After fridge magnets, the magnetic fridge

12th Feb 2009 | 21:05

After fridge magnets, the magnetic fridge

New alloy means no more chugging chillers filled with greenhouse gases

Scientists at America's National Institute of Standards and Technology (NIST) have come up with a cool new idea - the magnetic fridge.

Boffins at the Institute's Centre for Neutron Research have discovered an exotic metal alloy that enables magnetic cooling instead of the gas-compression systems currently used in refrigerators and air conditioners.

Magnetic cooling relies on materials called magnetocalorics, which heat up when exposed to a powerful magnetic field. After they radiate this heat away, the magnetic field is removed, and their temperature drops again, this time dramatically.

Absolute zero

The effect has been used for decades in the laboratory, to reach temperatures of nearly absolute zero, but has been kept out of the home because most magnetocalorics use both gadolinium (an incredibly expensive metal) and arsenic (an incredibly toxic element).

NIST's breakthrough is an alloy made of manganese, iron, phosphorus and germanium that works well at room temperature, contains no toxic arsenic and has such strong magnetocaloric properties that it could rival gas compression in efficiency.

While today's fridges don't use the ozone layer-munching CFC (chloroflurocarbon) compounds they once did, they still use HFC (hydrofluorocarbon) gases which contribute to the greenhouse effect.

The next step is getting the alloy to magnetise uniformly, after which we might soon see magnetic fridges in the shops. One word of warning: makers of fridge magnets - it could be time to start looking for a new market...

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