A friend of mine recently bent my ear for an evening over cold fusion. It struck me as pseudo-science, but not wanted to be prejudiced, I spent some time with a web browser looking into it.
Though I still have a hard time believing some of these claims, I have to admit that this technology shows promise.
The Coulomb barrier that must be overcome to fuse two protons is about 5 MeV – not something you’d expect at room temperature, but well within the range of a standard particle accelerator. The problem is the minute cross section of the nucleus – protons with enough energy to fuse are far more likely to be scattered away from each other unless they are precisely aligned in a head-on collision.
That’s where the cold fusion claims start to get interesting. All of the cold fusion reports that I read involved palladium as a catalyst. Now palladium has the unusual property that it can absorb significant quantities of hydrogen. There doesn’t seem to be a consensus on exactly how this works, but one explanation is that the hydrogen nuclei can move fairly freely within the palladium crystal mesh. Now if I wanted to line something up at atomic dimensions, a crystal would be the obvious choice, and if I wanted to line something up while its moving, then I would want a crystal that allowed my particle mobility. So palladium seems like an obvious choice to line up moving protons to precisely collide them.