Two scientists at Los Alamos National Laboratory have developed a low-tech engine that performs work using simple sound waves and has no moving parts. Scott Backhaus and Gregory Swift believe it has the potential to provide alternative energy, significantly save energy supplies and reduce global pollution. They said in their study published Thursday in the journal Nature that the revolutionary engine, which is as efficient as a typical car engine, might be used to cool refrigerators or to cryogenically recover a form of natural gas wasted and burned off in oil production. That is, they could be used to generate electricity while at the same time to produce heat for warming the home or for hot-water heating.
Electronic devices generate sound waves, which stimulate the gas to alternately expand and contract.
The engine's operation is based on the Stirling principle, named for the Scottish 19th century scientist Robert Stirling, who showed that a confined volume of gas expands at high pressure and contracts at low pressure, creating an alternating cycle that can do work when the gas is heated or cooled through exchangers. In a separate article published in the same issue of Nature, the research is praised for its ingenuity and environmentally favorable qualities by Steven L. Garrett of the acoustics program at Pennsylvania State University. Garrett expresses admiration for the invention's simplicity, efficiency and lack of environmental intrusiveness. An obvious drawback of the new thermo acoustic engines is that acoustic amplitudes can reach levels of 190 decibels.