Getting power from transmision lines electromagnetic field
Getting power from transmision lines electromagnetic field
(OP)
Hi folks,
In developing countries, corridor of transmission lines run nearby small villages with no electricity. This seems to be very unfair to people from those villages.
There is an ideia of getting power (1-2kW) from the electromagnetis field of the transmission lines to feed those village. I wonder if somebody has information on this kind of development.
Best regards,
Herivelto Bronzeado
In developing countries, corridor of transmission lines run nearby small villages with no electricity. This seems to be very unfair to people from those villages.
There is an ideia of getting power (1-2kW) from the electromagnetis field of the transmission lines to feed those village. I wonder if somebody has information on this kind of development.
Best regards,
Herivelto Bronzeado






RE: Getting power from transmision lines electromagnetic field
Don't even _think_ about doing it.
Mike Halloran
Pembroke Pines, FL, USA
RE: Getting power from transmision lines electromagnetic field
Besides it's stealing clear and simple.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Getting power from transmision lines electromagnetic field
Such a practice is unlawful in the USA, I would be hesitant to consider such a practice considering it may be against the law and concidering the negative safety aspects of it as well.
Tom
None of us is as smart as all of us.
RE: Getting power from transmision lines electromagnetic field
Can't really see the "unfairness" in having a power line nearby and no power. I have a rail-road not far away. Lots of cars, fuel, frozen food, wine, timber. And I don't get any of it...
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
I looked into the feasibility of providing power in a similar situation in Canada years ago. You can extract small amounts of energy by inductive coupling, but not enough to service a village.
They method needed is an economical transformer. I went looking for a suitable used transformer.
I considered having a used transformer rewound for the voltage needed. What I found was that for any given voltage there is a minimum size transformer. It has to do with the size and physical strength of the windings, and the size of the tank to provide space for the high voltage bushings. If the winding conductor diameter is below a certain size it will be destroyed by the first fault. It may not even survive energization stresses.
With a 133kV transmission line past the settlement, the smallest transformer that could feasibly be used was worth more as scrap metal than the village could afford.
I suspect that the same economics will still prevail.
When a line is grounded out for maintenance there will often be a voltage and current induced by parallel, energized, lines. There is often enough energy to kill men and livestock, but not much more. And also the extremely high source impedance will make regulation virtually impossible.
However, a challenge for some of the Gurus here: If a fourth line was added, parallel to one of the existing phases, how much energy could be linked per mile?
Possibly a distribution type transformer may be designed so that the induced voltage is kept to a value that the transformer will endure.
The next hurdle is controlling the voltage without excess waste.
As an idea, how about several miles of parallel line with a transformer at each end. One transformer will supply the load, and the other will have switching on the secondary to control the current (and, by inference, the voltage) at the other transformer depending on the load.
I haven't had my second cup of coffee yet. Maybe I will come up with some more suggestions later, but maybe not.
Back to you, Gentlemen.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Getting power from transmision lines electromagnetic field
I respect your (always) positive attitude, Bill. But I cannot play this game.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
Respectfully, I believe that you may have misunderstood my intent. I was not advocating a free lunch or stealing power.
I was suggesting that we discuss a possible "outside the box" solution whereby utilities could supply and charge for small amounts of electrical energy to small settlements.
The capital cost of tapping a transmission line starts in the millions of dollars. Out of the question for small communities.
I am thinking in the range of possibly 10 KVA to 50 KVA.
A line parallel to one phase would be an air core transformer in parallel with a capacitor. While the energy available would be small, it would be several times greater than the energy induced in a parallel transmission line.
I am thinking something along the lines of two 15 KVA x 35 kV distribution transformers. The transformers would each have one high voltage bushing grounded, and have the other bushings joined by a length of conductor a safe distance from one phase. One transformer would supply the load and the other would control the voltage by varying an impedance across the secondary terminals. Similar to a distribution transformer used for high resistance grounding of a high voltage transformer.
I agree with you, Gunnar, stealing power is not proper.
However I see this as a challenge to supply small amounts of power in a way that it may be safely used and sold at a reasonable price.
I usually agree with you, Gunnar. When I don't agree with you, I still respect you. I feel that way about most of the regulars here.
Respectfully
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Getting power from transmision lines electromagnetic field
For those who did not get my point at first glance, I am sorry for not make myself clear.
For your information, I work for a state owner utility in the Noertheast of Brazil (Companhia Hidro Elétrica do São Francisco - CHESF, www.chesf.gov.br) that generate arround 10 GVA) and supply almost 60 million people.
We have more than 18.000 km of transmission lines runnig across an very poor and dry region with a lot of very small villages without electricity and with dificulties to get water.
There exist a governamental program in Brazil called "Light for All" that intend to supply electricity to arround 12 million people that live in remote villages without it. I am talking about a basic need (electricity)that should be the prime mover to run other "bussiness" in this poor region, mainly pumping water from wells.
Itsmoked, if you were aware of the situation of this region I am talking about, I think you could propose a program like "Water for All", where peolple could access water from passing pipelines. At least, the planners should think in a way to give access to all those living nearby a pipeline or a tranmission line. I am still talking about a very basic need - water and electricity.
As Bill said, I am not advocate to steal power or (taking a ride in your saying) water. What I am trying to know
is how can we get energy to supply safely (but not reliable) a remote small village neaby transmission lines.
How to charge for this service, control the supply voltage and protect people and equipmente is another matter that chalenge us.
I would very much appreciate your thought on that.
Best regards,
Herivelto Bronzeado
RE: Getting power from transmision lines electromagnetic field
But, given the fact that the transmission lines usually are three-phase and therefore produce near zil flux as soon as you get a few yards from it. And also given the fact that cables grow and shrink with temperature and sometimes "dance" violently in stormy weather. Plus the fact that line current is not very constant.
Given all those circumstances, I see no real practical solution to this proposition.
One solution could be to let the induced current charge a DC link with whatever power it can suck from the transmission line and feed this highly variable DC voltage to an inverter that produces the needed three-phase - perhaps even single phase AC will do?
I still think that a DG set or a solar panel plus accumulator/inverter would be the better solution. It is standard, it is available, it is proven, it is legal - what is wrong with that?
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
Rather that delve into the ethical issue, let's tackle the physics. There is no "free lunch" when it comes to power, electrical or otherwise. What the proponents of this idea (whomever they may be) are probably thinking is that, by somehow tapping into the EM field they hear of that exists around the conductors anyway, they can extract power without affecting the transmission lines themselves. That is just not the case.
First off, it would need to be an AC transmission line and a lot of high voltage lines are DC. If it were DC, the only way to extract power that I can think of would be to have some sort of coil moving in the EM field and where is the power going to come from for moving that coil? So let's move on to the assumption of an AC line.
As mentioned earlier, in order to extract any usable amount of energy from the EM field, i.e. with a transformer coupling across the lines of force, the transformer would need to be very very close to the lines, essentially an "air core transformer". In fact, it would need to be too close to be done safely; why do you think those towers are so high?
Lastly, assuming you solved that logistical dilema by sacrificing a few brave souls on a wooden platform, now you have the "no free lunch" part of it. When you do successfully couple your air-core power transformer to the EM fields around the lines, they will have an effect on the lines themselves, i.e. the back emf of your transformer will couple to the transmission lines and add impedance. That means less power will flow through those lines to the loads downstream and thus the transmission losses will be increased. Someone always pays for those losses, usually the supplier or maybe in your case, the Government. Nonetheless, it is not "free" and it is definitely unsafe.
So if the Government is truly interested in supplying power to these villages, they will need to tap off of the lines in a safe manner with a sub-station. That is exactly what those are for. Expensive? Yes, but if there were safer ways to do it less expensively, believe me, that would be the standard!
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: Getting power from transmision lines electromagnetic field
Leave it to waross to see the correct intent. (Atta boy.)
I have ot agree with Skogs on the solar angle. There are several good solar powered pump setups available. Solar trackers and MPPT (Maximum Power Point Tracking) controllers to get the biggest bang out of any solar arrays.
Lights are much more coefficient now in LEDs or Compact Fluorescent that little solar arrays can provide a lot of basic night lighting.
I was just given a flashlight that is made for poor/remote countries/people. It provides about 8Hrs of light after a day in the sun.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Getting power from transmision lines electromagnetic field
Hi jraef, As I understand the issue, Bronzeado works for the utility. The challenge is to supply AND CHARGE for small amounts of energy that will not support the expense of a conventional sub station.
Back to Bronzeado's issue. I assume that the amounts of power to be extracted are so small as to be insignificant as far as system through put is concerned.
Any thoughts on how much power we could extract with a bushing CT? Can we push one up to 5 KVA or 10 KVA? 25 KVA will support a fair sized villiage. No electric stoves or hot water, just lights and entertainment equipment.
If we determine that a CT is capable of extracting enough power, then we will work on controlling it. Gunnar's DC link and inverter may work well.
Bronzeado, what are your typical voltages and currents on the transmission lines under consideration.
What range of variation will there be with the current.
BTW, folks, if DG was economically feasible it would have been installed when oil was $50 a barrel, not now at over $100 a barrel.
I spent some time with a solar array in the Moskito Coast some years ago. it left me with a negative feeling towards solar. The new generation of grid tie inverters and net metering are making a believer out of me, but the cost of stand alone systems with battery banks seemed to be excessively expensive to me. Even with a donated system, replacing an average of 20% of the batteries anually is a factor that never seems to be considered. Yes, I know, there are better batteries, but the cost seemed to be proportional so the annual cost was about the same.
And, as for diesel, on the island, generating with diesel, the delivered cost is now $0.42 US per kWHr. The cost of fuel to run a self owned set is about one half of this. Nevertheless, the many folk who have their own backup sets have found that the cost of ownership is over twice the cost of the fuel. They buy energy from the grid and only run their own sets when the grid is down.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Getting power from transmision lines electromagnetic field
RE: Getting power from transmision lines electromagnetic field
On the other hand there is only static wires where there is lightning.
Although somewhat costly Kuhlman makes station power transformers for taps on the transmission voltage (100KVA at up to 230kv).
RE: Getting power from transmision lines electromagnetic field
I remember this being discussed when I was a kid. And that is REALLY a long time ago. The idea is not new in any way. There is no solution to it as far as I know. Why do you think that is so?
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
1. "The challenge is to supply AND CHARGE for small amounts of energy that will not support the expense of a conventional sub station."
2. "...the amounts of power to be extracted are so small as to be insignificant as far as system through put is concerned."
3. "If we determine that a CT is capable of extracting enough power, then we will work on controlling it."
The typical voltage on our transmission lines are 230kV and 500kV. The current varies from 0A to 300A.
Gunnar, I agree with you that the fact that line current is not very constant is a big issue in this matter.
Regarding to the cable "dance" and the null magnetic field, they may be avoid if an "air core transformer" is installed on a isolated platform nearby the lateral cable, with fixed distance from the cable.
Jraej, there will be no "free lunch". People would pay for this service at a price which should take into consideration the poor reliability and quality.
David, during a ground fault in the transmission line, the secondary winding of the coupling device could be short-circuited initially by a varistor and then by a "circuit closer" (circuit breaker). This action will protect the "system".
Cranky108, thank you for the information.
Regards,
Herivelto Bronzeado
RE: Getting power from transmision lines electromagnetic field
RE: Getting power from transmision lines electromagnetic field
It will probably be possible to build an isolated platform and put a piece of conductor close to the transmission line so that varying distance would not be a problem. But the safety distance when dealing with 230 and 500 kV is such that the induction between the "primary" and "secondary" will be very small - if you do not apply system voltage insulation. And then, you could just as well use a transformer. With much better results.
Since I have a set-up to measure inductance between parallel conductors, I modified it somewhat to measure actual induced voltage when running 60 A AC in one conductor and measuring the other. The results are not encouraging. That is the reason why this "Power Line Tap" hasn't been used in practice - even if people have talked about it for at least sixty years (that is how far back my memory serves).
Test results in the attached pdf. Comments invited.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
Gunnar, great!!!
From my point of view, only solar solution in this case.
Regards.
Slava
RE: Getting power from transmision lines electromagnetic field
Consider the familiar configuration of a trefoil arrangement of three conductors on a pole or tower. the center conductor high, in the center, and the other two conductors lower on a cross arm. Now visualize a second cross arm lower on the same pole. The spacing below the first cross arm would be equal to phase to phase spacing. A "pick-up conductor would be run below each phase conductor for a mile or so. I suspect that the results will be much better than Gunnar found in his experiment, but still inadequate.
I am tending towards bushing style CTs installed on insulator strings.
Another possibility, a voltage divider using 35 kV power factor capacitors. The capacitors could have their cases mounted on insulators suitable for the transmission line voltage.
A small 35 kV distribution transformer would be connected in parallel with the last capacitor in the string.
The advantages are;
1, This would help the line power factor slightly.
2, The major components will probably be in stock, the capital outlay for a pilot project will be small.
3, I imagine that the effect of tapping small amounts of energy from a transmission line may be in the order of magnitude of the unbalances resulting from poorly designed transpositions.
Will this work? What will we need for over voltage protection?
Do you see any problems with capacitor banks distributed along your transmission lines, Bronzeado? If we service three villiages, we should not be too unbalanced.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Getting power from transmision lines electromagnetic field
RE: Getting power from transmision lines electromagnetic field
You seem to live in a country with some mysterious inverted inflation. You started with a few cent's worth of tips - and now you are down to two millicents? Remarkable!
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
My 2 cent.
Actaully, I understand the Herivelto situation.
Solar is good solution, but is expensive now.
DG is expensive and in additional is request fuel and maintanace.
Taping on the 500kV-unpossible, for few kW's it's ......
Isn't simple situation.
Best Regards.
Slava
RE: Getting power from transmision lines electromagnetic field
1. I can't see any scenario where any kind of CT can be used to provide an appreciable amount of power, evenif we disregard the system conditions issue (i.e. varying current levels in transmission line).
2. There exists a device called a Power Voltage Transformer. These are commonly used to provide station power from transmission line voltages, but are sometimes applied to supply power to villages and camps. There are commonly available up to 230 kV and 100 kVA. There are also units available at 345 kV, with ratings close to 33 kVA.
There have been projects in South America and Asia, where the rated secondary voltage of these PVTs were in the 15 kV range and small distribution networks were run from them. Since the PVTs inherently have a high impedance, regulation has to be addressed on the LV side. However, this high impedance also offers the advantage of low available fault current levels on the LV.
I've seen transmission line tap points as simple as a 230kV to 15kV PVT and an arrester installed on the side of a transmission tower. 15 kV line runs down tower and into camp and a few distribution xfmrs are placed in the camp to power the small building.
Price of a 230kV/100kVA PVT is approx. $100k.
RE: Getting power from transmision lines electromagnetic field
http://ww
RE: Getting power from transmision lines electromagnetic field
RE: Getting power from transmision lines electromagnetic field
Initially, I would like to say that things are normally done because who does did not know that they are impossible.
Gunnar, I agree with most you said:
"It will probably be possible to build an isolated platform and put a piece of conductor close to the transmission line so that varying distance would not be a problem. But the safety distance when dealing with 230 and 500 kV is such that the induction between the "primary" and "secondary" will be very small - if you do not apply system voltage insulation. And then, you could just as well use a transformer. With much better results."
I think that a "hybrid air-iron core transformer" could be used, with the iron being like a half C following the path of the magnetic field created by the lateral phase (cable) of the transmission line, with a coil wound on it. In this case, the induced voltage. It will be like a CT broken in a half but not touch the cable. Gunnar, could you do this experience, please? Thank you!
Slava, I think this discussion is more valuable than 0.00002$. Please, rise your offer!
In our region is like yours (I think), to much sun and little water. The distribution company have already tried solar (photovoltaic) technology but had no success. I do not know why. May be because they are expensive and need too much maintenance (?).
Bill, for safety, we do not like things directly connected in the transmission line phase to ground. So, capacitor dividers in remote areas are almost forbidden, as if they loose their ground connection a full voltage will be at that connection. May be in the future, with surge arresters installed along the transmission line to improve its performance, the way they think could change.
David, I think that what Bill said there is no relationship with the reactive compensation of transmission line. Also, the capacitance of these capacitor dividers is insignificantly small when compared with those of the transmission line. I agree with you when you and Gunnar say that "if it were practical it would already be used in practice". But, remember that the use of things depends on your needs. In this case we need to do something to supply small remote villages and it is important to know if this kind of device is feasible.
Again, I would like to thank all of you for discussing this matter and for playing in this forum.
RE: Getting power from transmision lines electromagnetic field
But, more often than not, it is a sad fact that things cannot be done. The very few exceptions to this are things like the flight of the bumble-bee, putting man on the Moon, making old whisky out of fresh alcohol. The success of the latter is disputed, though...
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
Best regards,
Herivelto Bronzeado
RE: Getting power from transmision lines electromagnetic field
Sort of like wind power, it isen't always there.
Maybe an approch could be a combonation of sources, and a battery set/inverter.
Not the most efficent, but it is another option.
RE: Getting power from transmision lines electromagnetic field
The distribution company installs this to fullfill a social obligation, and when their is not enough wind power it may run a device that picks up the alternating field and rectifies it, supplementing the wind turbine, with the devices located in the pylon installation.
This then takes DC at modest voltage off to nearby villages, where it supplies cheap laptop, lighting and refridgeration.
RE: Getting power from transmision lines electromagnetic field
At $100,000 that is probably the best we can do safely and practically.
divided between 100 or more users and amortized over 10 years this is much more doable than a multi-million dollar substation.
In regards to solar and wind power, they are great if you do it yourself or it is owned by a corporation with a budget for regular service.
However, sad experience with almost all types of social economic development is that giving technology to an unsophisticated group and then leaving them on their own is a waste of time and money. By the way, I have seen a successful development project. A village needed a secondary school. A small group spent months encouraging and empowering the local people. They made quiet suggestions and shared bits of information. Eventually, the villagers had the information and encouragement to form their own school.
The crowning mark of success came several years later.
One teacher resigned to take a position elsewhere. Then the other teacher left. Then the church that had supplied the rented quarters announced that the space would no longer be available. So there was a school with no classrooms and no teachers, and classes were due to start in a few weeks. The folks who had helped the villagers start the school thought that they were going to see another project fail dismally. They were heartbroken and at their wits end as to how to help. Then, suddenly, the villagers realized; If WE don't do something fast WE will lose OUR school. There was a flurry of activity, teachers were found and a classroom was found and school started on schedule.
I realize that this may seem off topic, but I lived with these people for over a year and I remember the lessons learned whenever someone suggests solar or wind power for a remote unserviced location.
Thanks all for the varied information. The next time this subject comes up, we will know what is not practical and more importantly, why it is not practical.
And the $100,000 solution will not appeal to those looking for a free lunch.
Bill
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"Why not the best?"
Jimmy Carter
RE: Getting power from transmision lines electromagnetic field
I recall Hydro Quebec once found Mcgill University to do a research on this topic. the rough ideas is to supply some spot loads along the 735kV or 500kV line without putting in step-down Trx. I don't remember all the details but they propose some kind of simple platforms under the line to gether some power from the EMF.
I don't know if they made it or not.
Sorry ca not offer more information.
QB
RE: Getting power from transmision lines electromagnetic field
Thank you for the information.
I will try to find more on this matter with Hydro Quebec and Mcgill University.
Regards,
Herivelto Bronzeado
RE: Getting power from transmision lines electromagnetic field
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
To power some microwave stations, Hydro-Quebec uses a system that relies on induced voltage on the ground wires. The system is described in the following article.
http://iee
They say in the article that they use it in around 30 locations with loads in the order of 25 kW buy it could maybe be used up to 300 kW.
LMBT
RE: Getting power from transmision lines electromagnetic field
Excelent information.
Thank you.
Regards,
Herivelto Bronzeado
RE: Getting power from transmision lines electromagnetic field
This is capacitive coupling - not inductive. Power usually goes with voltage squared - that would mean that the 1 - 2 kW mentioned in the OP would be possible also with lower voltages in the transmission lines.
I did search the IEEE site before, but wasn't able to find this very interesting article. Thanks and PLS to LMBT.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Getting power from transmision lines electromagnetic field
That's a great reference.
This is a great forum.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Getting power from transmision lines electromagnetic field
Perhaps the same scheme could be used for small varying loads by using the trapped power (constant) from the power line to maintain a stored energy system such as a battery bank.
It's an interesting problem.
old field guy
RE: Getting power from transmision lines electromagnetic field
Its been studied alot around the globe. Have you taken the time to look at these organizations that have looked at different viewpoints on providing power in rural areas.
RE: Getting power from transmision lines electromagnetic field
That is exactly what we am trying to do: "do not reinvent the wheel but look at what other countries have tried and see what works best".
This forum is for that, I think.
Best regards,
Herivelto Bronzeado