Thanks to recent advances, our refrigerators may work quite differently within a few years. Scientists at GE (General Electric) are refining a method of heat transfer that uses magnets to reach temperatures low enough to freeze water.
The method rests on the magnetocaloric effect, which goes back to 1880, when the German physicist Emil Warburg noticed that some metals have particular properties in the presence of a magnetic field. Metal alloys that heat up in the presence of a magnet and cool down when it is taken away are used to build a heat pump. The pump moves heat out of the colder interior of the refrigerator into a warm room such as your kitchen. This is similar to present-day cooling technology, which uses a refrigeration compressor to move heat, but with magnets it is possible to build a refrigerator whose energy consumption is 20 per cent lower.
The GE prototype is a thin tube of metal alloys containing a liquid that carries the heat away. It sits inside a larger tube that holds the magnets. Depending on how the magnets are activated, they can be used to control the movement of heat into or out of the refrigerator.
The prototype the scientists built is the size of a cart. In the end the team wants to shrink it further, so that it will fit inside a refrigerator. They have also made progress with the cooling itself: they have developed nickel-manganese alloys for the magnets that work at room temperature.
Since the scientists are still working with a prototype, there is unfortunately no word on what a magnetocaloric refrigerator will cost.