Engineers and materials scientists at the Milwaukee-based Astronautics Corporation of America recently unveiled the world's first room-temperature refrigerator that gets its chill from a permanent magnet rather than from power-hungry compressors and the ozone-depleting compounds that are still present in many kitchens. The new fridge takes the heat out using a powdered form of gadolinium, an element also used in medical MRI machines. The gadolinium is attached to a wheel that spins it in and out of a magnetic field (right), alternately magnetizing and demagnetizing the material. When the gadolinium initially magnetizes, the spins of its atoms align and give off heat. When it demagnetizes, the atomic spins return to a random distribution, cooling the gadolinium to well below its original temperature. The cold gadolinium chills a set of water pipes that extend into the refrigerator, keeping your milk from going sour and your TV dinners frozen. This process could be 50 percent more efficient than the cooling cycle used in current refrigerators. But don't go running out to the appliance store—the Astronautics Corporation says the magnet-o-fridge will not be available to consumers for another five to eight years.
Photograph courtesy of Astronautics Corporation of America
