Cold fusion

What is cold fusion or rather what is it supposed to be?

Firstly, some basic physics: an atomic nucleus is made up of proton(s) and neutron(s) surrounded by an electron cloud. The protons and the neutrons within the nucleus are bound together by the so-called strong nuclear force.

Hydrogen, the simplest nucleus, has only a single proton. Helium is the next ‘heaviest’ element with two protons and two neutrons (⁴He) – another variant, the less abundant isotope ³He, has two protons and one neutron. There are close to one hundred different elements and as well as a number of variant isotopes†.

Most stars consist largely of hydrogen, usually with no more than 25% of their mass made up of helium (and a small component of heavier elements) and are held together by gravitational attraction producing core temperatures and pressures so high that the electrons of atoms are stripped from their nuclei (ionized) forming a plasma of electrically-charged particles. Temperatures at the centre reach extremes in the millions of degrees (C) generating high energies and speeding protons causing particle collisions which in a small number of cases result in a fusion into deuterons (²D) – heavy isotopes of hydrogen comprising of one proton and one neutron – overcoming electric repulsion (typically positive charges of the particles) and releasing energy in the process.

This same nuclear fusion process which is the ‘engine’ of stars is also what drives the explosive reaction of the “hydrogen bomb”, nuclei of deuterium fuse together into helium. Controlled fusion has been seen by policy-makers as a very desirable energy source here on earth – the fuel is available, a certain amount of water occurring naturally is deuterium-based rather than hydrogen-based, and hence is called “heavy water” – and the process produces very significantly lower levels of radioactive waste in contrast to the considerable radioactive waste accompanying electricity generation from the nuclear fission of uranium.

Unfortunately, the pathways to facilitating fusion have been limited to achieving and sustaining high temperatures as the way of forcing protons close enough for fusion to happen or high-energy particle acceleration: so-called hot fusion, hardly simple, straightforward, or as yet economic approaches. The challenge entails creating a stable high temperature and density initiating a self-sustaining fusion reaction which can be conveniently maintained. The practical issues in the way of achieving this have been immense, with many technical problems stemming from the method used to contain the plasma field. If it is ever achieved in a sustainable way hot fusion would give us a cheap, relatively non-polluting, and virtually unlimited supply of electricity. However, at present it is reasonable to say that such research in plasma physics is still in its infancy and actual generating power plants seem a long way off.

“Cold fusion” holds the promise of a room-temperature process without the complications and problems which have beset, and are still being overcome, in the “hot” version of fusion. And in the form put forward in claims made by Utah chemists Martin Fleischmann and Stanley Pons in March 1989, by press conference no less, requires little more than a standard electrochemical cell – two electrodes (one containing palladium) lying in an electrolyte solution (in part of heavy water) connected to a battery – a bench top arrangement which is supposed to produce an electrochemical reaction in the cell within which the building up of deuterium in the palladium electrode reaches a point where the nuclei become close enough to fuse.

These experimentalists did not “stay their hand” in their announcement of their revolutionary work by having it fully scrutinized through the peer review process and published in a scientific journal from which journalists would then have had the journal article as their source.

Suffice to say that the claims made for “cold fusion” by Pons and Fleischmann did not withstand scientific examination and replication. As has been pointed out the theoretical framework seemingly used by these chemists to understand how such a process could work is murky, which isn’t to say that cold fusion is impossible, but a clearer understanding of well-understood physics may have prevented their big, and quite spectacular, scientific “belly-flop”!

Some defenders have said that those who have stood by what was announced in 1989 will in the end have the last laugh. It would certainly be good news for efforts to mitigate the effects of Global warming if it were true – unfortunately this is almost certainly no more than wishful thinking.

For an account of the fiasco see:

What ever happened to cold fusion? by David Voss

and:

an article by David Goodstein

(see also: pseudo-science, Distinguishing Science and Pseudo-science)

†varieties of atom having the same number of protons in the nucleus (and therefore are the same element) but differing in the number of neutrons.

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