Before we get too excited about the commercialization of cold fusion — which would probably be the biggest technological advance since writing or agriculture — we should remember that Rossi is still being incredibly opaque about how his cold fusion tech actually works. ........One of the science community’ biggest sticking points about Rossi’s cold fusion devices is that he hasn’t proven that his LENR is self-sustaining. Despite a huge amount of output energy, the device still needs to be connected to the mains.