Siphoning Energy From Power Lines

The discovery and implementation of alternating current revolutionized the entire world little more than a century ago. Without it, we’d all have inefficient, small neighborhood power plants sending direct current in short, local circuits. Alternating current switches the direction of current many times a second, causing all kinds of magnetic field interactions that result in being able to send electricity extremely long distances without the resistive losses of a DC circuit. The major downside, though, is that AC circuits tend to have charging losses due to this back-and-forth motion, but this lost energy can actually be harvested with something like this custom-built transformer.

[Hyperspace Pilot] hand-wound this ferromagnetic-core transformer using almost two kilometers of 28-gauge magnet wire. The more loops of wire, the more the transformer will be able to couple with magnetic fields generated by the current flowing in other circuits. The other thing that it needs to do is resonate at a specific frequency, which is accomplished by using a small capacitor to tune the circuit to the mains frequency. With the tuning done, holding the circuit near his breaker panel with the dryer and air conditioning running generates around five volts. There’s not much that can be done with this other than hook up a small LED, since the current generated is also fairly low, but it’s an impressive proof of concept.

After some more testing, [Hyperspace Pilot] found that the total power draw of his transformer is only on the order of about 50 microwatts in an ideal setting where the neutral or ground wire wasn’t nearby, so it’s not the most economical way to steal electricity. On the other hand, it could still be useful for detecting current flow in a circuit without having to directly interact with it. And, it turns out that there are better ways of saving on your electricity bill provided you have a smart meter and the right kind of energy-saving appliances anyway.

108 thoughts on “Siphoning Energy From Power Lines

  1. When I was doing cable work, we had what were effectively little wands that had an induction coil and a simple circuit in them that could detect if a conductor was energized without contact. All of them had a little light of some sort and some had an audible alarm. They are available at hardware stores and in line with quality and ratings start at about $10. I saw one that had a digital readout that estimated current, similar to how some multimeters do it.

    1. Yup. We call it a dead stick, for some reason. Don’t trust it if it doesn’t light up. Battery contacts in them sometimes fail. Don’t know why they didn’t think to put a battery power indicator in them. I always check both sides of the switch, interrupter, or disconnect for a positive reading first, then a meter reading between all phases and ground. Still have all my fingers, and aim to keep it that way.

      1. Maybe with a tuned inductor like up top, you could make one that doesn’t require a battery and just harvests its energy from the line being tested. Should be a bit more trustworthy

        1. One reason for the battery powered tic testers is it needs to sense power at a point were there is no load. Like the end of a loose wire with nothing connected to it. Can’t harvest power from a dead end wire by induction. Another reason is a battery powered tic tester can detect an energized extension cord, even with a load. The hot and neutral in close proximity will cancel each other’s fields. As one magnetic field in one wire grows, the other shrinks. This is how a GFCI works. A ground fault is detected by the imbalance. The magnetic field in hot wire won’t be fully canceled by the one in the neutral. Current is induced in the coil that is used to trip the GFCI. This is why an amp meter clamped around both the hot and neutral gets no reading. If you do, then there is a ground fault. A tester that works by harvesting power from a cord with the hot and neutral too close together wouldn’t work.

      2. The ones I’ve seen always beep and light up when you initially turn them on to confirm the battery is working.

        Still check with a light or meter if it’s critical, but those are nice for a quick initial check.

      3. Little experiment: Take a coil with lots of thin windings and with some alligator clips connect it to sensitive in ear headphones. Hold it to the drywall near a lightswitch and you can hear the AC. With some luck (or a good setup) even follow the line.

    2. “Alternating current switches the direction of current many times a second, causing all kinds of magnetic field interactions that result in being able to send electricity extremely long distances without the resistive losses of a DC circuit.”

      I feel stupider for having read this. The truth isn’t complex – the power carried by a wire is v * i, but the power lost due to wire resistance is proportional to i * i. So using a high voltage and lower current reduces the power lost relative to the power carried by the wire.

      This is essentially independent of whether the current is AC or DC (*). AC has traditionally been preferred as it’s simple to step the voltage up for transmission, and back down for distribution and use using transformers (that admittedly have magnetic field interactions inside). However the same power transmission advantages hold for high voltage DC power distribution too.

      People already use DC to DC converters (that admittedly also have magnetic field interactions inside) to allow more power to be sent over thinner or longer wires. Stepping up from 12v to 48v DC reduces the power lost in the wire by a factor of 16 – and DC to DC converters are pretty easy these days. Same reason PoE uses high voltage DC to get useful power transmission over very thin Ethernet wires.

      (*) Pedantic note. DC can actually be better for power transmission due to the skin effect.

      1. Yes, that statement made me cringe as well.

        One more reason for why using AC may be beneficial (especially for last century stuff) is arcing. The AC zero cross causes the arc to break down fairly fast. You can see this with electromechanical relais, where the rated DC current is significantly lower than the rated AC curent.

        DC/DC converters have to different applications, voltage conversion, and galvanic isolation (Sometimes both are combined). Voltage conversion can also be done with e.g. switched capacitor circuits, where the energy is stored in an electrical field, not a magnetic field. As far as I know, galvanic isolation always uses a transformer.

        1. Another reason is that transformers are passively efficient, while DC-DC converters have idle losses.

          Most of the infrastructure is only rarely used up to capacity, but it has to be sized up to the capacity it was required to handle. This is like powering an Arduino with a 500 Watt ATX PSU: the unit may have 95+% efficiency rating at nominal output, but using less than 1 Watts the real efficiency is terrible, probably less than 10%. Now duplicate this in every sub-station and distribution transformer and you start to see the problem.

          1. To put it more precisely, a transformer does have idle losses but it “throttles” down better than a DC-DC converter without the switching losses. A typical distribution transformer can have 1-2% loss at 30% load and 0.5% loss at full capacity.

            Switching mode power supplies, even good ones, can easily have 10x the losses.

        1. Submarine power transmission in salt water uses DC because of inductive losses: Salt water is conductive, and acts like a shorted turn in a transformer when AC is used. DC doesn’t have this problem because its magnetic field is static.

      2. >and DC to DC converters are pretty easy these days.

        In the small to intermediate scale. When you’re dealing with bulk power transmission on the grid at high voltages though, it becomes not so simple. There is no ready source of very high voltage DC for transmission. Every rotating generator makes AC by nature and DC sources such as solar panels are not easily wired up in series to make dozens or hundreds of kV directly.

        You can step up the DC voltage, but the converter is structurally very similar to an inverter anyhow, so you can just omit the unnecessary high voltage rectifier and transmit AC instead.

      3. Not just the skin effect either. DC can be better for power transmission because it doesn’t have inductive losses when other conductive materials are nearby. Nearby coils aren’t the only thing that can steal power. Metal structures will steal power, water (that isn’t too pure) can steal power, metal vehicles, even the ground can steal power (one reason why long distance transmission lines are kept so high up). Technically even power lines that are close together and out of phase can short out small amounts of power to each other. (“out of phase” in this context is also influenced by distance and wavelength, and since 60Hz AC wavelength is so long, the distance required for zero inductive losses between lines would be…5,000 kilometers, while maximum losses would be half that (2,500km). So basically, there are definitely some inductive shorting losses between high voltage transmission lines, but they are close enough together that the losses are probably fairly small. That’s still more than the 0 inductive losses you would get with DC power though, especially over very long distances.)

        I suspect that with modern DC voltage stepping technology, we could significantly improve transmission efficiency by using DC for long distance transmission.

  2. „Alternating current switches the direction of current many times a second, causing all kinds of magnetic field interactions that result in being able to send electricity extremely long distances without the resistive losses of a DC circuit.“

    — Well, Mr. Cockfield, that is a good and bad news; what we are supposed to use in order to limit AC current if resistors do not work for AC? Should we start stockpiling chokes now?

  3. ..wait, you’ve never heard the story of the bloke that shoved in some 20 kilometres of wiring around a 44 gallon drum, shoved it under a high tension 330kv line – and then went to court over stealing power? I thought that this was well known.

    1. Apparently Google doesn’t “know” that. I tried six variations of your description above and got ZERO hits other than your statement here being the top hit. Another urban (not so) legend? Unless you can come up with a link?

        1. The cited “reference” refers to a “story” someone heard in the 90s, so it’s more heresy and not a reference. No where did I find a primary reference to the event.

    2. I thought itwas the one about a guy who fileld his garden with wire loops tuned to a few frequency bands and “siphoned” a small amount of power from nearby RF communication. He did it to the extent he was taken to court for blacking out mobile phone, tv, emergency and all other RF comms for a wide area, his setup absorbed so much energy from the signals there was none left in them for communications receivers to pick up. I can’t imagine he got anything approaching a useful level of power from it though, the whole point of RF comms is they can be received without needing all that much power flux (Watts/sq metre) at a receiver.

        1. Inverse square law applies to free space propagation. Coils sucking power out of the air and shielding in its path will attenuate the signal

          It is perfectly normal for things to black out signals down range from them. Mountains and groves of trees are quite effective.

    3. Yeah my uncle told me that one, and also the one about the guy who strapped solid fuel boosters to the roof of his Trans Am and got launched into the side of a cliff in New Mexico. Classic tales.

    4. Technical details are wrong. That’s not how you would do it.

      You’d need an insulated elevated line in parallel with the high tension line. Running a significant fraction of a 60 Hz wavelength.

      The story I know to be true involves a EE and a 100,000 W FM radio transmitter in Colorado. He put up poles and constructed large loop antennas to harvest the power. It went to court, he won and the FM station wound up paying him what he asked for his land. Occurred in the late 80s IIRC.

  4. “Without it, we’d all have inefficient, small neighborhood power plants sending direct current in short, local circuits.”

    You’re talking about solar panels, right?

    1. Distributed power generation is “inefficient” for centralised, private, power- and money-hungry, vulture capitalist energy monopolies.

      It’s definitely not inefficient when the national grid is down, e.g. due to natural disaster.

        1. Post again when you maintain an off grid power system with an availability comparable to your local power supplier. (Hoping you’re not posting from the turd world, some ‘workers paradise’ or a war zone.)

          Grid is pretty resilient. Much better than any single generator. Least resilient part is the line to your house, no redundancy. Hospitals etc are usually hooked to two substations.

      1. >It’s definitely not inefficient when the national grid is down

        Well, efficiency won’t matter since “distributed” in terms of things like solar and wind power depend on the national grid to distribute. They can’t operate in “island mode” without heavy support from batteries, which in turn are dependent on centralized, private, power- and money-hungry vulture capitalist mining monopolies overseas.

        If you want locally independent distributed power generation, start chopping wood and digging up coal.

    2. Your very very local house wide Solar powered DC grid is massively more efficient than the current HV AC transmission for most people – houses are small, the cable runs are tiny, so even if the losses were truly huge % wise* they would still remain small losses overall. AC transmission grids can easily beat transmitting over any real distance in DC but distances that are so small they approach zero length in comparison not so much.

      *which they are not unless you are really really stupid in building your little DC house grid

      And if you mean efficiency of resources in vs output energy at the consumer it gets even worse for the AC grid in many ways – the solar panel is in effect prepaid but functionally approaching limitless energy output over its lifetime so by that measure of efficiency it trounces anything else. The AC grid at least for now is still very reliant on some form of fossil fuel in nearly every nation – an ongoing cost to extract, refine, and ship it, and it still had to have a huge prepaid cost to build the infrastructure.

      NB I am not saying AC grids are a bad thing in any way, just that your remark about solar is rather erroneous. Especially as any long distance transmission from the DC solar generation is done in AC on the existing grid infrastructure…

      1. Also meant to mention I was strictly thinking of ‘low voltage’ 12 to perhaps 48v in DC terms – that is the ballpark range of what people actually do with their solar and battery setups…

          1. Not really. The transmission distance from my car’s 12 Volt battery to the starter motor is less than a meter, and yet the cable has to be a thick braided copper ribbon to supply a measly 1 kW of power.

            If you’ve ever done car audio, in order to get power from the battery to the back of the car where the subwoofer amp is, you need cabling as thick as your thumb or else the voltage starts to sag and you get audio clipping. Hence the big capacitor banks that are added to compensate.

          2. Thick cables cost more, but in terms of making your system efficient to run are meaningless – those same cables are almost certainly still going to be in use in decades time (if AC wiring in old buildings around here is anything to go buy quite possible century+) so the cost of their creation is rather meaningless spread over all those years as well.

            I’m not saying and have never said the low voltage DC will best High Voltage grid efficiency once you start transmitting over serious distances. But when you are talking usually 10’s of kilometre for the grid vs maybe 1/20th (and probably much much less than that) of a kilometre for the home solar…

          3. Also remember there is more to system efficiency than just the transmission loss – power conversion losses add up too, and as most household devices these days are DC <24V starting nearer that ballpark is a good thing for transformer complexity and efficiency!

          4. Most home appliances that run at low voltage are either low power, or the power cable is short.

            Transmitting the same power at 24 Volts DC instead of 240 Volts DC for comparison’s sake requires 10x the current, and since power loss in the cable is proportional to the square of current, you need 100x the cable cross-section to achieve equal efficiency for an equal cable run. Even if you compromise and allow twice the loss^, that’s still 50 times the amount of material.

            That’s not a trivial amount of copper if you consider replacing your house wiring, since there are hundreds of meters of wire even in a small apartment, let alone in a house.

            ^(household cables are not sized for efficiency, but for heating at the rated amperage because they’re enclosed inside walls and can start fires. If you allow twice the loss, you have to de-rate the cable which moots the point.)

          5. The whole point though Dude is that the cable runs are not equal! You are comparing a handful of meter in the low voltage DC in total from source to storage/consuming device vs 10’s of KM just to get to the doorstep and then that same handful of meters. That is a great many orders of magnitude extra.

            Also these days Dude even your vacuum cleaner is generally a DC device internally, if it isn’t actually battery powered in its own right. Common household devices on the whole now are all rather low power with all the improvements in efficiency. About the only ‘High power’ devices that the 100-240 VAC of most grids make sense for in most households are some (and only some) of the cooking appliances, and maybe the climate control devices (but many places don’t need much energy put in for that, and many of the places that do need it will be using other fuel sources over electric as it stands for that anyway).

            I agree there are engineering challenges to making the low voltage DC grid work, and avoiding overheating is absolutely one of them. But it isn’t an impossible or even particularly expensive problem for infrastucture that will last decades+!

      2. All obstacles in power transmission boil down to power loss. One way to defeat that is raise the voltage to lower the current needed so there are lower IV (power) losses for a given R in distribution. That’s why electric cars routinely use voltages of 300 V or more (and exposure is more deadly). The “long distance” issue arises when power needs to go further than what produced a voltage loss of more than about 5%, since the item being powered probably won’t work efficiently through a wide voltage range (unless, with MODERN electronics you add a voltage booster DC-DC converter). That’s where AC comes in handy, since then you can do voltage step up or down with a transformer. There are even voltage regulating transformers that use saturating cores.

      3. > houses are small, the cable runs are tiny, so even if the losses were truly huge % wise* they would still remain small losses overall.

        Grid losses are in the range of 2-12%. Usually around 3-6%

        Meanwhile, transmitting 1500 Watts (a tea kettle or a vacuum cleaner) at 12 Volts requires 125 Amps. A copper wire 10mm in diameter and 20 meters long, counting up both ways, would lose about 140 Watts for that amount, or 8.5%.

        You can very easily exceed the transmission grid loss with low voltage DC, over very short distances, even while using ridiculously thick wiring. Compare: normal household AC appliance cable is 1 mm in diameter and rated for 15 Amps intermittent use, which is good for about 3500 Watts at 230-240 Volts.

    1. Where’s the “tuning” come in? That implies AC. There is probably some variability, but my supersensitive magnetometer doesn’t “see” that. Does your compass vibrate? Then maybe you’re living in a sci fi or horror film as we “speak”?

  5. “provided you have a smart meter ”
    Don’t confuse knowing power usage with actually reducing it. Don’t be like governments around the world who think if we monitor power we magically reduce demand, the only answer for a future of clean power is a massive nuclear reactor building program which should have started years ago but for which starting NOW is an acceptable alternative.

      1. Our greens (not Australia) successfully lobbied for the reduction of peat and coal in energy production to the point that these industries have now almost vanished. Of the remaining power sources, the greens also oppose hydroelectric power (no more dams) and nuclear, leaving biomass which is basically whatever forestry waste there is – except the greens also strongly oppose forestry to preserve natural habitats and biodiversity. That leaves only solar, which is non-existent and doesn’t work for half the year, and wind power, which is capable of meeting under 10% of the demand. In essence, the greens oppose EVERY significant power source we have.

        That is, until last winter’s power crisis when the prices soared up 1000% and people were literally starting to freeze in their homes. They took such a bad hit in popularity that you could literally hear the flapping of turning coats as they raced to support nuclear power as the “least of the worst” option.

      2. Aussie average power prices are insanley high for a nation with plenty of coal.

        Buisness’ pays 50 cents a kWh, granted those are Aussie cents. About 35 cents in real money.

        Coal is not dying due to economics.
        It’s been regulated away and Aussie voters are getting what they deserve.
        Good and hard. No lube, not even vegemite.

  6. “Without it, we’d all have inefficient, small neighborhood power plants”
    You realise that looking back on it today, Edison won. The longest range highest powered interconnects (cross contiental and/or international) are often DC transmission nowadays, this way they don’t have to sync up the phases of generators at power plants thousands of km apart.

    1. In Edisons day we did not have powerelectronics to do the DC/DC conversion needed to increase or decrease the voltage. The sync of generator is actually a simple way to keep track of supply vs demand of power. If the frequenzy goes up it means that the power used is less than the power generated. And if the frequenzy goes down it means that there is a need to produce more power.

      1. HVDC lines are usually only built to work in one direction. They’re not efficient to operate “idle”, i.e. when there’s varying power flow in either direction with occasional zero flows, because it takes considerable power to run the converters.

        They’re built to transmit power continuously in one direction, close to capacity as much of the time as possible. The supply and the demand is planned ahead.

  7. AC has a transmission line advantage?? i thought high voltage had the transmission line advantage, and AC was helpful to that because it lets you build a transformer without first building an oscillator.

      1. College ain’t what it used to be, and it’s a gajillion times more expensive. In a few decades we are going to reap the rewards of this, and nobody seems to be talking about it. They aren’t turning out people who meet minimum competence, let alone who are capable of pushing the envelope

        1. Sure we are.

          We’re just also turning out 9/10 indoctrinated morons. Don’t hire them.

          First filter, BAs go straight to the circular file. Don’t even need to read the word ‘studies’ in their major, gone way before that.

  8. High voltage has the advantage of lower current for watts consumed which outweighed the other disadvantages and you can step it back up to the original voltage to compensate for line losses

  9. Make the coil bigger (around 50′ in diameter) burry it under a very high voltage tramsmission line, and you can get over 120VAC out. This is something mid west farmers have been doing for years. Much to the dismay of power companies. Yes, power companies can get a court order, and make you dig up the coil. Yes, they can detect this happening.

  10. Other than you, nobody is saying this is “Free energy” and your name calling is self-descriptive. Anybody who watched even just the intro to the video already knew more than you.

  11. “On the other hand, it could still be useful for detecting current flow in a circuit without having to directly interact with it.”

    They make actual clip on current meters for that purpose, and a linear Hall Effect sensor would do the job better if you wanted to roll your own.

  12. Why building the world’s worst transformer when you can use wind more effectively?
    Take an old stepper motor, fix a house fan propeller to its shaft and let it spin. the amount of energy you can get is a huge multiple of anything that the article claims it can be extracted from power lines.
    Don’t believe me? Then take two similar stepper motors, wire them in parallel, ie every wire of the 1st to the corresponding wire on the 2nd, color by color, then grab one of the shafts and rotate it, the 2nd motor will “magically” follow. Driving a stepper motor requires serious power; if you let the wind do the work you can easily recharge batteries or drive small lights with them. Now go dismantle some old printers and repurpose all those steppers!

    Note: the experiment with two steppers is real and can be immensely helpful for teaching to kids. Consider showing it if you teach in classes.

  13. 1) the farmer in question was probably actually powering gas-discharge tubes at severly reduced current/brightness in complete darkness IF that myth is true at all… in his attic… where most people do not have electric lights installed and thus a super dim glow may actually be borderline usefull for those who like (to smoke in secret). calling them lightbulbs was a way to get street cred (before social-media), making people think he was stealing 100’s or even 1000’s of watts powering incandecent lightbulbs when he was actually stealing more like 100’s or 1000’s or MICRO-watts, to power neon andor flourocent tubes at severly reduced brightness.

    2) the only truly known case is where a guy stole from a radio station, he most likely got the result of # 1).
    i believe the only way he was caught was not by blackinbg out communications per-se, but causing the need for an involved costly and time-consuming re-tuning of the ENTIRE transmitter’s output section, requiring new inductors… custom ones to handle the 50000v and 1000000000hz every time he switched his theft on and off or varied his load, this is akin to contamination or preventing a copmpany from operating and is not about the 1 or 2 cents of actual energy, im sure if he had asked they would have gifted him with two or three button-cell batteries that would contain 10x or 100x or more energy

    3) the magnetic fields at half a million volts and 100 amps is the same as 120 volts and 100amps, you’d get the same result as this project… again too dim to be of use aside from (wonderful) mood-lighting in a (smokey?) unlit attic

    4) there might be an almost usefull way but it requires an electronics knowledge that far-surpasses bailing-wire metal-drum and insultaing-sheet, and works on (edit: feeds-on) the existing ELECTRO-STATIC losses, NOT magnetic. it requires a picture-tube television flyback transformer withOUT any rectification diode(s) such as from an ancient tv or just remove the diode with a hacksaw. (ironically simillar wire length as this project?) the result of this DEPENDS ON THE WEATHER and surrounding environment, ie humidity and nearby trees. it is based on the fact that when you “hear” the electricity’s HUMMING, SIZZILING, and CRACKLING noises… 2 of those 3 noises are NOT 50Hz/60Hz… and are MUCH more likely to be compatible with such flybacks, unlike the 60hz. after all, if you stand underneath a half-million volt line and hold onto a neon power-indicator and touch the other wire to your bike youll see a severly dimm glow WITHOUT the tv flyback! … now imagine it being 300x brighter, might need a more powerfull neon tube, or maybe it could power other stuff now that its 170v or 340v and can maybe be fed into a normal SMPS transformer (just the high-frequency transformer and diodes/caps) to get something else powered. however i would not believe for a second that a smartphone could actually be charged… while on. maybe just tricked into flashing the charging indication ie powering the charger-present sensing. enough to make money on youtube, or go back to my above cases # 1) and 2)

    for 4): this energy can and DOES cause deep-tissue burns with repeated or constant exposure, a paper-cut on the toe with wet shoes WILL be felt as a charlie-horse-like tingle. so the air is must be breaking down (ionizing) as i powered this same neon indicator at home and calculated between 10 and 100 megaohms… but air is normally way way way more resistive to the point of futility-of-measurement.

  14. First, Congratulations on building a current transformer. Guess what happens when the magnetic core saturates due to a power line going down resulting in a large current surge passing through your current transformer core?

    “„Alternating current switches the direction of current many times a second, causing all kinds of magnetic field interactions that result in being able to send electricity extremely long distances without the resistive losses of a DC circuit.“”

    The resistive losses are in the wire. Want less losses for the same voltage source? use lower gauge wire, or parallel the existing wire with another one (both of those things reduce the effective resistance of the wire between the source voltage and the loads).

    High voltage is used to handle VOLTAGE DROP at high current levels. Vdrop = Iwire * Rwire. The R is the wire, it is fixed per gauge / length of wire. Want to drive more current over the same R? need more voltage to do it.

    Alternating current for utilities follows a sinusoidal pattern for current flow between its source contact and return contact, continuously going from 0 to a + voltage peak, back to 0 then to a – voltage peak, back to 0 and so forth.

    The main benefit is that one can easily increase or decrease the voltage of a power line with a transformer. To do this with DC requires additional high power circuitry, more complex than one component.

    DC as a small local, decentralized source DOES make sense — there is no need for synchronization to the AC mains frequency. Synchronization for AC sources prevents one AC source from becoming a load to another AC source. Only thing DC sources of varying voltages need is a rectifier to prevent that source from becoming a load.

    1. > High voltage is used to handle VOLTAGE DROP at high current levels.

      No, high voltage is used to handle power loss due to resistance. Power loss is I ** R, doubling the voltage halves the current, so you can move the same amount of power over the same wire with a quarter of the losses.

      1. No, high voltage is used to handle the voltage drop over wire distance distance. Vdrop = Iwire * Rwire.

        Power loss across R = I*I*R

        Power loss across R also = V*V / R

        There is no free lunch in power dissipation.

  15. “causing all kinds of magnetic field interactions that result in being able to send electricity extremely long distances without the resistive losses of a DC circuit” — Sorry, but AC has EXACTLY the resistive losses of DC, PLUS reactive losses of its own. I^2*R does not have a frequency term.

    1. Yeah, technically we reduce the resistive losses by taking advantage of the ability to change AC voltages much more easily. We aren’t getting less resistive losses. We are converting the voltages so that we avoid the resistive losses of lower voltage DC. That said, while AC voltages can be changed passively quite trivially, modern technology has provided active voltage stepping for DC power that is quite efficient. I’m not certain AC is still better than DC for long distance transmission. If we can step up DC to the same long distance transmission voltages we use for grid AC power, it should be significantly more efficient, because it avoids the reactive losses inherent to AC. It would also use far less copper than those massive high voltage AC transformers, which could potentially dramatically reduce up front equipment costs and also reduce the currently absurdly high copper prices by reducing demand. Oh right, and on top of that, DC doesn’t have the skin effect, so long distance DC transmission lines could be significantly smaller, further reducing the copper required. (Alternatively, by upgrading to DC, we could use existing long distance transmission lines to carry significantly more current, without having to change anything about them.)

      Awesome comment. I had not thought about this in the context of modern switching power regulation, which can step down or up with the right hardware. You got me thinking about power transmission in that context, and now I’m wondering if maybe AC is no longer the ideal form for long distance power transmission.

      All of that said, good luck convincing anyone to change. We’ve got a massive electrical grid that would be quite expensive to convert to switched DC voltage stepping, and some hardware depends on the power being AC. Unless we get that overdue solar storm that takes out all of our long distance power transmission and even many of our short and medium distance grids, no one is going to be willing to spend the resources necessary for such an upgrade.

      1. Here’s a thought experiment:

        What power output do solar panel arrays make, AC or DC?

        If you were to put output rectifiers on wind turbines so that their output was rectified, no need to synchronize each turbine’s output anymore.

        I think it might actually make those systems simpler.

        1. You really can’t just connect rectified AC to a big stable DC grid. Either the source or the destination will have a really bad time. The rectifier makes sure that current only flows when the voltage from the turbine is greater than the grid voltage, and then it passes however much current it takes to force the grid voltage to follow that of the source. Since the grid is much bigger than the source, and we can assume that we do not allow the grid voltage to change very much, then instead of the grid following the source, any difference will be wasted somewhere.

          Back when we commonly used power supplies that were just a transformer connected to a rectifier with a capacitor to smooth out the fluctuations, we quickly realized that it doesn’t scale very well. If you require the voltage ripple to be very small, then you have to draw all of the energy meant to fill up the capacitor to last the next cycle during the very short time that the voltage is very close to being flat, which is at its peaks. This means terrible power factor, and you end up distorting the waveform (snubbing the peak) because in actuality the amount of current it would take to deliver all the energy in a quick pulse is unrealistic.

  16. Somewhere I have a photograph of my father circa 1960 standing under some high tension lines holding a glowing fluorescent tube over his head (lit by the electromagnetic radiation). The photo is a bit more dramatic than reality due to the conditions it was shot with (at dusk) but I often amazed many of my young friends with the same trick under the lines near our house. That photo lead the ‘Bureau of Radiological Health’ where he was a research engineer (later to become the E.P.A.) to launch a huge gov’t research project into the health and safety of high tension lines.

  17. “Without it, we’d all have inefficient, small neighborhood power plants sending direct current in short, local circuits.”

    Which would be incredibly robust! All it would take is a single solar storm hitting the Earth with the right polarity, an event which happens about once a century, and which we are now overdue for, to take out most or maybe all of the U.S. and European electrical grids (along with many other countries, though parts of Canada have been hardened against that). That would throw us back to pre-1800s technology, and it would take Europe probably 15 years or so to recover and the U.S. no less than 20 years. (The equipment that would be destroyed takes 2+ years to manufacture, and the only plants that do it are in Europe and manufacture at small scale and only to order. As such, Europe would get first dibs, and we would be stuck waiting for them to get back up, just for them to recover the capacity to ship them overseas to us.)

    That said, I would prefer highly distributed AC generation to DC, because long distance transmission isn’t the only benefit of AC. Modern electronics use a wide range of voltages, and AC is much easier to convert to whatever voltage you need.

    (Also note that higher efficiency doesn’t necessarily mean lower cost to consumers. Large scale power generation can’t take advantage of energy sources that aren’t in large supply in a centralized area. Small scale power generation can take advantage of resources that are so spread out that they aren’t economical for a large centralized power plant, where smaller local generators can. Wind and solar power are great examples here. Both of these require absolutely massive amounts of land, because they are so sparsely spread. The environmental impact of these is far greater than a coal or nuclear power plant, which uses ores extracted from one or a few locations that are very rich in those. On the other hand though, it would be much more economical and environmentally friendly for every house to have solar panels on the roof. The environmental impact of highly distributed solar power is far smaller than that of nuclear or coal power. And the same is likely true of wind power as well, though the capital cost for wind power is much higher than for solar. Solar is great for individual houses. Wind would probably be ideal for neighborhoods. An industrial scale wind turbine might average around 0.66 to 1 megawatt (rated for 2 to 3, with a 33% efficiency factor for the region). That’s enough for 26 to 105 homes (26 if each is constantly drawing their maximum of 200 amps, and 105 if they average 50 amps and the turbine has some kind of storage to store power during lows so that it can keep up during peaks). That’s several neighborhoods for a well designed system. Smaller scale wind turbines that are rated between 0.5 and 1 megawatts would be perfect for individual neighborhoods, with sufficient capacity to power around 25 to 30 homes, with appropriate storage to smooth out low and peak demand times. Again, cost can be lower, because the turbine can be setup in a local park instead of a utility company having to buy up, clear, and maintain many acres of land to put the turbines on.
    There are also energy sources that we don’t currently tap for power, because they aren’t practice for massive scale centralized generation that would be quite economical for small scale distributed power generation. Basically, well designed small scale power generation actually has the potential to be cheaper in the long run, because it can take advantage of energy sources and spaces that aren’t practical or cheap to use in large scale, centralized power generation. In fact, I’m currently working on discovering and developing power generation technologies that take advantage of these untapped, highly distributed resources.)

  18. I remember seeing an old schematic years ago of using a primary of a transformer in series with a load. When a switch was closed, current flowed through the primary to activate the device. Current was induced in the secondary coil to activate an LED. An example would be turning on a light would activate a indicator in a monitoring panel. To control heavier loads than a LED, an optical isolator can be used to pull in a relay to operate the load.

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