I've been following this guy's work for some time now. I'm certain that "free energy" is not only possible, it's already been developed, kept secret, and is being used extensively in so-called "black projects". That said, I'm not sure whether Keshe's work is legitimate or not. When he made his "big announcement" and wanted to exchange his technology for peace contracts last October, he supposedly sold a large number of units to the Italian government for production. I expected a very quick disclosure process and subsequent socio-economic changes as a result. Unfortunately, that hasn't happened yet. And since then, I've heard nothing from anyone except his critics.
I'm still keeping my finger crossed that this will pan out soon though...