For those unfamiliar with the subject (where have you been?), Cold Fusion proponents claim that they can make nuclear fusion reactions run at room temperature using what appears to be a modified electrochemical cell rather than the 4 storey-high extreme condition nuclear accelerators that have been used in conventional physics.

In 1989, Martin Fleischman and Stanley Pons, both respected chemists at the University of Utah, made perhaps the most controversial announcement the world of science has ever known. They claimed that the electrolysis of heavy water using a palladium electrode produced an anomalous heating effect and attributed it to the nuclear fusion of deuterium. This resulted in a media feeding frenzy, complete with inflated claims that so-called cold fusion could provide the world with cheap abundant energy and/or nuclear weapons.

Unfortunately for Fleischman and Pons, numerous attempts to replicate their experiments ended in failure, resulting in accusations of incompetence and/or fraud and the name "Cold Fusion" has been synonomous with career suicide in the scientific comunity ever since.

However, a small community of true believers has continued to beaver away. David Nagel is obviously one of them despite a thoroughly credible background in engineering materials and condensed matter science. Nagel obviously understands the problems inherent in dealing with the legacy of Fleischman and Pons and is able to retain his sense of humour.

"There are two major problems with LENR. One is the imperfect reproducibility and control of the experiments. The second is that there is little substantive theoretical guidance for the phenomenon". Nagel likens the first problem to having a car that turns on when it wants and goes where it wants. He would like to tackle the problem by improving the metrics, as most cold fusion experiments have continued to rely on simple temperature rises as a measure of success.

In very brief, the original theory behind cold fusion proposed that it was all down to packing the palladium with deuterium. Conventional chemistry holds that when 2 electrodes, one made of platinum and the other of palladium, are immersed in a solution of heavy water (deuterium oxide), and a voltage passed between them, the heavy water breaks down to give oxygen and deuterium. Pons and Fleischman claimed that if the process went on long enough, the palladium electrode would eventually become so packed with deuterium atoms that the atoms would fuse together, generating heat energy (the temperature rise).

This does not agree with conventional physics - which says that atomic nuclei repel each other with tremendous force. Traditional fusion experiments rely on overcoming these forces with kinetic energy; hence the giant particle accelerators.

Another of the major theoretical problems with cold fusion has always been the absence of high energy gamma rays which the deuterium fusion reaction should produce. Nagel is a proponent of the lattice theory, which explains this away.

The lattice theory was first proposed by Nobel Laureate Julian Schwinger in 1994. He suggested that the crystal lattice structure of the palladium is able to absorb the gamma radiation and convert it into heat with no residual radiation. P gets very fuzzy at this point as it starts going into quantum mechanics and Einsteinian paradoxes, but suffice it to say that the point is being argued by opposing camps of theorists.

Indeed, it is quite ironic that nuclear fusion seems to have inspired so many splits in the scientific community; splits between physicists and chemists, between theoreticians and engineers, etc etc.

However this has not stopped a slew of venture capitalists and startup companies from taking up the cause over the years. While some, like Californian startup Clean Energy Technology have gone belly up over the years, others like Lattice Energy in Chicago may yet succeed.

So, are cold fusion proponents crazy garage scientists or true visionaries? Only time will tell.