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Q & A: alternative magnetic energy?

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Most recent answer: 12/27/2014
Q:
How are magnets being used as an alternative energy?
- Helen
MI
A:
Magnets are plenty useful in conventional energy conversion systems. They’re essential in the generators which convert chemical or nuclear energy to electrical forms via mechanical forms, and in the motors which convert that back to mechanical energy.

As for the ’alternative’ uses, in which the magnets are supposed to be sources of limitless energy themselves, they’re fakes, pure and simple. They violate fundamental physical laws, so it’s not surprising that they never actually work when tested by someone who isn’t selling stock in some bogus company.

Mike W

(published on 10/22/2007)

Follow-Up #1: alternative magnet energy

Q:
But I heard that magnets are a reliable alternative energy source from many knowlegable sources.
- Anonymous
OR
A:
You might try asking those ’reliable sources’ to show you a single working model. And remember, it better not have hidden batteries or wires.

p.s. Did they tell you it’s a ’slam-dunk’?

Mike W.

Lee H

(published on 10/22/2007)

Follow-Up #2: magnetic energy?

Q:
I don't know how much sense this makes, but, with the aid of the earth's magnetic field, couldn't we make super magnets? And, if so, wouldn't it be an alternative magnetic energy source? Law of conservation has destroyed all of my other energy ideas. Right now I'm working on a bike. =) http://www.instructables.com/id/Turn-an-exercise-bike-into-an-energy-bike/?ALLSTEPS
- Stephen Lupton (age 15)
US!!!
A:
I'm not sure what you mean by 'super magnets'. The Earth's field isn't of much use in making strong magnets of any type, since it's thousands of times weaker than field you can easily make with ordinary lab electromagnets.
Yeah, the conservation of energy (First Law of Thermodynamics) does put a crimp in a lot of schemes. So does the Second Law.
The idea of actually using the substantial work exerted on an exercise bike to charge some batteries sounds great.

Mike W.

(published on 05/16/2013)

Follow-Up #3: zero-point energy

Q:
This is more than likely absurd, but I heard that the symmetry breaking that produced the universe should have had much more energy released in the process...The line of reasoning being that the energy density of free space is therefore quite large and that by cleverly creating an open system, it could be possible to extract zero point energy...These guys (Moray B. King) were looking at concepts like noise from diodes, all the way up to balls of plasma. Is there anything to this at all? If you were to create some sort of self sustaining dynamo action, could it be checked for anomalous energy?
- Deon (age 23)
Lansing
A:
We do not know whether the vacuum is in its lowest possible energy state. It is possible that it isn't, which is one way of accounting for the dark energy driving accelerating expansion of the universe. Perhaps in some far distant future it will switch to an entirely different state via a phase transition, essentially wiping out whatever was there beforehand. That may have happened once already in an early inflationary era.

And no, the claims that fooling around with plasma balls or diodes will access this hypothetical energy source have absolutely nothing to support them. No experimental evidence, no actual theoretical arguments, nothing.

Mike W.

(published on 10/21/2009)

Follow-Up #4: energy from magnets?

Q:
I understand that magnets cannot be used as a limitless source of energy, but is it possible then for them to be used as long-lasting sources of energy. The like does not exist yet, but perhaps some system can be used to make use of this source of energy that lasts a long time?
- Thomas (age 15)
Melbourne, FL, U.S.A.
A:

There's very little energy stored in that magnetization. A good permanent magnet has some field energy that could be lowered by losing its permanent magnetization. Very roughly, that energy is around 0.1J/cm3 times the magnet volume. So taking a big magnet (say 1000 cm3 volume) one might be able to extract about 100 J from it. You could light a nice bright high-efficiency LED bulb for about 10 seconds with that energy.

What magnets are good for is not as an energy source but as part of devices to convert mechanical energy to electrical and vice versa- generators and motors. Wind turbines, for example, use particularly strong special magnets in their generators. The energy comes from the wind.

Mike W.


(published on 11/10/2013)

Follow-Up #5: What is magnetic field energy?

Q:
When you say energy stored in magnetization, do you mean the energy gained from the domains? I don't understand what is meant by field energy, please do explain.
- Holvets (age 24)
Seattle
A:

There are a couple of ways of thinking of this. Classical fields (electric, magnetic, gravity) describe forces between objects. The potential energy changes as the objects get closer or farther, with the rate of change just being the force. In each case you can mathematically show that the potential energy can be written as an integral over space of the square of the field.  Likewise the energy change that happens when two domains change the relative alignment of their magnetizations can be described as a dipole-dipole interaction between two magnets or equivalently as a change in that field energy. When the fields are propagating, as with electromagnetic waves, the same field energy description accurately gives the energy flow. So it makes sense to say that the field itself is where the energy is located. 

Quantum mechanically, everything consists entirely of fields, including things we often picture as classical particles, so if energy is to mean anything there had better be a way of describing it as field energy.

Mike W.


(published on 12/03/2013)

Follow-Up #6: magnetization energy

Q:
Wait, bear with me here... How is it possible to get energy by dissipating magnet's? A magnet has a energy density of 100 J/cm^3. It's domains are mostly aligned. By causing those domain's to lose their alignment (demagnetization) there is energy gained in the form of heat = 100J? I'm confused. Because there are multiple energy terms in magnetization. The energy density in the field should = the magnetization? This is based of my understanding from what you said earlier.
- Holvets (age 24)
Seattle
A:

The energy density in the field is not the same as the magnetization. One way to see that is that energy density is a scalar number but the magnetization is a vector, pointing some direction. The energy density is proportional to the square of the magnetic field, in empty space. If you have two little domains they can lower the energy by lining their fields up in the same direction along the line from one domain to the other. Another way to lower the energy is to line up opposite directions at right angles to the line between the domains. For a little needle, the lowest energy state can be just a single domain lined up along the needle direction. For wider samples, energy can be lowered by breaking into stripe-like domains next to each other, pointing opposite ways, or into more complicated patterns. That leaves very little net magnetization.

Mike W.


(published on 12/03/2013)

Follow-Up #7: getting energy from magnets

Q:
When people ask about the energy stored in a magnet, I suggest a thought experiment. Hold a strong horseshoe magnet above a piece of iron on the table. If they're close enough, the magnet will lift the iron off the table and stick to the magnet. By lifting the iron off the table against gravity, the magnet has literally done work on the piece of iron. Where did that energy come from? From the magnetic field in the magnet. But isn't the magnet still magnetized? Yes, but it can be shown that the field now contains less energy than before because of the iron stuck to the poles. This loss of energy is exactly equal to the work the magnet did in lifting the iron. Now pull the iron and magnet apart. You had to apply force, right? You did that over a distance, which means you did work on the iron/magnet system. Where did that work go? Back into the magnetic field of the magnet. So while it is possible to get energy out of a magnet, it's not free. You have to put it back or you can't get it again. It's much like letting a rock fall. Energy is released, but once the rock hits the ground that energy is gone. To get it back you have to lift the rock back to its starting point. There's no free lunch!
- Phil (age 57)
San Diego, CA
A:

That's a nice clear explanation.

Mike W.


(published on 01/10/2014)

Follow-Up #8: can mechanical devices amplify energy?

Q:
I can understand and see the beauty and simplicity of the principle of energy conservation. But, since I am only an enthusiastic about the subject I still have some difficulty in perceiving the impossibility of something similar to an “ideal generator” such as those being fallaciously claimed throughout the internet. Two of the “six simple machines”, the lever and the pulley, give me the impression of some sort of mechanical energy amplification, in the sense that you can use these machines to lift something very heavy applying very little force. A very simple description of the functionality of the lever states that “A lever amplifies an input force to provide a greater output force, which is said to provide leverage.” In parallel to the principle behind these machines, isn’t it possible to make a generator that, by the use of clever mechanisms transforms a small input of energy into a bigger output? Being the inputs provided by mechanical or electrical sources and the output an electrical one. I also wonder about this when I see the common park swing, that you may use very little force to make even a adult swing back and forth very rapidly, and that a simple adaptive generator could be inserted to the base of the swing and transform the movement into a bit of electrical energy… how much, I don´t know, but I can´t stop to believe that it is lesser than the force being dispended by the swinger, whom with a simple movement of the legs contrary to the motion can even accelerate the speed up to a loop around the horizontal rod of the swing. What seems to explain the amazing quantity of videos on youtube claiming these ‘magnetic free energy generators’ is the potentiality of magnets generating such an amplifying movement. So, in short my question is: can a mechanical device amplify an input of energy into a greater output, without violating the principle of energy conservation? Please notice that this is, at least in my mind, very distinguished of the so called “perpetual motion” concept… what I wonder is a machine such as the lever, but that provides an electrical energy output. I have high hopes of having some answer. But I appreciate the service you provide and understand that my question is a little bit of the main subject here, and completely of the text format. So I thank you beforehand if got to read it all up to here! Happy New Year!!!Remember...we don't answer homework questions!
- Rodrigo Abreu (age 22)
Rio de Janeiro, RJ - Brazil
A:

This is a very important question. Mechanical devices cannot amplify energy inputs. 

The lever that amplifies the force applied will move an object a shorter distance than the distance moved by the whatever applies the force. As a result the work done on the object moved (i.e. the energy transferred to it) is at best equal to the energy supplied by the force applied. (There can be a bit of energy lost to heat due to friction at the fulcrum.)

The same principle holds for all devices, mechanical and electrical. Certainly it applies to the work you do pumping your legs to get a swing to swing higher. The chemical energy you burn up partly goes to the swing motion+gravitational potential and partly goes to just heating up your muscles.

Mike W.


(published on 12/27/2014)

Follow-up on this answer.