The article has no information about how the system works, and they didn't show a prototype. They only claim to have one that worked for 27 hours, but it's not clear how much power it was providing and they have no independent verification.

I'm trying to guess, but since one of them has a background in pneumatics, perhaps they are storing energy compressed air.(?????) They say something about magnets, but I don't have any idea how they could possible use magnets, so I count it as a red flag. Namedroping Tesla is another red flag.

I tried some googling, but I didn't find anything. If you get a better press coverage, or a link to the patent, or something more technical perhaps I can give it a try.