Nuclear fusion has long been thought to have the potential to be a cheap and virtually unlimited source of energy. However, fusion requires extremely high temperatures or pressures. Cold fusion is fusion occurring at moderate temperatures and pressures. Cold fusion could make fusion more practical.
Fusion refers to a process where atomic nuclei collide and fuse together, forming larger particles and releasing energy. The fusion of hydrogen nuclei inside the sun is what makes the heat that warms our planet. But outside the enormous pressure in the center of a star like the sun, nuclei are unlikely to fuse. All atomic nuclei are positively charged, and thus repel each other. Some outside force, such as high temperature or pressure, is needed to make the nuclei overcome their natural repulsion and come together. If nuclei could be forced to fuse at low temperatures in a practical device, it would be possible to produce large amounts of energy at a reasonable cost.
One of the fathers of modern physics, Ernest Rutherford, investigated the possibility of cold fusion using deuterium (an isotope of hydrogen) atoms in 1934. However, he could find no viable method for achieving fusion at low temperatures.
Meanwhile, experiments with high temperature fusion proceeded. In the 1950s, scientists experimented with magnetic bottles as fusion devices. Theoretically, gas could be heated to such high temperatures inside the magnetic bottle that hydrogen nuclei would fuse, as they do in the sun. A physics laboratory at Princeton University in Princeton, New Jersey, built a magnetic containment device, a massive machine called the Tokamak. It did produce some energy from fusion, but using the Tokamak or anything like it as a power source is not practical, since it requires more energy to make fusion happen than it produce from the fusion reaction. Scientists continued to research various methods of fusion. If energy could be produced from an abundant material like hydrogen or deuterium, the earth would have an almost limitless, new, clean power source, the thinking went. The potential benefits were enormous.
Since cold fusion would operate at low temperatures and pressures, it would not require the expensive and complex equipment needed for high temperature fusion. Cold fusion research was filled with disappointments and dead ends, but scientists continued to experiment. Cold fusion has been called the "Holy Grail" of physics, because it seems virtually unattainable.
In 1989, Stanley Pons and Martin Fleischmann, two electrochemists working at the University of Utah, stunned the world with their announcement that they had performed cold fusion in a plastic dishpan using a small laboratory device. Pons was a prolific researcher in electrochemistry, and Fleischmann was an esteemed member of the British Royal Society and a professor at the University of Southampton in England. The two had collaborated for years, and in the mid-1980s Fleischmann had become a visiting professor at Utah. Their device electrically charged a cathode made of palladium, a metal that contains high concentrations of hydrogen isotopes. Apparently aiming to protect their patent rights to this revolutionary device, Pons and Fleischmann made their first cold fusion claim directly to the popular press, bypassing the scientific community by not submitting their discovery first to a professional journal where it would be reviewed by other scientists.
Pons and Fleischmann were temporarily heroes, appearing before Congress to help the University of Utah secure funding for cold fusion research. Meanwhile, many experts in fusion research and other physicists were less easily convinced. If the palladium cathode was actually fusing hydrogen isotopes, it would have emitted dangerous levels of radiation. The very fact that the clearly healthy scientists had been photographed beaming next to their cold fusion machine alerted knowledgeable people that the device could not be working as Pons and Fleischmann claimed. Within weeks it became clear that Pons and Fleischmann had made some elementary mistakes. It was thought that the energy increase they detected came from pockets of heat in the fluid, caused by the liquid not being stirred enough. Although a number of scientists around the world continued to research it, within ten years of the Utah experiments the discovery of cold fusion seemed to be discredited.
Pons and Fleischmann suffered a serious loss of reputation after the cold fusion debacle, ultimately losing a libel suit they brought against an Italian newspaper that had labeled them frauds. The Japanese government continued to support cold fusion research through much of the 1990s, but finally abandoned all its financial support in 1998. It seemed that only a few hundred scientists worldwide were working on cold fusion in 2001, judging from attendance at a semi-annual conference on the topic. In 2002, a researcher at the Oak Ridge National Laboratory in Oak Ridge, Tennessee , claimed to have detected something that might have been cold fusion using a process called acoustic cavitation. This produced high pressure in a liquid by means of sound waves. But with the stark example of Pons and Fleischmann, any new claim to cold fusion will have to be carefully substantiated by a number of scientists before it can overcome existing skepticism.
[Angela Woodward ]
Park, Robert. Voodoo Science. Oxford: Oxford University Press, 2000.
Taubes, Gary. Bad Science: The Short and Weird Times of Cold Fusion. New York: Random House, 1993.
Beals, Gregory. "Pining for a Breakthrough" Newsweek 138, no. 16 (October 15, 2001):57.
Goodwin, Irwin. "Washington Dispatches" Physics Today 51, no. 7 (July 1998):48.
"Here We Go Again" Economist 362, no. 8263 (March 9, 2002):77.
Pollack, Andrew. "Japan, Long a Holdout, Is Ending Its Quest for Cold Fusion" New York Times (August 26, 1997):C4.
Cold Nuclear Fusion
COLD NUCLEAR FUSION
COLD NUCLEAR FUSION, an intensely disputed and largely discredited method for generating thermo-nuclear fusion at room temperature conditions. In nuclear fusion hydrogen atoms merge to form one helium atom, releasing energy. In its conventional form, such as that occurring within stars and hydrogen bombs, nuclear fusion requires high pressure and temperature, which force the atoms together. Proponents of cold nuclear fusion maintain that certain catalysts can coax hydrogen atoms to fuse without extreme pressure or heat. One form of cold nuclear fusion, known as muon-catalyzed cold fusion and first suggested in the 1940s, is undisputed. The process, in which a subatomic particle known as a muon captures two hydrogen atoms and forces them to fuse, has been demonstrated in the laboratory but appears not to be feasible as an energy source. The controversial form of cold nuclear fusion was first heard of in March 1989, when two University of Utah chemists, Martin Fleisch-mann and B. Stanley Pons, reported that they had produced fusion in a test tube at room temperature by running an electrical current through heavy water, a type of water in which the hydrogen atoms are of the isotope deuterium. They claimed that the current drove the deuterium atoms into a palladium rod in the water, forcing the atoms to pack closely enough to fuse. This announcement raised a furor in the scientific community. After other researchers failed to obtain similar results with the technique, a consensus emerged that the Utah scientists had used a flawed apparatus and misinterpreted the data from the experiment. A small but vocal minority of researchers continued to pursue variations on the approach.
Huizenga, John R. Cold Fusion: The Scientific Fiasco of the Century. Rochester, N.Y.: University of Rochester Press, 1992.
Mallove, Eugene F. Fire From Ice: Searching for the Truth behind the Cold Fusion Furor. New York: Wiley, 1991.
See alsoPhysics: Nuclear Physics ; Scientific Fraud .