The reason cold fusion (or if you want, call it “LENR”) is impossible has been explained many times.
Shoving two particles of the same polarity together to form an atom of a different identity—e.g. shoving nickel and hydrogen together to form copper—takes a LOT of energy.
Mathematically, the process is impossible. But math is sometimes imprecise.
When the particles are far apart, it is easy to push them together. But it becomes logarithmically more difficult the closer they get, until the energy required asymptotically approaches infinity. That energy barrier is what people refer to as the Coulomb force. In reality, at very high temperature (like that found inside a star), it is possible to overcome the Coulomb barrier on very small atoms—like a hydrogen and a helium, which have +1 and +2 charges, respectively—because the high temperature represents a huge amount of energy. But, as I saw two physicists describe it in a blog, there isn’t enough energy in the universe to overcome the Coulomb barrier of a nickel nucleus (charge of +28).
And that is why Rossi’s claims are not believable.
Did I say that was going on? Try this one. You have an atom of hydrogen ~ actually, it’s in a molecule of hydrogen. You slip another proton in there to get deuterium. What you have to do is overcome the Coulomb Barrier ~ (SEE http://en.wikipedia.org/wiki/Coulomb_barrier ) which requires a great deal of energy BUT under certain conditions quantum tunneling is available (SEE http://en.wikipedia.org/wiki/Gamow_window ) There are a variety of descriptions of what seem to be other techniques which amount to the same tunneling trick.
So who were these physicists?