Earlier I said that I do not know the limits of self-sustaining operation and it might go on in that mode indefinitely. Recently, Rossi said that the limit for this particular machine is around six hours. I do not recall where he said that but I am sure he did.
Some people have said he should have left the October 6 test run in self-sustaining mode for longer than four hours. That would have been nice, but apparently it was close to limit, and it would need to go back to a controlled mode. It is unclear how long the controlled phase is needed before input power can be turned off again. Rossi often makes dubious statements about business or nuclear theory, but as far as I know his assertions about the engineering aspects of his devices have all been accurate. I have no reason to doubt this. This is no indication that the technology is fundamentally limited to a six-hour duty cycle. Arata's cells have stayed warm much longer than this. Granted they are Pd-D which might be very different from Ni-H. There is absolutely no indication that the current ratio of 1 W input to 6 W output for most cells is caused by fundamental performance limitations or physics. As I said, this is a lot like saying that railroad locomotives will never go faster than 18 km/h because that's how fast the first one went in 1808. If the 1 MW reactor is run in self-sustaining mode for several hours that would certainly be a good test. >From a technological point of view, there is no advantage to having cells go into fully self-sustaining mode. Having a small amount of power to control the cell is just as good as having no power at all. The overhead equipment cost of generating control current with thermoelectric devices will be trivial, and the dollar cost for the energy will be zero. I am sure the control current will ultimately be much smaller than the overall output. - Jed
