum, sunlight. No matter how much you capture, the radiation from the source does not change. On a current carrying conductor like a power transmission line, the electricity is supposed to be delivered to an end user, not consumed en-route. Stealing is stealing, no matter how scientifically you describe the process.
The owner of a broadcast radio transmitter would certainly consider it stealing if you captured his entire RF output, and did not purchase a commesurate amount of product from his sponsors as he would have received if you had ~not~ effectively blocked his transmission. The product there is information, the RF filed is the carrier... still stealing.
I have to agree with Warren on this one. There isn't much of anything novel about this. It certainly isn't harvesting energy from air!! It's just using an electromagnetic field to drive current in a secondary coil. Another name for it would be a transformer. I also agree that it's technically stealing. If you created a big enough coil to encompass the powerline, or any wire carrying current, and then use the induced current to power a load you will create a load on the primary line. It's just a very small transformer creating a negliable load. This basically no different than plugging in your cell phone at work. Are you using power for or from someone else? YES. Will you get fined or fired for it? Probably not. Change the quantity and scale, however, and the free ride will end.
Back in 1970 at CSULB my professor told us about the local SoCal Edison invading his backyard to put a large ground mounted step-down transformer. Took up quite a bit of area and the professor was not happy. He found out that good old SCE had the land rights to do this. So it went ahead and did it. The professor asked them if he could build a wooden box to hide the transformer and they allowed it as long as there was no top so heat could escape. He got it in writing and built the 'box'. He then asked his electronics class for volunteers to come to his house and do a bit of work. He had them wind many feet of wire around the box and connect it to party lights hanging in the backyard. Voila! Free backyard lights! Yes, SCE was unhappy. Not sure how it turned out but the professor was smiling. Made for a good story no matter what.
I remember a crystal radio (schematic) that used two receivers. One was to be tuned to a strong local station... this output was rectified and used as a DC supply to a single transistor amplifier in a second receiver, which you were free to tune to another (presumably distant) station. Voila. Free power.
The real 'free power' is to harvest wasted energy... for example a stack of piezo elements could presumably be used to harvest the energy from bumps in the road as you drive your car over them... rather than wasting that energy as heat in your shock absorbers you put it in your battery. That is a win-win situation... although I doubt you would choose the bumpiest roads (or pay an exhorbitant initial cost) just to get that 'free power'
as to wether or not this is theft, consider this: is it stealing if you build a device to receive, decode, and view the satellite signals that are continuously being beamed to your property? would DirecTV or Dish Network come after you? in that light, should the power company do the same?
ungarata, if you simply take the RF power reaching your property, then the satellite providers won't come after you. But ify ou decode their signals, they consider that theft of service and they will come after you. There have even been cases of groups that meet to discuss and share the technology of decoding being treated as criminal conspiracy organizations as the purpose for such discussions is assumed to be collaborating to steal service.
If you make a noticable dent in the power grid by harvesting from their EM fields, the power companies may well prosecute. If, however, you take that radiated energy from the power lines inside your house, you've been metered for it and so you have already paid.
It's theft pure and simple, both morally and legally, if you really understand the underlying theory as presented by HarryB, bob from maine, and others. And yes, it is also illegal to 'decode' the encrypted signal from DirecTV or Dish TV although 'viewing' the decoded signal will probably be the secondary infraction. But all this legal stuff takes away from primary presentation of the article.
I think it's great that a new student has discovered this phenomenon for himself, either independently or as an extension of his studies. At some point in time all EE's had this same idea until we were nudged by the more 'experienced ones' (professors, teachers, etc) to review the theory and conclude for ourselves if the EM field produced is 'waste' energy or if the parasitic device is really just another load, drawing more energy from the source than was supplied or intended. As for range, the electromagnetic field is a fundamental force that will always encroach on someone's property since it has infinite range.
Guess what. You can hold up your cell phone and measure the amoount of energy being eaten by your phone at a specific frequency. Every antenna is designed to pull energy out of thin air at specific frequencies and provide it for amplification by a receiver. The amount of actual power you can pull out of the air is proportional to the amount of hardware and software you've installed to do it. Pulling enough power from the grid to power a toaster or other appliance may not be very be cost effective.
"You can hold up your cell phone and measure the amoount of energy being eaten by your phone at a specific frequency. Every antenna is designed to pull energy out of thin air at specific frequencies and provide it for amplification by a receiver. The amount of actual power you can pull out of the air is proportional to the amount of hardware and software you've installed to do it. "
@jhankwitz- Yes all antennas have the capability of pulling power, as you said all depend on the hardware and the software you use. But this hardware need to power up to pull the power from the grid. The more power you give your hardware the more pulling power it has. I think this is not a cost efficient way as you said.
Most of the arguments in the posts have been argued before. As noted there is no free lunch. As much as I would like to disagree the only "free" energy is that which no one paid to generate initially (e.g. sunlight). Someone has even already argued that there will be a price paid for the waste heat generated as a result of capturing the additional sunlight. The one idea I have not seen commented on is that of Tesla. He wished to build a tower that could be used to transmit energy which could be harvested at a distant location. It was started and never completed. There are those today that hope to resurrect the project. I doubt that this would provide free power, but it might make delivering the power to a remote location easier if it could ever be achieved.
I think that I have read that there have been successful prosecutions of those who did build systems to capture energy from some of those larger , longer, overhead transmission lines. I researched that after seeing that there was about a half mile of such line along the boarder of my uncle's farm. At that time a half mile of wire strung along the tops of fenceposts similar to an electric fence would be able to recover a useful amount of power. But the ruling that I saw claimed that since the power clearly came from the overhead line, that the act was indeed theft of services.
Tapping power from the ambient electrostatic field inside a structure is different for many reasons, starting with that area being "downstream" from the metering. But the voltage induced from the proximity to electrical wiring has a very high source impedance, with the result that not much power can be recovered. IT would be very educational to see waht the device produced by the student actually consists of. My bet is that a battery of some sort would be found, since in the area of the device in the photo there is not enough power available to even light the LED that we see. "If something sounds unbelievable, it probably is". I didn't say it first, but it is still true.
"Stealing" is not the same as harvesting. There was no intent of malice here, but rather to indicate a potential mechanism for energy recycling, from whatever source may be available. There are currently (no pun intended) myriad devices and techniques for "energy scavenging" technology already being used or in development. Why should this be considered any differently?
Thank you for your comment, charles000. I, too, thought a lot of the concern about stealing the energy was unwarranted. As you say, many of these devices are just showing the potential for taking advantagae of the energy that's out there and available, so it's not really so different.