Shinya Hasegawa and colleagues at Tokai University have developed a refrigerator (107 C) powered only by waste heat that generated sound waves in an innovative multistage traveling wave thermoacoustic engine. The refrigerator produced the gas oscillations and refrigeration at a temperature lower than the boiling point of water and achieved a minimum cold temperature of -107.4 C when the hot temperature was 270 C. The findings are published in the journal of Applied Thermal Engineering, November 2016.