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Can one obtain a sufficient amount of energy for a household's needs by indirect means (induction or otherwise) from nearby high-voltage power lines? Are there any documented cases of such attempts (successful or not) and are there any negative effects should this be possible?

I'm not asking to validate a specific claim of someone that says they've done it, I"m asking because there are many places online where people are interested in this (http://hacknmod.com/hack/field-of-fluorescent-tubes-powered-by-ambient-current/, http://forum.drumulinvingatorilor.ro/index.php?topic=1154.15, http://www.elforum.ro/viewtopic.php?f=13&t=12814 (content in Romanian)) and I'd like to know if there is any truth to it.

As for people asking for actual claims of success in this field:

http://www.ndep.us/Power-Harvesting-Induction-Magic

Sklivvz
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luvieere
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  • Hi can you provide some existing examples of someone making this claim? Thanks. – Sklivvz May 22 '11 at 16:56
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    If you can have the induction circuit close enough, yes. Negative effects? Getting fried when you try to get the induction circuit close enough. – Lennart Regebro May 22 '11 at 17:23
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    Other negative effects: getting sued when the power company discovers you're leeching power. – David Thornley May 22 '11 at 18:18
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    There seem to be somewhat relevant questions on electronics.SE: http://electronics.stackexchange.com/questions/4664/stealing-energy-from-radio-towers-or-power-lines (possibly even http://electronics.stackexchange.com/questions/8337/can-you-harvest-electrical-energy-from-the-air ) – Piskvor left the building May 22 '11 at 19:29
  • I have heard people question the possibility but no one that I've read actually claims to have done it. One person built a contraption right under a high voltage line and showed a significant voltage that way. However, I doubt they were getting much current. They did get regularly shocked by a metal door on a nearby building once the lines were put up though. Thats the closest claim I know of, sorry I don't remember where I read it. – logicbird May 22 '11 at 22:46
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    This has a direct entry to the Darwin awards guaranteed – Hairy May 23 '11 at 08:14
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    The Mythbusters examined this one within the "Free Energy" myth, under the category "Free for me!". – Andrew Grimm May 23 '11 at 12:27
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    I've heard a myth that a guy once actually did lay a km or two of cable under the power lines, and lived well for a while, but was later caught. However it's only a myth, handed down by word of mouth. – Vilx- May 23 '11 at 13:11
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    @Vilx: I can't imagine how he could have been noticed - power loss would be so tiny. – sharptooth May 23 '11 at 14:04
  • A cable on the ground (or disturbance of the ground if it was buried) might be noticed when they send someone out for maintenance, though. – Random832 May 23 '11 at 19:12
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    @Random832: Maybe, but it's kind of dumb to not conceal the disturbance. I asked a question on Electronics SE http://electronics.stackexchange.com/q/14619/3552 – sharptooth May 24 '11 at 05:17
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    Meta: why don't users dare to post legitimate answers as answers instead of comments anymore? – Anno2001 Nov 03 '12 at 19:46
  • I'm confused, did you want to ask if it is possible? Or if it had been done? Because I see both questions here and I don't think that is reasonable, since such a thing is definitely possible but not practical. – travisbartley Sep 20 '13 at 02:32
  • @Anno2001: Some SE sites are nastier than others. You cannot get a negative vote in a comment. – Henry Oct 04 '13 at 13:31
  • I think this question might be better suited to Physics SE because it's definitely in principle possible, but in practice extremely impractical. – GordonM Jun 18 '15 at 09:16
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    Maybe the guys who want to get free power this way should trade places with the ones who claim to have adverse health effects caused by living near high-tension lines. – GEdgar Jun 18 '15 at 12:34

1 Answers1

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It is certainly possible to "harvest" power via induction from high voltage power lines. There is a vertical voltage drop from the wires to the ground. This effect can power stuff.

For an example of this, see this (awesome) picture of a neon being lit by proximity to the power lines.

neon lit by capacitance source

Also, this energy leakage is openly admitted by power lines companies, for example:

Electric fields emanate from any conductor or wire that carries voltage. Higher line voltages produce higher electric field strengths. The closer the conductor is to the ground, the higher the field strength beneath it tends to be, and the increased possibility of shocks.
Larger objects such as a building or a large vehicle have the capability of a larger charge and therefore the shock could be more noticeable. Backyard metallic objects such as swings, portable grills and lawnmowers have been known to deliver similar shocks. Ungrounded metal wire fences can also receive sufficient charges to cause nuisance shocks.

—source

Lighting a neon bulb is one thing, but how much power can be generated? This was studied multiple times, for example in 1976 by the US Department of Agriculture. One of the major risks (or opportunities to "generate" power) is when building fences parallel to high-voltage power lines.

For typical fence values, h = 4 feet (1.22 meters), GMR = 0.125 inches (3.2 × 10-3 meters) and a ground voltage gradient of 4 kV/M (maximum gradient for a lateral distance of 38 feet from the center line of the 345 kV transmission line, Figure 111-1, and a phase conductor vertical clearance of 29 feet, reference 12) then from Equation 111-3 the magnitude of electric shock current is:

|Ishock| = 15.4 × 10-6 amperes/meter or 25 milliamperes/mile

—source

This is a theoretical calculation so take it with a grain of salt. These are relatively small currents, and correspond to a 15 milliWatts (≈1.5 × 10-5A × 10 ×3V) for every meter of ungrounded fence. Now, a house consumes about 100,000 times more power (kiloWatts).

Is it possible? Yes, there is clearly a voltage gradient at which point how much energy can be harvested is a matter of size of the antenna we use.

Is it feasible? No, because the size is likely to be a few kilometers of ungrounded wire, which is not exactly a cheap solution. It is in fact, potentially deadly, as anyone touching it would get a major shock, certainly illegal and very hard to hide.

I will post more papers if I find them - most are IEEE papers behind a paywall :-(

Sklivvz
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    A fence running nearby an overhead power line is definitively not an optimal "collector" for wireless energy and using this calculation as a argument against the feasibility of energy harvesting is wrong. – Tor-Einar Jarnbjo Nov 19 '14 at 16:09