Missed this one (did I even notice Earth Day?): Ben & Jerry’s went looking for environmentally friendly ice cream technology and discovered a thermoacoustic freezer being developed at Penn State. They convinced their parent company Unilever to throw in $600,000 of financing. The researchers made excellent progress and demonstrated a device that “uses sound waves in a closed container filled with helium to create cooling.” Compression of the helium gas throws off heat and expansion refrigerates. And don’t worry about your hearing; although the tone generates 185 decibels it can’t be heard. Penn State is working with a startup on commercial development. Ben & Jerry launched a commemorative flavor, Sweet & Sonic, and a Flash demo.