May 25, 2007 — An appliance being designed for developing communities in Africa and Asia not only generates electricity, but also cooks and cools using acoustic technology.
The "Stove for Cooking, Refrigeration and Electricity," or SCORE, could help improve the health and quality of life for the two billion or so people in the world who cook over open fires. When used in enclosed places, smoke from such fires can cause health problems.
And these stoves are notoriously inefficient. A person can spend two hours a day collecting wood to burn in a fire that is so wasteful that 93 percent of the energy generated, literally, goes up in smoke.
"We make the burning more efficient so that they use less wood and have more time to spend on other things like education," said Paul Riley, the project director at the University of Nottingham in the United Kingdom.
The efficiency comes from a technology known as thermoacoustics, which produces sound waves from heated gas and then converts them to electricity.
Here's how it works: wood is placed inside the stove and burned. The fire heats compressed air that has been pumped into specially shaped pipes located inside the stove's chimney and behind the stove.
The heated air begins to vibrate and produce sound waves. Inside the pipes, the noise is 100 times louder than a jet taking off. But because the pipes are stiff and do no vibrate, the sound waves have nowhere to go. So outside the pipe, people hear only a faint hum.
