Magnetic refrigeration is a cooling technology presently (2003) being developed by a partnership of the United States Department of Energy's Ames Laboratory and Astronautics Corp. of America. A proof-of-principle model was successfully demonstrated in 1996.

The technology uses the magnetocaloric effect, which is the tendency of certain materials, such as the metallic element gadolinium, to heat up when placed in a magnetic field and to cool down when removed from the field.

Source

Ames Laboratory news release of May 25, 1999 at http://www.ameslab.gov/News/release/crada.html.