Anybody who's ever taken an introductory chemistry course will be familiar with the concept of exothermic reactions, or reactions that give off energy as excess heat. Finding a way to harness this waste heat to put it to use in other reactions or applications has long been a goal of scientists around the world.
Physicists at the University of Utah may have just made a major breakthrough in discovering a possible solution to this dilemma. Orest Symko, a professor of physics, and five of his doctoral students built small devices that convert heat into sound and then into electricity, a technology whose potential for changing heat into electricity and harnessing solar energy is very alluring. To do this, Symko's students came up with new methods to improve the efficiency of acoustic heat-engine devices that transform heat into electricity. "We are converting waste heat to electricity in an efficient, simple way by using sound," said Symko. "It is a new source of renewable energy from waste heat."
The process of turning heat into electricity has two key steps: first convert heat into sound by using new heat engines collectively known as "thermoacoustic prime movers," and then turn the sound into electricity using "piezoelectric" ("piezo" = pressure or squeezing) devices that, when squeezed in response to sound waves, transform the resulting pressure into electrical current.
Fortunately, "thermoacoustic prime movers" lack moving parts so they require little maintenance and last a long time, and they have the additional advantage of not yielding noise pollution. Eventually, Symko hopes that smaller devices will convert heat to ultrasonic frequencies indiscernible to humans. "It's easy to contain the noise by putting a sound absorber around the device," he says.
The devices will first be tested within a year when they will be used to produce electricity from waste heat at a military radar facility and at the University of Utah's hot water-generating plant. Symko hopes to see them used as alternatives to photovoltaic cells within two years and as cooling devices in computers. One future goal is seeing them implemented in nuclear power plant cooling towers, where they could generate electricity from the heat released.
See also: ::Scrubbing Toxic Soil with Sound Waves, ::Capstone Micro-Turbines burn waste gas to make power and heat a greenhouse, ::Using Waste Heat From Hybrid Vehicle Battery, ::NanoLogix Patents Hydrogen Synthesis from Bacteria and Waste Heat Inputs