This "cold fusion" reaction is far less dangerous than the nuclear fission that occurs at existing nuclear plants. If a catastrophe occurs and the reactor chamber breaks and spills its contents, the device would turn off immediately and the reaction would simply cease. Since there are no radioactive materials or radioactive waste, nothing bad would be introduced into the environment and no danger would be posed to humans or the environment by the device's failure.
Another important point is that these units have the potential to decentralize power generation. In other words, instead of tens of thousands of people relying on a single electrical power plant linked by miles of transmission lines, each individual household could potentially be powered by a relatively small E-Cat device which could fit in a space the size of a closet.
Ross-Focardi Energy Catalyzer
At the heart of the reaction is the catalyst (or catalysts), which are key to the whole process. Right now, the catalysts are intellectual property and are being kept secret, at least until a Rossi can obtain a full patent on the system. Only Rossi and a few of his close business partners know the identity of the proprietary catalyst(s).
On January 14, 2011, Rossi and his colleague Sergio Focardi demonstrated a small working version of the Energy Catalyzer at the University of Bologna, Italy, that produced more than 10 kW of heat power for an hour, while only consuming a fraction of that amount of energy to run. The device takes about 400 watts/hour to run, but produces 15,000 watts/hour of energy. In other words, it takes the equivalent energy of about four 100-watt light bulbs to produce 150 100-watt bulbs' worth of power –- 37.5 times more output than input –- a fantastic rate of return. The inventors calculate that one gram of nickel in the E-Cat can produce the equivalent energy of 517 kilograms, or about 1,140 pounds of oil. A gallon of oil weighs roughly 6-8 pounds depending on its density, so one gram of nickel in the table-top sized E-Cat can produce about the amount of energy generated by about 142 gallons of oil.
http://www.prwatch.org/news/2011/04/10661/media-ignores-energy-breakthrough-worry-free-nuclear-power