Thanks to recent breakthroughs, the insides of our refrigerators could work very differently in the coming years. Scientists at GE are perfecting a method of transferring heat that uses magnets to achieve temperatures cold enough to freeze water.
The method is based off the magnetocaloric effect, which originated in the 1880s when German physicist Emil Warburg observed that certain metals have special properties in the presence of a magnetic field. In this case, metal alloys that become hot in the presence of a magnet and cold when removed are used to create a heat pump. This pump then moves heat from the colder environment of a refrigerator to a warmer environment, like your kitchen. This is similar to current refrigeration technology that uses a compressor to move heat, but using magnets could make refrigeration 20 percent more energy efficient.
In GE's prototype a thin tube of metal alloys, which allows the liquid that removes heat to pass through it, is placed inside a larger tube that holds the magnets. Depending on how the magnets are activated, they can be used to control the alloys to move the heat into or out of the refrigerator.
Magnets could make refrigeration 20 percent more energy efficient
It took teams of GE scientists from the US and Germany five years to achieve cooling of just 2 degrees Fahrenheit. Past experiments in magnetocaloric refrigeration had similar results— back in the 1980s, a team at the Los Alamos National Laboratory in New Mexico was able to achieve just a few degrees of refrigeration using expensive, superconducting magnets. GE's technology was also housed in a huge machine, but over the past decade, they've made a prototype that is the size of a moving cart. Eventually the team wants to shrink the technology even more so it can fit inside a refrigerator. They've also progressed with cooling — the teams' material scientists developed nickel-manganese alloys for magnets that function at room temperatures. This let engineers design magnets in a series of 50 cooling stages, allowing them to reduce temperatures by 80 degrees.
Since scientists are still working with a prototype, there's no word on how much a magnetocaloric refrigerator would actually cost; in the meantime, GE is talking to the US Department of Energy about turning the technology into a refrigeration standard.