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 magneto-calorific 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.