It's probably a scam. The inventor has kept the details secret so there is no way to independently verify that it is legitimate.
It's a scam
Demonstrations and experiments[edit]
Invited guests attended several demonstrations in Bologna in 2011.[34][35][36] The device has not been not independently verified. Of a January demonstration, Discovery Channel analyst Benjamin Radford wrote that "If this all sounds fishy to you, it should," and that "In many ways cold fusion is similar to perpetual motion machines. The principles defy the laws of physics, but that doesn't stop people from periodically claiming to have invented or discovered one."[37] According to PhysOrg (11 August 2011), the demonstrations held from January to April 2011 had several flaws that compromised their credibility and Rossi had refused to perform tests that could verify his claims.[2]
University of Bologna researchers have attended some E-Cat experiments, but only as observers. On 5 November 2011, the University of Bologna clarified that its researchers had not been involved in the demonstrations and that none of the experiments took place at the university. Rossi had signed a contract with the university, but the contract was terminated and no research was done because Rossi didn't make the first payment.[38][39][40][41][42]
Skeptic Ian Bryce believes that the E-cat is misconnected during demonstrations, and that the power attributed to fusion is supplied to the device through the earth wire.[43][44] Dick Smith offered Rossi one million dollars to demonstrate that the E-Cat system worked as claimed, while the power through the earth wire was also being measured, which Rossi refused.[45][46] Peter Thieberger, a senior physicist at Brookhaven National Laboratory, said it would be very difficult for this misconnection to happen by accident and that the issue could only be cleared with a fully independent test.[43]
Another demonstration on 6 October 2011 reportedly lasted for about eight hours.[47][48][49] Roland Pettersson, retired Associate Professor from the University of Uppsala, who witnessed it said "I'm convinced that this works, but there is still room for more measurements".[19]
On 28 October 2011 the unit was "customer tested" and was said to release 2,635 kWh during five and a half hours of self-sustained mode, an average power of 479 kilowatts – just under half the promised power of one megawatt. Independent observers were not allowed to watch the measurements or make their own, and the plant remained connected to a power supply during the test allegedly to supply power to the fans and the water pumps.[50][51][52][53]
https://en.wikipedia.org/wiki/Energy_Catalyzer
