The E-Cat unit, invented by Andrea Rossi and Sergio Focardi operates on nickel powder and hydrogen, along with a catalyst. Some speculation has been that rather than the commonly found hydrogen, the device probably uses less plentiful deuterium.
While Rossi is very closed-mouthed about the details of his device, it has been made very clear that deuterium is not the material being used here. In addition, some people have speculated about the form of the nickel, but Rossi has confirmed that it is, indeed regular nickel.
When asked about the safety of the materials, since nickel powder is toxic, Rossi has answered that the fuel cells are sealed cylinders. When they are fully depleted, the cylinders can be safely disposed of with no radioactive waste involved.
In hot fusion nuclear reactors, the “melt down” is a fearsome thing. Failure of any of the safety precautions can cause catastrophic failure. However, with the E-Cat, if the temperature exceeds safe limits, the nickel melts. Once the nickel melts, it expels any absorbed hydrogen, effectively halting the reaction.
Some have expressed concerns about the gamma radiation emitted by the E-Cat. However, the lead shield contains the gamma rays. This lead shield remains at or below 200 degrees Celsius at all times.
The E-Cat has a self-sustained mode which will keep it going during a short blackout. If there is a longer blackout, the safety system will shut off the system in a one hour long process. The restart is also a one hour long process, and is done manually or through cell phone transmission.
The power transmitted by the unit is adjustable, so that it produces only as much power as the situation needs.