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Magnetic refrigeration uses the Magnetocaloric Effect and the law of [[entropy]] to produce a cooling effect. It is a new technology which has for some time been only useful in research and cryogenics. However, it is becoming a more common technology as it is quite efficient.<ref>http://www.eurekalert.org/features/doe/2001-11/dl-mrs062802.php</ref><br />Put simply, Magnetocaloric Materials heat up when exposed to magnetism. When the magnetic field is removed, they cool down again. When used for refrigeration, such a material is exposed to strong magnetism, so that it heat up, while a heat sink removes as much heat as it can. Then the material is removed from the magnetic field, but is also isolated (usually by a vacuum). The material now has a high heat capacity, and is therefore cooler than the heat sink it was just in contact with. This cold substance can now be used to cool the desired air or liquid, before the process is repeated.<ref>http://www.cooltech-applications.com/magnetic-refrigeration-principle.html</ref>