Its not a scam, the science and the principals have all been proven time and again. This is fact. When relating the cost and savings with our fuel prices Dr.. Frank surely must have figured the cost of the Genny (build, install, maintane etc..) and then added that cost to the cost of fuel.
When you introduce any thing new to someone, they always approach it with a degree of sceptacism. Rightfully so. Not all of us are true suckers. Sometimes we are led to believe things not JUST because of what they percieve as fact, but also through other psychological interpretations.
Bottom line, there are always going to be those who firmly believe as well as disbelieve. The proof resides in getting your hands dirty, your information factual, and the willingness to explore more than just a few avenues.
"You don't always have to know ALL the answers, but you do need to know where to find them."