New Way of Coverting the Heat of your Laptop into Electricity

University of Utah physicists developed small devices that turn heat into sound and then into electricity. The technology holds promise for changing waste heat into electricity, harnessing solar energy and cooling computers including the laptops and radars.

University of Utah physicist Orest Symko demonstrates how heat can be converted into sound by using a blowtorch to heat a metallic screen inside a plastic tube, which then produces a loud tone, similar to when air is blown into a flute. (Credit: Image courtesy of University of Utah)

The research is funded by the U.S. Army, which is interested in taking care of waste heat from radar, and also producing a portable source of electrical energy which you can use in the battlefield to run electronics. These devices could be used within two years as an alternative to photovoltaic cells for converting sunlight into electricity. The heat engines also could be used to cool laptop and other computers that generate more heat as their electronics grow more complex.

Using sound to convert heat into electricity has two key steps. University of Utah Physicist Symko and his colleagues developed various new heat engines (technically called "thermoacoustic prime movers") to accomplish the first step: convert heat into sound. Then they convert the sound into electricity using existing technology: "piezoelectric" devices that are squeezed in response to pressure, including sound waves, and change that pressure into electrical current. "Piezo" means pressure or squeezing. When heat is applied -- with matches, a blowtorch or a heating element -- the heat builds to a threshold. Then the hot, moving air produces sound at a single frequency, similar to air blown into a flute. Then the sound waves squeeze the piezoelectric device, producing an electrical voltage. It is similar to what happens if you hit a nerve in your elbow, producing a painful electrical nerve impulse.

Devices that convert heat to sound and then to electricity lack moving parts, so such devices will require little maintenance and last a long time. They do not need to be built as precisely as, say, pistons in an engine, which loses efficiency as the pistons wear. These devices won't create noise pollution. First, as smaller devices are developed, they will convert heat to ultrasonic frequencies people cannot hear.

Source : Science Daily

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