This is an excerpt from EERE Network News, a weekly electronic newsletter.

March 06, 2002

Have Scientists Found A New Version of "Cold Fusion"?

As renewable energy and energy efficiency continues to advance in strides, a new energy competitor may be on the horizon: a low-temperature means of achieving nuclear fusion. Research to be published in Friday's edition of the journal Science suggests that the explosive collapse of bubbles in a liquid may be able to trigger nuclear fusion reactions. Nuclear fusion, the source of energy for the sun, generally requires extremely high temperatures and pressures to occur.

The new research was driven by the phenomenon of "sonoluminescence" — the emission of light from the collapse of bubbles in a liquid. First observed randomly during studies of pumps, the phenomenon was reproduced in the early 1990s by passing sound through a liquid (a mixture of water and glycerin was found to work well). The results are intriguing to physicists, since a sound wave with a low energy density can create bubbles that emitted energetic light, suggesting that the bubbles were reaching temperatures of more than 10,000 degrees Celsius, and possibly more than 1 million degrees Celsius. This suggested that these small bubbles might get hot enough to achieve nuclear fusion. See "Sonoluminescence: an Introduction" on the Web site of DOE's Lawrence Livermore National Laboratory.

The new research — performed by scientists at DOE's Oak Ridge National Laboratory (ORNL), Rensselaer Polytechnic Institute, and the Russian Academy of Sciences — used acetone as the liquid, and replaced the hydrogen atoms in the acetone with deuterium, a heavy isotope of hydrogen that fuses more easily with itself to make helium. And although the experiment occurred at low temperatures, it was hardly a low energy process: the researchers bombarded the acetone with neutrons at energies of 14 million electron volts to help generate bubbles in the liquid. According to the researchers, small but statistically significant amounts of tritium were detected, suggesting that nuclear fusion might have taken place. However, the researchers have had mixed results when attempting to detect the neutrons that would be emitted by a fusion reaction.

The deputy director of ORNL suggests "a cautionary view" toward the experiments until further experiments can confirm the results — an understandable view, considering the controversy created by the announced discovery of "cold fusion" in 1989. If the research holds up, however, it will provide a new technique for creating nuclear fusion, a process that holds vast potential for energy production. See the ORNL press release.