Does not exist. Free energy does not exist. Zero point energy does not exist.
If ever someone claims they ‘discovered’ free energy, they did not. The least breakable of all laws of physics is the second law of thermo. There’s something missing from this, or it won’t work.
If I may speculate, with only have read non-sciency papers, the powersource may be a thermal device, or it may be a mechanical device based on deformation. Either way, Energy in >= energy out (if we neglect heat losses, leakage, etc). Saying ‘physicist discovers’ or ‘graphene’ doesn’t break the 2nd.