There has been a lot of speculation lately on the Journal of Nuclear Physics concerning how much mass is depleted during the workings of an E-Cat or Hot Cat. Andrea Rossi has stated that it is virtually impossible to measure the amount of depletion of the various masses within the units. He informed Dr. Joseph Fine just recently that there is no depletion of the catalyst mass. Hydrogen and nickel are expected to be depleted, but a certain amount is converted to either copper or zinc. Rossi has said that over a 6 months period, there is about a 175 milligram difference in the weight of the masses in a 1 MW unit.
However, Steven Karels pointed out that:
“…you have 100 10kW eCat units (or more) within your 1 MW system. If you have 10 to 16 “mini-e Cats” within one 10 kW eCat, then there are between 1000 and 1600 “mini-eCats” in the 1 MW system. So. The mass loss per “mini-eCat” would be 175 micrograms. If there is 5-10 grams of “fuel” in each mini-eCat, you are looking at a relative mass change of 1 part in about 6000 change. I think it would be difficult to detect.”
Rossi agreed with Karels. In addition, such small amounts would be hard to measure within any rate of variation.