Turning heat into electricity through sound

Has been demonstrated by a team of researchers at the University of Utah. The group, led by Orest Symko, has built devices that can create electricity from the heat generated by computer chips, nuclear power plants, or even the Sun. At the June meeting of the Acoustical Society of America in Salt Lake City, five of Symko’s students reported the latest advances in their devices, which first convert heat into sound and then sound into electricity. Typically, each device is a palm-sized cylinder containing a stack of material such as plastic, metal, or fiberglass. Applying heat to one end of the stack creates a movement of air that travels down the cylindrical tube. The warm, moving air sets up a sound wave in the tube, similar to the way in which air blown into a flute creates a tone. The sound wave then strikes a piezoelectric crystal, which converts the wave’s pressure oscillations into electricity. According to Symko, a ballpark range of 10–25% of the heat typically gets converted into sound energy. The piezoelectric crystals then convert 80–90% of the sound energy into electrical energy. The team expects the devices to be used in real-world applications within two years. (ASA Meeting talks 5aPA2, 5aPA4, 5aPA5, 5aPA7, 5aPA8.)