I have been following this quite closely for sometime. First it is not really fusion in the quantum mechanics sense. Better referred to as LENR. Quite a few researchers are on the verge of mastering LENR but none of them can explain what is actually going on. Rossi has demonstrated a 1 MW unit (made up of multiple smaller units inside a container) for the scientific community and the press and no one can seem to find a hole in his process. He uses a catalyst (not divulged), a small amount of nickel powder and electricity to start the process of converting the nickel to copper isotopes and back. It seems like the process could be self sustaining but Rossi depends on the electric input (I suspect) to be able to keep the process under control.
It should be noted that the circumstances around the debunking of Fleischman and Pons in 1989 are far from admirable. First they were forced to announce too early by university politics. Then MIT endorsed the concept and recanted three days later when they realized how much their bread was buttered by the study of hot fusion. Many many people do not want this thing to come to fruition.
The size of a "reactor" (it takes about 30 of them to make a MW) is the size of an ink cartridge if you take away the heat exchanger and the lead shielding. About the size of a carry on suitcase with all.
Rossi has limited himself to marketing a "furnace" for the time being. The imposed limitations on process control seem to create temperatures that are on the low side for making electricity. Electricity will come but not until some experience in process control is in hand.
I do not think this is a scam but it could take years to mature. Or not....
In the mean time I am exploring thermo-electric technologies that convert heat to electricity without going through a turbine.
I will end this post by saying that my first response to another report from Taiwan about an LENR system was that it was a scam. So I do not fault anyone who thinks Rossi is perpetuating a scam. But I would say look a little deeper before jumping into the fray. There is something going on here and it could be pretty exciting.
I can see absolutely no reason to believe this. Rossi's drawn out explanation of the math (which any high school physics student could do in less than one minute, rather than the 12 minutes required by Rossi) suggests that there are a lot of theatrics being used to cover up something. The demo video screams hoax: the amount of steam created is clearly in line with the input power, not the claimed output power. (PhysOrg points this out, too.) It looks just like a 600 watt electric water heater to me, with the hydrogen, nickel, copper, etc all magic-trick distractions.
The simple fact that the key output is just led to a drain says that the test is intentionally invalid. The old "professor" (who has a hard time understanding that Rossi swaps commas and decimal points inconsistently) cannot claim to be knowledgeable but simultaneously oblivious to such bad experimental design. The experiment is designed to obfuscate, it seems.
Extremely hard to take any of this seriously. The unit takes in 600 watts, and outputs 600 watts worth of steam -- that is all the video shows.