This works fine as long as those who are investing money have unlimited opportunities to examine and dissect the workings of any such invention, or at least the plans if it hasn't been built yet. They would likely do so under terms of a strict NDA, and wouldn't be talking about it afterward, endorsements or otherwise. If the invention actually works as claimed, he wouldn't NEED to talk about it. Just set it up and start selling cheap energy at a rate below which all other conventional energy providers can compete at. That's the beautiful thing about energy. You don't HAVE to market it. People already want it and the lowest price will win out over all other factors, provided you're not doing something politically suicidal to fund/operate it.
Scammers tend to work in a different way though. They boast endlessly about their new product, and provide scripted demonstrations in very well controlled environments and prohibit anyone from having any physical access to the technology at hand, especially the investors. They then request large amounts of money to fund this slight of hand product. Most importantly, they never deliver.
The best scammers will use the investors' greed to their advantage. They offer up something that sounds generally reasonable considering the current state of technological advancement, but offers the opportunity to get a few years head start over the competition. To be ahead of the game in any emerging industry means you can make a 10fold return on your investment almost literally overnight. Many investors see that possibility as being worth the risk, since they falsely consider the risk to be the product not selling as well as hoped or perhaps not performing as well as promised. The fact that they were being duped from the beginning didn't factor into that assessment.
So, is this real? Probably not. If it were, we wouldn't be hearing about a "secret catalyst" that nobody's allowed to inspect, we wouldn't hear anything about the process at all. Or.. more likely, we'd hear about some experiment in a laboratory somewhere (probably at a school) where they discovered (probably by accident, or after a LOT of trial and error) some chemical arrangement that makes something like this work, ... and the best part of all, we always hear "maybe in 10 years, this technology 'MIGHT' be able to produce cheaper electricity". And then it goes through lots of peer review and refinement research. If it works, we hear more about it later, if not, well... we probably hear nothing at all. So this potential scammer, if he's actually legit, likely spent the last 20 years working in a lab somewhere, and did all of this work himself, bypassing the peer review process, collaboration with other scientists, or involving any lab assistants, TAs, students, etc. If so, that'd be a pretty important dot to look for on his resume, and it'd probably be a good idea to confirm it before writing any checks.