National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”
Question
Asked 29 January 2016
We are using magnetic Generators, Why can't we use electro static generators to produce Electric power?
coil wound alternators are used everywhere to Generate electric power in all kind generating stations.Though it is demonstrated by vande graf (static generator) it is is not popular in power generation. Let me know the limitations and constraints if any
Most recent answer
David Gibson I thought a bit about it, and reframed it in terms of force in Newtons. I am fleshing out an introduction, and appreciate critical feedback.
If approached in terms of Force in Newtons, the difference becomes more practical and comparable in terms of units. For example:
F=qE
Force (in Newtons) equals the electric charge of the particle (Mg +2), times the elementary charge, times the magnitude of the electric field E (525,000 V/m like in later experiments). If we consider the force output of our single magnesium ion when subjected to the electric field, we get:
e = 1.602 10-19 C
q = 2e = (2(1.602 10-19 C)
= 3.204 10-19
E = 525,000 V/m (5,250 volts at 1 cm gap for illustration)
So total Force equals:
F = (3.204 10-19 C)(525,000 V/m)
F = (1.682110-13 N)
Since a Newton is the force of 1 kilogram per meter, per second squared, one can easily calculate and visualize this force.
For magnetic fields, the force is also equal to the charge of the particle, times the elementary charge, times the velocity of the particle, times the magnetic field magnitude.
F=qvB
Clearly, when the particle is not moving, there is zero force on our magnesium ion. If we take into consideration the velocity of magnesium ions at a practical velocity of 1 meter per second, we again end up with:
e = 1.602 10-19 C
q = 2e = (2(1.602 10-19 C)
= 3.204 10-19C
Keeping in mind that
E=cB
Where:
c = (speed of light 3.00x10^8 m/s)
So that B = E/c
For our instance: (525,000) V/m(3.00 108) m/s
B = 0.00175 Vs/m^2 (Volt per second, per meter squared, or Teslas T)
We will express the magnetic field in this format for comparison and returning back to our Magnesium ion, we end up with:
c = (speed of light 3.00x10^8 m/s)
F = (3.204 10-19 C)(1 m/s)(0.00175 Vs/m^2)
F = (5.60710-22 N)
Comparing the two forces:
F = (1.682110-13 N) for the electric field.
F = (5.60710-22 N) for the magnetic field.
There is an obvious disparity, which comes as no surprise. It is also clear that the velocity of our magnesium ion must increase to the unattainable and impractical speed of light in order to reach the same force when using magnetic fields compared to electric fields. While hardly novel or revolutionary on its own, it is perhaps useful as a figure of merit to ask why haven't electric fields been more rigorously pursued as a field of study and for applications? In fact, some might say it is redundant and remedial at best, though again it could be asked why there has been such a gap in research? If the reader of this thesis walks away with the idea that the electric field should in fact be more researched, with practical applications developed, it will be considered a contribution to scientific knowledge in the mind of the author.
When considering historical investment in various topics of research, it becomes apparent that there are many factors that have little to do with scientific discovery, and more to do with inertia and the considerations of the day. Magnetic generators are efficient, safe, and reliable which is why it comes as no surprise are the foundation of the electrical grid, power generation, and radio systems we use today. However, with the improvement of materials science, and a more thorough understanding of what is possible with electric fields, there are good reasons to look back again into the somewhat improperly named field of “electrostatics”.
If anyone here has any feedback, positive or critical, it is welcome.
Popular answers (1)
University of Exeter
Some of the answers posted here so far have, I think, rather missed the point; but then, so did the question. The salient point is that the 'opposite' of 'magnetic' is not 'electrostatic' but simply 'electric'. Forget the term 'electrostatic', as that is just misleading. Conventional so-called electrostatic generators are designed to generate high voltages (for 'static electricity') rather than power. If we want to generate power then we simply look to the electric analogue of a magnetic power generator. As I will demonstrate, electric machines are theoretically much better at generating power than magnetic machines; but there are good reasons why they have not caught on.
Consider, first, how a generator works using magnetic induction. A moving magnet (relatively speaking) causes a time-varying magnetic field which generates a voltage in a loop of wire. If you complete the circuit to allow a current to flow, you dissipate energy and this arises because of the energy required to move the magnet against the field induced in the loop. A magnet is manufactured by allowing a material to 'solidify' in an area of high magnetic flux, so that the magnetic domains are 'frozen' in place.
A magnet is, more formally, a ferromagnetic material. Now consider the electric equivalent of a magnet, which is a ferroelectric material, also known as an electret.
A moving electret causes a time-varying electric field which generates a current in a wire/plate. If you complete the circuit to allow a potential to build up, you dissipate energy and this arises because of the energy required to move the electret against the field induced in the wire/plate. An electret is manufactured by allowing a material to 'solidify' in an area of high electric flux, so that the electric domains are 'frozen' in place.
The analogy is interesting, yes?!
Although 'magnetic induction' is the more familiar phenomenon, you will probably have done physics experiments at school with 'electric induction' using an electrophorus, which is a device for transferring electric charge from a reservoir. One of the key points in those physics lessons was to get the pupil to explain why it apparently allows you to transfer charge indefinitely, i.e. where does all the charge come from? That’s a very clever question, and it baffles most students, but it is only like asking why a magnet lasts 'for ever'.
Now, the energy storage density of a magnet is simply ½ B.H which, for a NdFeB magnet with a relative permeability of about 1 and a saturation flux density of (say) 1.3 T [Tesla, equal to As/m^2], gives about 0.8 MJ/m^3. The energy storage density of an electret is, similarly, ½ D.E which, for barium titanate, with a relative permittivity of about 200 and a saturation flux density of 0.16 Vs/m^2 [that unit has no common name, unlike the magnetic analogy], gives about 7 MJ/m^3. The energy storage is not, in itself, directly relevant but it is useful as a figure of merit to describe the material and its potential (excuse the pun) as a generator of power.
So you can see that an electric generator could be ten times better than a magnetic generator for the same volume of active material. So why do we not use electric generators?
Well, of course, they are used. For very small devices (not necessarily "nano" but just "micro" or "milli" devices) they can work better than a magnetic generator because they do not require a bulky copper coil to be added to the assembly.
However, for larger devices there are a number of engineering reasons why they are not used. To achieve the theoretical maximum flux density in an electret requires a high electric field strength and, due to the breakdown voltage of the material, this may limit it to a thickness of perhaps 1mm - so large devices are not practical. There are several other reasons, including those of cost, and of 'historical investment' by which I mean that there is a large body of knowledge on magnetic generators and no real incentive to find an alternative – except for specialised and very small devices. But, if there ever were a need for such generators, one can assume that suitable ferroelectric materials will swiftly find their way into the marketplace.
Hope this helps!
5 Recommendations
All Answers (12)
University of Nottingham
Static electricity is usually high voltage and low current, the product being power.
Current static generators, Wimshurst machine Van de Graf etc. Only produce very low power levels, even in big machines, although voltages can me in the Mega-volt region.
Even lighting strikes, (i.e. a machine comparable to the size of the earth) where current can be in the 100,000 amp region at mega-volts, hence produce large amounts of power are not useful as the strikes are very short, in the nanosecond region, so the energy content is low. (power x time = energy)
Static generating machines are also very inefficient in terms of work in, to power out.
Magnetic generators are only limited by their size, and efficiency can be close to 100% if designed correctly.
Basically, magnetic devices are more power dense than electrostatic ones. Certainly at larger sizes. (i.e. things humans can see)
At nano size, electro-static forces tend to dominate, so static force and generation is sometimes more appropriate.
Best Regards
Paul
2 Recommendations
Dr. Ambedkar Institute of Technology
You are absolutely correct sir. But in exponentially growing demand for electricity , can we adopt small scale static generators to illuminate our houses fitted with LED bulbs?This is my concern sir.
with Regards
vasanth
University of Nottingham
There are inventions that do what you ask for example:
Also there is much interest in energy harvesting for low power devices:
Where mains or battery energy sources are not available.
A question you ask yourself is "why use a large and inefficient static generator, when a magnetically based one is smaller, cheaper and requires less input energy?"
Please mark up answers you find useful.
Best Regards
Paul
2 Recommendations
Dr. Ambedkar Institute of Technology
well, i have gone through the links you suggested,and they are really useful to a greater extent.Thank you sir
with best regards
vasanth
1 Recommendation
Dear G.s. Vasantha Kumar,
According to your application, LEDs like small power consuming applications could minimize the large amount of power it still keep arising the question about applicability and public acceptances. Power industries are still getting stuck on supporting the bulk power consumer. Thats why they are concentrating on SG or large power generation sources. In your case, It must has huge prospects to society but huge a big branch of further study to meet the demand and production of this.
University of Technology of Belfort-Montbéliard
In nanotechnology, there are electrostatic generator !
It is limited as a generator in the power stations seen their performance
University of Exeter
Some of the answers posted here so far have, I think, rather missed the point; but then, so did the question. The salient point is that the 'opposite' of 'magnetic' is not 'electrostatic' but simply 'electric'. Forget the term 'electrostatic', as that is just misleading. Conventional so-called electrostatic generators are designed to generate high voltages (for 'static electricity') rather than power. If we want to generate power then we simply look to the electric analogue of a magnetic power generator. As I will demonstrate, electric machines are theoretically much better at generating power than magnetic machines; but there are good reasons why they have not caught on.
Consider, first, how a generator works using magnetic induction. A moving magnet (relatively speaking) causes a time-varying magnetic field which generates a voltage in a loop of wire. If you complete the circuit to allow a current to flow, you dissipate energy and this arises because of the energy required to move the magnet against the field induced in the loop. A magnet is manufactured by allowing a material to 'solidify' in an area of high magnetic flux, so that the magnetic domains are 'frozen' in place.
A magnet is, more formally, a ferromagnetic material. Now consider the electric equivalent of a magnet, which is a ferroelectric material, also known as an electret.
A moving electret causes a time-varying electric field which generates a current in a wire/plate. If you complete the circuit to allow a potential to build up, you dissipate energy and this arises because of the energy required to move the electret against the field induced in the wire/plate. An electret is manufactured by allowing a material to 'solidify' in an area of high electric flux, so that the electric domains are 'frozen' in place.
The analogy is interesting, yes?!
Although 'magnetic induction' is the more familiar phenomenon, you will probably have done physics experiments at school with 'electric induction' using an electrophorus, which is a device for transferring electric charge from a reservoir. One of the key points in those physics lessons was to get the pupil to explain why it apparently allows you to transfer charge indefinitely, i.e. where does all the charge come from? That’s a very clever question, and it baffles most students, but it is only like asking why a magnet lasts 'for ever'.
Now, the energy storage density of a magnet is simply ½ B.H which, for a NdFeB magnet with a relative permeability of about 1 and a saturation flux density of (say) 1.3 T [Tesla, equal to As/m^2], gives about 0.8 MJ/m^3. The energy storage density of an electret is, similarly, ½ D.E which, for barium titanate, with a relative permittivity of about 200 and a saturation flux density of 0.16 Vs/m^2 [that unit has no common name, unlike the magnetic analogy], gives about 7 MJ/m^3. The energy storage is not, in itself, directly relevant but it is useful as a figure of merit to describe the material and its potential (excuse the pun) as a generator of power.
So you can see that an electric generator could be ten times better than a magnetic generator for the same volume of active material. So why do we not use electric generators?
Well, of course, they are used. For very small devices (not necessarily "nano" but just "micro" or "milli" devices) they can work better than a magnetic generator because they do not require a bulky copper coil to be added to the assembly.
However, for larger devices there are a number of engineering reasons why they are not used. To achieve the theoretical maximum flux density in an electret requires a high electric field strength and, due to the breakdown voltage of the material, this may limit it to a thickness of perhaps 1mm - so large devices are not practical. There are several other reasons, including those of cost, and of 'historical investment' by which I mean that there is a large body of knowledge on magnetic generators and no real incentive to find an alternative – except for specialised and very small devices. But, if there ever were a need for such generators, one can assume that suitable ferroelectric materials will swiftly find their way into the marketplace.
Hope this helps!
5 Recommendations
Dr. Ambedkar Institute of Technology
Dear David Gibson
That is an excellent in depth answer with mathematical calculation.Your answer definitely gives insight in to the practical limitations of the process.Thank you very much for sharing your knowledge here.
with regards
vasanth
National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”
Dear Dr. David Gibson,
Thank you for your answer and explanation! It is one of those I return to from time to time and it lead to my interest in electric fields. I also considered the magnitude of an electric field compared to magnetic, and when you derive from Maxwell´s Equations that E=cB it became obvious that the electric field magnitude is equal to the magnetic field magnitude, times the speed of light 3.00 x 10^8 m/s. I thought about this a lot, and reworked the calculations to review and get a better idea. Indeed, when you consider how much greater the magnitude of an electric field, it begs the question why they are not a more intense subject of study. Additionally, electric fields can have a source and a sink, while magnetic fields do not. Non-uniform electric fields and their effects on liquids with a permanent dipole (e.g. water, methanol), and for use in ion migration in a fluid, as well as even generators for solid state flight applications is an almost untapped field of inquiry which should be developed. David Gibson
University of Exeter
Im glad you found my notes helpful. Unfortunately you are very much mistaken in saying that the electric field has a greater magnitude than the magnetic field. The fields cannot be directly compared as they are different things and are measured in different units. Its like saying that metres are bigger than kilograms! It really doesnt make sense!
The reason the *numeric* values of the fields might leads you to suppose one was greater than the other is only because of the units we have artificially defined to measure them. The standard SI units are only one way of measuring the fields. If you use a different system of units the comparison will be different. Suppose that instead of the metre, we use a unit of distance equal to the parsec to define our measurements (The parsec is a very large distance). That would not change any field magnitude except in *purely* numeric terms - the fields themselves would be unaltered.
1 Recommendation
National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”
David Gibson Thank you for your reply Professor, and walking me through my thoughts on this. Yes, the units are different, but can they not be converted to something for an illustration? For example, looking at the force equations for electric and magnetic fields:
F=qE for the force in Newtons from an electric field on a particle of a given charge (let´s say Magnesium so +2 elementary charge).
F=qvB for the force from a magnetic field on a particle of a given charge, times the speed of light "v". From this point, we can consider the force output in the same terms. Is it not a helpful illustration, or should I be considering something else?
National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”
David Gibson I thought a bit about it, and reframed it in terms of force in Newtons. I am fleshing out an introduction, and appreciate critical feedback.
If approached in terms of Force in Newtons, the difference becomes more practical and comparable in terms of units. For example:
F=qE
Force (in Newtons) equals the electric charge of the particle (Mg +2), times the elementary charge, times the magnitude of the electric field E (525,000 V/m like in later experiments). If we consider the force output of our single magnesium ion when subjected to the electric field, we get:
e = 1.602 10-19 C
q = 2e = (2(1.602 10-19 C)
= 3.204 10-19
E = 525,000 V/m (5,250 volts at 1 cm gap for illustration)
So total Force equals:
F = (3.204 10-19 C)(525,000 V/m)
F = (1.682110-13 N)
Since a Newton is the force of 1 kilogram per meter, per second squared, one can easily calculate and visualize this force.
For magnetic fields, the force is also equal to the charge of the particle, times the elementary charge, times the velocity of the particle, times the magnetic field magnitude.
F=qvB
Clearly, when the particle is not moving, there is zero force on our magnesium ion. If we take into consideration the velocity of magnesium ions at a practical velocity of 1 meter per second, we again end up with:
e = 1.602 10-19 C
q = 2e = (2(1.602 10-19 C)
= 3.204 10-19C
Keeping in mind that
E=cB
Where:
c = (speed of light 3.00x10^8 m/s)
So that B = E/c
For our instance: (525,000) V/m(3.00 108) m/s
B = 0.00175 Vs/m^2 (Volt per second, per meter squared, or Teslas T)
We will express the magnetic field in this format for comparison and returning back to our Magnesium ion, we end up with:
c = (speed of light 3.00x10^8 m/s)
F = (3.204 10-19 C)(1 m/s)(0.00175 Vs/m^2)
F = (5.60710-22 N)
Comparing the two forces:
F = (1.682110-13 N) for the electric field.
F = (5.60710-22 N) for the magnetic field.
There is an obvious disparity, which comes as no surprise. It is also clear that the velocity of our magnesium ion must increase to the unattainable and impractical speed of light in order to reach the same force when using magnetic fields compared to electric fields. While hardly novel or revolutionary on its own, it is perhaps useful as a figure of merit to ask why haven't electric fields been more rigorously pursued as a field of study and for applications? In fact, some might say it is redundant and remedial at best, though again it could be asked why there has been such a gap in research? If the reader of this thesis walks away with the idea that the electric field should in fact be more researched, with practical applications developed, it will be considered a contribution to scientific knowledge in the mind of the author.
When considering historical investment in various topics of research, it becomes apparent that there are many factors that have little to do with scientific discovery, and more to do with inertia and the considerations of the day. Magnetic generators are efficient, safe, and reliable which is why it comes as no surprise are the foundation of the electrical grid, power generation, and radio systems we use today. However, with the improvement of materials science, and a more thorough understanding of what is possible with electric fields, there are good reasons to look back again into the somewhat improperly named field of “electrostatics”.
If anyone here has any feedback, positive or critical, it is welcome.
Similar questions and discussions
AI-Driven Approach to Identifying the Ideal Time-Frame to Contact Professors for Funded Positions and Research Collaborations ( Data Thread)
Tasfia Noor Chowdhury
AI-Driven Approach to Identifying the Ideal Time-Frame to Contact Professors for Funded Positions and Research Collaborations ( Data Thread)
I know this topic might sound silly at first, but if you're applying abroad and looking for scholarships, it’s not obscure at all. For many students, getting a reply from the professors they aspire to work with is a dream come true!
I believe that problems lead to solutions, and I genuinely want to dive deep into this topic and extract meaningful insights.
Of course, there are some challenges to consider:
- The Big Dataset! I believe students who are reaching out to professors can help contribute to this research. Here’s a Google Sheet: https://shorturl.at/5kQEM where you can share your data—it’s not a Google Form because people tend to skip those! It’ll take less than a minute to share your info with us.
- Time Zone Considerations: The second column in our dataset is the country, but if we can make equivalent assumptions based on daytime hours, this shouldn’t be an issue. What’s your take on this?
- Collecting Data from Professors: While this isn’t a groundbreaking problem to solve, it matters a lot to students. If any professor is willing to share their schedule or thoughts on this topic, we would wholeheartedly welcome their input. Sheet 2 if for respected Professors - https://shorturl.at/5kQEM
Thank you so much for reading this far! Cheers!! 🚀
CFP: 2025 International Conference on Renewable Energy and Energy Conservation (REEC 2025)-January
Chuliang Wu
2025 International Conference on Renewable Energy and Energy Conservation (REEC 2025) will be held in-person on January 10-12, 2025 in Xinyu, Jiangxi, China.
Conference Website: https://ais.cn/u/2mMjEb
---Call For Papers---
The topics of interest for submission include, but are not limited to:
◕ Renewable Energy
· Renewable Energy Engineering(Solar, Biomass, Wind, Nuclear, Hydrogen, etc.)
· Renewable Energy Power Generation
· Renewable Energy Power System Modeling, Analysis and Simulation
· High Reliability Relay Protection Technology for Renewable Energy Power Systems
◕ Energy Technology, Utilization and Development
· Energy Saving and Environmental Protection Technology
· Sustainable Coal Utilization and Clean Coal Technology
· Natural Gas Hydrate Development Technology
· Clean Production and Green Chemical Technology
· Energy Internet Technology
· Energy Efficiency
· Hydrogen and Fuel Cells
· Energy Clean Utilization
◕ Electricity, Electrical Systems
· Electric Motors and Drives
· Power Converter
· Electric Battery and BMS
· Smart Grid Power Transmission and Distribution
· Noise, Vibration, EMI and EMC
· Power Quality
· Power System Analysis
· New Power System Technologies
· Power Systems and it's Automation
· MEMS-Microsensors and Structures
· Sensors and Micro Machines
......
---Publication---
All papers submitted to REEC 2025 will be reviewed by two or three expert reviewers from the conference committees. After a careful reviewing process, all accepted papers will be published in the Conference Proceedings, and submitted to EI Compendex, Scopus and Inspec for indexing.
---Important Dates---
Full Paper Submission Date: December 30, 2024
Notification Date: January 10, 2024
Final Paper Submission Date: January 03, 2024
Conference Dates: January 10-12, 2025
--- Paper Submission---
Please send the full paper(word+pdf) to Submission System:
Recommendations
Soft automatic load reconfiguration enables best operation of limited power, power systems. In agent based systems, the negotiation between loads can be based on absolute indexes, such as priority levels, or on the actual state of the system at the negotiation time. In this work an experiment is performed using power quality indexes, computed on-li...
Multi-input PSS (P+ω+Q type PSS) using the three input
signals (P, ω, Q) which it is more excellent than the conventional
PSS is developed. In this paper, the design method of multi-input PSS
which uses the high speed genetic algorithm (HSGA) is proposed. This
method realizes the highly-efficient design of parameters of multi-input
PSS. The high st...
Nathan Cohn's newly proposed technique of coordinated, system-wide correction of time error and inadvertent interchange is examined and validated by computer simulations. Area and system performances are investigated for a sudden change in load or generation in a three-area power system. The following effects are examined: changing the time of corr...