Magnets: Alternative Power Sources

Magnets can be used to generate small amounts of electricity.

Magnets are used all over the house, from holding successful school papers and tests on the refrigerator to speakers in our stereos. They can also be a source of light-duty power generation when they are spun on a rotor near wire coils on a stator, since the changing magnetic field will induce a current in the wires.

Faraday's Law

A basic tenet of electrical and magnetic physics is Faraday's Law, which states that when a coil rests in a changing magnetic field, a level of voltage will be induced in the coil. This can occur in one of two ways: the magnetic field itself can be changed, or the coils themselves can have their orientations changed. The rate of change of the magnetic field, called the change in magnetic flux, will determine how much electricity is generated, as will the number of turns in the coil and the area of the coil.

Homemade Alternator

You can build a large-scale alternator at home by mounting a series of strong bar magnets on a wooden wheel and building a base in which the wheel spins. There should be just as many coils as there are magnets, and they should come as close as possible without touching. The coils can be connected together in series or in parallel, and when the wheel is spun, the output of the coils will be a sinusoidal wave of current known as an alternating current. You can build a handle into the wheel's axle to be spun by hand, or you can attach the axle to a drill which will give you a steadier current.

Large Scale Power

While a hand-cranked alternator can be a fun science project, huge industrial-strength magnets are being used in developing a sustainable power generation system by providing a magnetic field for fusion reactions to take place in. In 2002, a team of scientists from the Massachusetts Institute of Technology developed a 150-ton magnet that will eventually be part of a 925-ton assembly of magnets that will be used to confine and control the plasma in which hydrogen atoms will fuse with each other to form helium, expelling massive amounts of energy in the process.

Limitations

Magnets are not yet used in commercial power systems because the cost of development is too high. Because of the uncertainty in this new technology, developers are building large magnets with a large margin of error so that the magnets and conductors are not brought to their theoretical limits. This results in unnecessary expenditures. Electrical losses are also high initially, though they do tend to level out as time goes on. The magnet developed by MIT researchers only stores about 640 megajoules of power, according to Sciencedaily.com, which equates to 0.178 megawatt-hours, which is significantly less power than a coal-fired or nuclear power plant produces.

References

• Georgia State University: Faraday's Law
• Science Daily: 150-Ton Magnet Pulls World Toward New Energy Source