A fairly recent development is Rossi's E-Cat cold fusion system which has now been tested by a third party.
"Now, Engineer Mats Lewan from the Swedish publication, Ny Teknik, which means "New Technology", published weekly for over 40 years, has released results from two separate tests of the E-Cat he performed in Bologna, Italy. These latest results confirm those from previous testing, that the system outputs at least 6 times more energy than it consumes. "
