The fact that Celani had demonstrated modest but well-publicized positive results a decade ago - using an alloy of copper and nickel as catalyst is probably important in understanding what is going on today with the Clean Planet technology.
Clean Planet apparently used that information from Celani to optimize and boost whatever thermal gain reaction is happening. Trial and error - not theory. Very Edisonian approach. They merely improved what had already been demonstrated as possible - and it could have been simply luck and persistence - instead of having a correct understand of the real mechanism, which still eludes us. It is possible that even better results could now be engineered with additional layers maybe even including Pd or Au - we do not know what trials CP have done to get this far - and have discarded along the way, IOW by starting with a small gain and modifying the structural options - this time by using thin alternating layers of copper and nickel as your catalyst - instead of an alloy (a mix) - they are able to turn an interesting but minimal reaction and anomaly into what we hope is leading to a commercial product. Robin wrote I find the necessity of combining Cu & Ni somewhat puzzling, though some neutron exchange mechanism mediated by Hydrogen might make sense. I wonder if it works with either Ni or Cu alone? Using alternating very thin sheets implies that's it's a surface phenomenon, that occurs where the two different metals come into contact with one another. > It looks to me like the Clean Planet group of Japan is the closest to getting > an actual device to market.