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I found a website recently about harvesting energy from the air, and I am wondering if someone could tell me why the following wouldn't work?

Their "generator" is supposed to make electricity from the ionosphere (not UV, X-Ray, etc). Some claim it can knock out your electric bill totally (a bigger version, not this example). From what I understand, this is possible (it was discovered by Nikola Tesla), however this diagram doesn't look like it would work. Any help would be appreciated.

An example from the website:

You need:

  • (4) 1N34 germanium diodes
  • (2) 100 µF 50 V electrolytic capacitors
  • 0.2 µF 50 V ceramic capacitors

Here is the electrical diagram they provide:

Diagram of generator

And they claimed to power a cell phone with it. I am not sure what kind of antenna to use.

While this seems like a sham, I just found this website recently and am looking for more info on the physics behind it.

Perhaps Teslo's patent explains things better, so here it is: Patent 685958.pdf

Found something: Here is a page that explains it. Nikola Tesla free energy: unraveling Greatest Secret

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"PDF for sale" should tell you all you need to know about this - its a scam. "Threats from energy companies" is also a classic telltale sign of prople who are either fraudsters or self-delusional. – mikeselectricstuff Dec 27 '10 at 16:40
Virtually identical post as here: electronics.stackexchange.com/questions/4639/… This question may still be useful as a method to refute the bogus claims on the linked website, however. – Nick T Dec 27 '10 at 16:42
@Arlen: In most countries around the world, all works are copyrighted by the author by default unless mentioned otherwise. In the US, the relevant law would be the Berne Convention Implementation Act of 1988, I believe. – Nick T Dec 27 '10 at 17:55
I watched the ad video and I'm appalled. This is the biggest load of crap and lies I've seen since "The Secret". Watch it at your own risk. You could write pages about what's wrong with it, which is more or less everything. It should be an incentive for more scientific education in high school, so that more people realize why it's a load of crap, and won't be gullible enough to buy this kind of rubbish. – stevenvh Dec 27 '10 at 18:31
Any company that's developed a device for generating useful amounts of energy from thin air would not be selling plans for it. They'd keep the design a secret, build a bunch of power plants, and sell the energy. Free energy = free money! – endolith Dec 29 '10 at 20:35

16 Answers 16

up vote 15 down vote accepted

To address the original question of "Is Nikola Tesla's free energy discovery...", Tesla never created a "free energy device". One of his noted ideas, however, was a system to intentionally transmit power wirelessly. Power companies don't intentionally radiate energy (as it's a pure loss for them).

As an aside, Nikola Tesla was one of the first true electrical engineers, taking arcane, hard-to-understand forces and turning them into marketable solutions. While there is no doubt he was brilliant, this revolutionary engineer would quickly tell you that if you wanted to harvest naturally occurring electrical fields (not those he intentionally radiated) it would take an antenna (or an array of them) on a truly grand scale.

Regarding the document you linked:

Chapter 4 - Tesla's Radiant Energy Device

This chapter discusses a patent by Tesla which discusses using either the photoelectric effect via "ultra-violet light [...] and Roentgen rays [X-rays]" to generate a positive charge by ejecting electrons, or cathodic rays to capture electrons and generate a negative charge.

While you might be able to use the photoelectric effect from solar UV on metals, with great care, you are going to derive an extraordinary small current, certainly far less than you would get with a photovoltaic (solar) cell. PV cells use the photoelectric effect, but within a semiconductor.

Chapter 5 - The Tesla Coil

Tesla coils are essentially antennas that can radiate and receive a great deal of power. In order to actually capture an appreciable amount, much, much more must be broadcast on the particular wavelength that the coil is tuned to. Because they are tuned, they cannot capture broadband noise

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Tesla did some really cool stuff, but don't get to the point of hero worship. Some of his ideas about physics were wrong. – endolith Jun 23 '11 at 15:56
@endolith, and he slowly went mad over his life thinking he could get energy from the ether and such. He was however able to think through his designs in his head and was know for the ability to build something and have it work the first time. Pretty cool in my opinion. Of course many people worship da vinci, calling him an engineer. What good is an engineer whom did not share his secrets and help the world? It is our job to improve the quality of living of the populace, not to be able to and hide it. – Kortuk Jun 25 '11 at 9:04
If the coil is large enough, would it absorb energy from the ionosphere? Tesla was into that- he was the first to measure the voltage of ionosphere... I was thinking that the Wardenclyffe Tower was potentially a power generator (the coil was for absorbing "environmental" energy). – Ben Welborn Jul 14 at 16:05

alt text

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Clever answer. :) – nitro2k01 Apr 18 '11 at 21:42
Cooler version: en.wikipedia.org/wiki/Vaneless_ion_wind_generator But I don't know if it would really work. – endolith Jun 23 '11 at 15:56
haha a coal plant in the back – skyler Jun 15 '13 at 1:26
@endolith: I saw pictures of such a generator built on the campus of a Dutch technical university. A few square meters in size, I don't recall how much power it generates. (BTW, the name on WP is ill-chosen; it suggests the apparatus generates wind :)) – radagast Nov 22 '13 at 9:05

SPICE simulation:

Bogus Tesla Generator
Vin 1 0 0 SIN(0 1 34k 1ns 1e10)
C1  1 3 0.2u
C2  1 2 0.2u
C3  4 6 100u
C4  5 4 100u
D1  3 4 Dgermanium
D2  4 2 Dgermanium
D3  6 3 Dgermanium
D4  2 5 Dgermanium
RL  5 6 10k
.model Dgermanium D IS=200p RS=84m N=2.19 TT=144n CJO=4.82p M=0.333 VJ=0.75 EG=0.67 BV=60 IBV=15u
delete all
tran 600u 60
plot V(5,6)

34kHz was chosen for transient analysis almost arbitrarily, but it is the AC analysis that tells the story.

Vin: 1Vpp 34kHz signal, no load:

transient analysis, 1Vpp 34kHz, no load

Vin: 1Vpp 34kHz signal, 10kΩ load:

transient analysis, 1Vpp 34kHz

Let's check the AC response, from 0.1Hz to 1GHz, again with a 10kΩ load:

AC analysis, 1Vpp, 10kΩ load

It's all floating, you say? Well, here's the results with node 4 grounded:

transient analysis, 1Vpp 34kHz, no load, node 4 grounded

transient analysis, 1Vpp 34kHz, node 4 grounded

AC analysis, 1Vpp, node 4 grounded

Although 1Vpp is massive to be floating around, what happens when it is large, such as standing in front of a microwave transmitter? (Other than the blocking caps blowing up.)

Vin 1 0 SIN(0 10k 34k 1ns 1e10)

transient analysis, 10kVpp 34kHz

AC analysis, 10kVpp

And with node 4 grounded:

transient analysis, 10kVpp 34kHz

AC analysis, 10kVpp 34kHz

Nothin'. Guess it doesn't work. Any corrections or suggestions are appreciated. Code is Berkeley Spice3 compatible'ish, but really isn't fit for anything, including merchantability.

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Which spice program are you using on OSX? – akohlsmith Dec 27 '10 at 21:03
@AndrewKohlsmith, MacSpice; netlist- and command line-based. I'm not much of a SPICE guru, but it seems to work well. – tyblu Dec 27 '10 at 21:17
This answer is probably the one of the most helpful ones, along with the one I marked as the answer. – Arlen Beiler Dec 29 '10 at 14:53
@DarenW, About as much sense as any other analysis on a bogus circuit, but what do you mean? Rectifiers and doublers have frequency dependancies when modeled with non-idealities as I did. – tyblu Dec 30 '10 at 7:13
Look at the multiplier on the Y-axis, @davidcary ;) – tyblu Dec 31 '10 at 0:40

The "air" is full of electric fields. When I touch the probe of my scope with my finger I can see a 50Hz sine wave of 6Vpp. The problem is that your antenna (your finger or anything else) doesn't capture any serious amounts of energy from the fields: once you load the detected voltage it drops to almost nothing. The same with the circuit in your question. So, electricity yes, electrical energy no.

The energy stored in a capacitor is equal to 1/2 * C * V^2. This means that for the same amount of energy the voltage over a capacitor decreases as the capacity increases. So, if you want to use a 10uF capacitor instead of a 1nF the voltage will only be 1% of your starting value, and most likely too low to overcome the diode's voltage drop, even for a germanium diode. BTW, germanium is not going to help, as its voltage drop is almost half of a silicium diode. The solution is a tin diode, which has a neglectible voltage drop. You'll have to cool it to tens of degrees belows zero, however...

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I'd probably say useable energy, no. More to the point, what antenna you use will largely determine what frequency you will capture, "bulk capacitive" perhaps being the most efficient for 50-60 Hz line power. – Nick T Dec 27 '10 at 17:06
You are a serious coupler! I only get ~1Vpp ;) – tyblu Dec 27 '10 at 17:07
How much energy would 50 feet of copper tubing capture? – Arlen Beiler Dec 27 '10 at 17:14
@tyblu: you're not touching the ground wire at the same time, are you? 'cause I'm not. – stevenvh Dec 27 '10 at 17:47
@Arlen: I bet you could reach up to a power-co. kV line with 50' of copper, so potentially, lots. You need to specify more details if you're talking wireless. – Nick T Dec 27 '10 at 18:04

To answer the question in your title of "Can you harvest electrical energy from the air?", yes you can.

Can you do it efficiently and actually make it a marketable product? If someone has already done it, wouldn't you think it would be all over the news and be very popular?

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It's a big-corp. conspiracy! – tyblu Dec 27 '10 at 17:19
If it seems too good to be true, it probably is. – stevenvh Dec 27 '10 at 17:25
@mark: ​​​​​​​​win. – Nick T Dec 27 '10 at 18:02
@markrages: sorry mark, I removed your picture because it completely alters Kellenjb's answer. Please post it as a separate answer. – stevenvh Dec 27 '10 at 18:37
@stevenvh, I do not think it completely changes it either. Let @kellenjb decide what he thinks. He very well might go either way. Next time flag @kellenjb and ask him. With a tiny bit more edit this could go from prose to a substantial and thought provoking answer. – Kortuk Jun 25 '11 at 8:51

Is it possible? Yes. But unless you are talking about 'receiving' a man-made source such as a nearby broadcast station or a power line, and even then in conjunction with a huge receiving antenna, it's impractical as a way to obtain more than a tiny amount of power. But a tiny amount can be enough for a crystal radio, or to power a microcircuit which transmits an extremely weak signal.

For most power-generation purposes, you'd get orders of magnitude more return on investment from photovoltaics or a wind turbine.

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It's worth noting that radio receivers which "pulled power out of the air" used to be widely commercially available; their performance was feeble, but getting anything better would generally require using vacuum tubes that gobbled expensive batteries. I would think it might have been possible to improve performance by adding a small battery and capacitor to bias the diode, but I don't know if that was done. I also saw in a museum a radio that used a rotating disk, some ferric beads on a string, and a diaphragm to mechanically amplify sound (the friction of the beads... – supercat May 3 '13 at 15:31
...on the disk would supposedly be affected by perpendicular force induced by the incoming signal; since any friction would be added to the tension of the string on the diaphragm, this could, if the coefficient of friction was greater than one, cause small changes in magnetic force to produce larger changes in force on the diaphragm. I have no idea how well such a technique could work, since it would seem hard to control unwanted resonant behavior, but it seemed an interesting concept. – supercat May 3 '13 at 15:34

Let's suppose the circuit you show works. I don't know if it would, but it seems at least possible that you could harvest small amounts of energy from the electrical noise in the air. How small is small?

The circuit you showed has 4 capacitors-- two 100 uF caps and two that are 500x smaller. Let's ignore the small ones, as they're not used for storage, as David Cary points out in the comments. How much energy can they hold at their peak voltage of 50 V?

The energy capacity of a capacitor is 0.5 * C * V2 joules. We have 2 of them, so the total energy is just C * V2 joules. Substituting in the actual numbers, that's 100 * 10-6 * 50 * 50 = 0.250 joules. We're talking about electricity, so let's convert that to units of kWh, which is how the electric utilities measure energy. 0.250 joules is 7 * 10-8 kWh, i.e. 0.00000007 kWh. In the USA, one kWh costs around $0.10, so this is worth around $0.000000007. If I have my zeros right, that circuit (assuming it works perfectly) can store a maximum of about 7 billionths of a dollar worth of energy.

Of course, by hooking the circuit to a cellphone battery, you'd be limiting the capacitor voltage at 3 V, or whatever the battery voltage is. In this case, the capacitors don't actually serve any purpose as their storage capacity is dwarfed by that of the battery, and they also allow some reverse current leakage as well.

The bad news is that if you remove the capacitors, all you have left is some diodes. It's actually common practice to put diodes in this configuration when driving inductive loads like motors to reduce arcing when the motor stops; they're called "flyback" or "freewheeling" diodes.

Unfortunately, I can say with authority that if you leave a lead acid battery sitting in your garage with just a flyback diode connected, it will not charge itself. With lead acid batteries, they eventually undergo a process known as sulfation, which means that they stop accepting charge. In the long run, you have to load them into your trunk and take them to a household hazardous waste dropoff on a Saturday morning.

I'll stick with the electric bill, thanks.

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The circuit has an input; the antenna (or coil, plate of a cap, whatever). You're interpreting it as a closed system (with some initial conditions). – Nick T Dec 27 '10 at 18:53
Yeah, that's true. The storage capacity is still limited as described. If the caps aren't storage, what are they? – pingswept Dec 27 '10 at 18:58
-1 irrelevant. The capacitors in the PSU in my computer and in a Cockcroft-Walton voltage multiplier are connected with diodes in more or less the same circuit shown by the original poster -- a voltage doubler. Those small capacitors connect the antenna -- the source of the power -- to the rest of the circuit. "Let's ignore the small [capacitors]" is like saying "let's ignore the power cable from my computer to that mysterious socket in the wall". The small capacitors in those 3 circuits aren't used for storage; they are used to pass AC current and block DC current (aka "voltage shifting"). – davidcary Jan 1 '11 at 23:08
I agree with you that the small caps are used to pass AC and block DC, and I've added a note about that to my answer. My assumption, which is seems you disagree with, is that the circuit is intended for energy storage, as it is described as a replacement for a battery. Do you agree or disagree with my main point, which is that the circuit can store very little energy? – pingswept Jan 3 '11 at 3:07
Sure, but in the WiTricity case, they're irradiating the antenna from a short distance at a tuned frequency. The crystal radio example is perfect-- that's a very similar case to what we've been discussing. I think that a crystal radio antenna captures much less than 1 W and thus would be useless for powering a cellphone. – pingswept Feb 25 '11 at 23:05

I've heard of rural inhabitants coming under legal scrutiny for "harvesting energy from the air" by means of massive coils made from, say, chicken-wire (read inductors) situated strategically under certain high-voltage electric transmission lines... anyway remember your ECON101, TNSTAAFL.

Edit Apparently it's more efficient to use long perpendicular wire (see comment)

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How could that possibly be stealing? Isn't it just wasted anyway? – Arlen Beiler Dec 27 '10 at 18:55
What they would be constructing (in this almost assuredly apocryphal tale), is essentially a giant transformer with a half turn on the primary. This would have an effect on the HV line, but the power company actually detecting it (electrically) is unlikely. There might be a grain of truth in the tale where the power company saw something bizarre reaching towards their HV lines during maintenance, making them very nervous, so they tell whoever to stop. – Nick T Dec 27 '10 at 19:24
@Nick Mythbusters confirmed this story apparently; and this strange dude on youtube set them straight on how to "do it right" it seems: youtube.com/watch?v=6hs9Gz4JuhI ... wow, that could have been way more entertaining :) – vicatcu Dec 28 '10 at 0:09
@Arlen Beiler - It is stealing because you are essentially inductively coupling power from the power lines to a real load in which the energy is supplied by the power company but not measured by one of their home meters. As for being wasted anyway, yes, some energy would be wasted by radiation, but when intentionally matched & coupled through a crude transformer as described, much more energy would be delivered than would be if it were simply radiated from the lines unintentionally. – Joel B Sep 8 '11 at 18:28

There were some guys at MIT a few years back that did wireless electricity transmission. They called it "WiTricity". In this case though they were intentionally trying to transmit electricity wirelessly and it only works over very short distances (~7m). If you don't have a very powerful energy source near your receiver it's not going to work.

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@tyblu: Microwave beams and witricity are pretty different. Witricity uses resonant induction, while microwaves are received by "rectennas" and converted into DC. – endolith Jun 23 '11 at 16:01

Another issue I must have with this circuit is that the 1N34 germanium diodes can only conduct about 50mA. I know of no cell phone drawing less than 250mA; most can draw upwards of 1 amp. Those diodes would be toasty, if the circuit ever worked, which it won't.

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put em in paralel – skyler Jun 15 '13 at 1:25

I've been playing with the idea of energy harvesting. I've managed to get a steady half a volt of DC of untested amperage capability. After some consideration I gave up on the idea. It occurred to me that all the EMF we're trying to get is not only generally very small, it's also random. This means that it occurs in varying phases. Two opposite phase EMF's hitting the same antenna will cancel each other. It's improbable that two mirror image EMF's will hit the same antenna, but there is enough phase cancellation going on due to the random and prolific nature of EMF's to keep the harvest potential very, very small.

My $.02

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The Radiant Energy device is actually different from what you describe. The 'antenna' is actually a (very) large isolated metal plate raised to high altitudes (closest you can get to the ionosphere) while isolated from the ground, and tethered through a copper wire all the way down to the ground. Assuming that the ionosphere is charged positively thanks to "cosmic rays", and the ground is negatively charged, a potential difference exists of a few hundred thousand volts. But this energy is static and won't do any work as it is. For that, Tesla proposes connecting the wire to a very large capacitor that charges then discharges into some form of oscillating or switching device that could produce usable work, before sending it down to ground.

It's like a device that can harvest lightning bolts, even when the resistance of the air is not low enough to naturally allow them (such as during a storm).

Is it possible? I don't see any reason why not. Is it free energy? Yes. But then so is oil if you happen to own an oil well. The term 'Free' energy is very misleading. The problem with oil is that it is not renewable. So a better name for Tesla's Radiant Energy Harvester would be an unlimited source of 'renewable energy'.

But then again, Solar, wind, tidal and geothermal are all renewable energy sources and are very well established and reasonably cheap to build and operate. The point is we don't really need "Free Energy sources that the big oil corps are keeping from the rest of us". Those sources are already there and no one is keeping anything from anyone. What we need is more legislation and incentives to invest more into research to optimize and further develop them harvesting (and especially storage techniques).

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I have actually built this circuit. It "harvests" about 1-3 volts using a 200 foot "long wire" antenna.

It can be used to light an LED (with a joule thief), and even power a small motor that is specially built for low voltage/amperage use. Lasersaber has a motor that I use and it works great.

The motor runs 24/7 during the summer, but stops in winter.

It can't power much more than that with the mighty 20MA of current that it provides.

So, Yes, it works. It just does not do very much.

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I'd call 20 MA (20 million amps) very impressive. Do you mean mA (milli-amps)? – transistor Nov 28 '15 at 22:05

The vital thing missing from the circuit is that the 'antenna' has a whirly thing on top that produces 48kW in a good breeze.

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Would that help much? The antenna is only one wire. I know what you mean, though. The thing I don't like about wind generators is that they might slow down the wind and cause climate changes over a large area. My fear of that is slim, however, and easily overridden by practicality. ;) – Arlen Beiler Jan 2 '11 at 13:07
Besides, if you put them in the desert you won't have to worry about that anyway. – Arlen Beiler Jan 5 '11 at 12:55
@ArlenBeiler XKCD has addressed this – Phil Frost Jan 10 '13 at 15:17

I built this and it works on a small scale. Tesla did file a patent for this it is called the utilization of radiant energy apparatus. it works by collecting waves and particles giving off from radiant energy. the higher you put you antenna the better it would work and the more of those modules you have will increase the power. Also I used a piece of shiny polish metal which works much better. I have worked on this project for a few weeks now and am already proving all you people who say this is false wrong.

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and what kind of power energy are you getting out of your apparatus? Can you light a LED with it? – angelatlarge May 3 '13 at 5:03

first of all. the question from the beginning was about collecting the positive ions from the atmosphere and creating a usable amount of sustainable energy in the form of dc current using the earth as a ground. Teslas radiant energy generator has nothing to do with this type of current generation. Tesla did invent this method as well though. It also has nothing to do with the tesla coil or wireless tranfer of electrical energy. This atmospheric positive ion generator that is the subject of question is in fact possible and has been accomplished for a total power generation of 2.6kw at 300meters high. for ever foot higher you go from the ground the potential energy of 19volts is created. until you reach about 300,000 volts about 10km high. yes the volts are high but the amps are in fractions. By charging capacitors can use transformers to reduce your volts to a working power supply. and because a capacitor is made to release all the energy at once the amps can also be reduced. the simplest way to put your conductor antena 10km in the sky would be with a huge mylar foil helium ballon held down withthe apropriate guage copper wire. because the balloon is conductive its self theres no need for an antena. Every invention Tesla came up with turned out to be somewhat plossible if not 100%. The personal home power generation is a very real ability for this, but for comercial power plantoutput it would have to be so emense it would not be realistic. its all about the conductive ability of the ion antena or weather balloon to channel the current down the main line. Ive notice that theres a lot of sceptasism with the voice in this discussion. Its been prooven by several men already and is scientifically supported. Also you dont have to worry about destroying the ozone or anything. for one the sun amits so many ions into our atmosphere they would be completely replace instantly. and the with lightning strikes decreasing. ya right. sense the ions are replaced by the sun instantly you'll never have an effect on them. Lightning strike when the air get to a high enough humidity factor that it allows the atmosphere to ground an discharge obruptly. so sorry the o2 & o3 levels wont ever be effected. cfcs in spay cans refregorant co2 emissions and volcanoes are bout the only things to effect that. You can find every thing ive said online at site like hyperphics and wikapedia. lol. Dont take my words for it. look it up.

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Seriously, this is a mess, can you break the wall of text and add some much-needed capitalization? – Renan Aug 9 '13 at 1:10
"Its been prooven by several men already and is scientifically supported" <-- Care to cite your sources? I would down vote because your answer doesn't address the OP's question, but (un)fortunately I don't have enough reputation here. – Joel Cornett Mar 2 '14 at 18:44

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