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.
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.
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
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.
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.
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.
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