Magazine article UNESCO Courier

Cold Fusion - a Storm in a Test-Tube?

Magazine article UNESCO Courier

Cold Fusion - a Storm in a Test-Tube?

Article excerpt

It seemed like a dream come true. Two chemists had come up with a cheap, simple, clean and virtually inexhaustible source of energy. If it had been true, and could have been made to work, it would have solved the energy problems of humankind for far into the future.

But science does not usually yield such easy solutions, and this case was no exception. It is fairly certain now that the so-called "cold fusion" phenomenon was, not the breakthrough it was initially claimed to be. No one is yet certain what the phenomenon is or even if there is a phenomenon at all, but the events that have surrounded it since last year hold many lessons for those who practice science.

Martin Fleischmann of Southampton University and Stanley Pons of the University of Utah, both respected scientists in the field of electrochemistry, announced on 23 March 1989 that they had achieved nuclear fusion in an electrolytic cell. They had filled the cell, similar to a glass beaker, with a solution made from heavy water, in which the hydrogen in the water molecules is a rare form known as deuterium. They immersed in this solution two electrodes, one of platinum and one of a metal called palladium. They passed an electric current through the solution by connecting the electrodes to a battery. After some time they found that a large amount of heat was being produced in the cell, much more than that generated by the power of the battery.

Their explanation was simple: passing an electric current through the solution freed the deuterium from the heavy water molecules and it was then absorbed into the palladium electrode. Once inside the electrode, they claimed, deuterium atoms f used together to form larger atoms of helium and released energy in the process. This nuclear reaction is the same process as that which fuels the sun and other stars as well as providing the destructive power of the hydrogen bomb.

It was in the 1920s and 1930s, when scientists were probing the atomic nucleus and piecing together its structure, that they realized that reactions between nuclei could release large amounts of energy. Nuclear fission is the reaction where a large heavy nucleus splits apart into two or more fragments. A working fission reactor was first demonstrated in 1942, and in 1945 fission was put to lethal use over Hiroshima and Nagasaki.

Nuclear fusion is the binding together of small light nuclei and is the basis of the devastating hydrogen bombs developed in the 1950s. Scientists have been trying for the last thirty years to harness nuclear fusion as a peaceful source of energy, but the methods they have been using are still probably decades away from success. Fusion has certain advantages over fission as a source of energy: it produces little in the way of radioactive waste and its fuel is deuterium and another heavy form of hydrogen known as tritium, both of which can be extracted in great abundance from seawater.

The problem in achieving fusion is getting the nuclei close enough together for them to fuse. Nuclei are composed of protons, sub-atomic particles which have a positive electric charge, and neutrons, which are neutral. Nuclei thus have a net positive charge and, like similar poles of a magnet, two positive nuclei will repel each other. This repulsion, known as the Coulomb barrier, is very strong, and scientists have tried to overcome it using huge fusion reactors about the size of an office block.

There are a number of such reactors in the United States, the Soviet Union, Europe and Japan. They are used to heat up a plasma, a charged gas, of deuterium and tritium to enormous pressures and temperatures, comparable to conditions in the interior of the sun, and they confine the plasma with strong magnetic fields. Under these conditions, nuclei collide together with such force that fusion reactions do take place, but in current machines the amount of energy put in to create the reaction is greater than the energy produced by the fusion so they are not yet feasible as sources of energy. …

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