Ice cream maker Ben & Jerry's (South Burlington, Vt.), well known for its environmental positions, has turned its attention inward. Working with scientists from Penn State University (University Park, Pa.), the company has created a freezer that uses sound waves rather than chemicals as a means of refrigeration. In the working freezer, the sound is trapped inside, keeping the 183 decibels to a hum outside the unit.

According to the company, the thermo-acoustic chiller pumps sound waves from a speaker, thereby raising and lowering pressure of helium inside. This allows it to pull heat out of the ice cream in an attached freezer. Plans call for hundreds of the devices to be in place in company stores within several years.

High-powered sound waves and helium gas are expected to keep the ice cream hard, and the technology has the potential to heat and cool homes. Any such residential aspirations are at least five to 10 years in the future, however.