Ah, there's no better prototyping tool than duct tape. Other common items like hot-glue and WD40 just don't stand a chance.
Agree: the Savonius will win when it comes to "excess" energy among VAWT's. There's the energy needed to keep the machine spinning, and then an "excess" that will accelerate it, if there is any.
If not, well it just wallows along. If it wallows, don't bother putting a generator on it because it doesn't have any power to spare.
MJ: Red Green has been off the air for many years, and supplies of duct tape have (slowly) recovered since then.