Ben & Jerry's Uses Sound to Chill Ice Cream

Thermoacoustic prototype that uses a "Bellows Bounce" resonator.

Penn State team behind the project, from left: Matt Poese, Dr. Steven Garrett, and Bob Smith.

Scientists have found a new way to refrigerate ice cream, by using sound waves instead of chemicals. The system, which can power a small ice-cream freezer case, is sponsored by Ben & Jerry's Ice Cream, a company known for its efforts to protect the environment.

At the heart of the system is sound -- a 190-decibel note that fluctuates some 100 times per second. That expansion and compression creates pockets of cold and warm air. A system of air circulators then funnels the cool air into the ice cream case.

The new "green" freezer isn't likely to be seen in stores any time soon, because of its cost -- considerably more than conventional freezers that use chemicals. But its creators say their system works, and it uses cheap components to do work currently done by exotic -- and often dangerous -- chemicals.

While the commercial future of the system is uncertain, it passed a recent test at a Ben & Jerry's store in New York. NPR's Robert Smith reports.