MIT School of Engineering | Why can’t magnetism be used as a source of energy?


Why can’t magnetism be used as a source of energy?

Because magnets don’t contain energy — but they can help control it…

By Sarah Jensen

In 1841, German physician and physicist Julius von Mayer invented what would become the first law of thermodynamics: “Energy can neither be created nor destroyed,” he wrote. This can, however, to be converted from one type to another – by solar panels that turn sunlight into electricity, or in the transformation of natural gas molecules into heat that cooks our dinner and heats our homes.

“Magnetism is a force, but it has no energy of its own,” says David Cohen-Tanugi, vice president of the MIT Energy Club and John S. Hennessy Fellow in MIT’s Materials Science and Engineering Department. Yet, he adds, “magnetism is extremely useful in converting energy from one form to another. About 99% of electricity generated from fossil fuels, nuclear and hydroelectric power, and wind comes from systems that use magnetism in the conversion process.

All power generation technologies – except photovoltaics – rely on spinning turbines that set electrons in motion and push them through circuits and generators. “As these charged particles pass the magnets inside the turbines, they create a field around them that affects other charged particles,” Cohen-Tanugi explains. “It is the magnetic force that converts energy from wind, coal and nuclear fuel into electricity that is sent into the power grid.”

Much of this network is also managed using the principles of magnetism. “The transformer stations you see along the highway or in industrial areas are responsible for converting high-voltage electricity to usable 110 volts,” Cohen-Tanugi says. High-voltage lines deliver power from the power station to transformer stations, and as electrons move through the large transformer coils, they generate magnetic fields that change the frequency of electricity to a safe voltage to power our toasters, bedside lamps and hair dryers. .

Generators and motors in everything from hybrid cars to computer hard drives use magnets, and researchers are currently investigating the potential of rare-earth magnets, exceptionally strong permanent magnets made from alloys of rare-earth elements. . Already used in advanced motors and generators and other applications in the energy sector, they represent the next generation of magnetism’s role in power generation.

Thanks to Mark Taylor, 51, of Charlotte, NC, for this question.

Posted: May 22, 2012


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