I agree 100%. You can't just say "X% better" without defining the specifics of the environment in which you're operating. If they're claiming X% better in all e

I agree 100%. You can't just say "X% better" without defining the specifics of the environment in which you're operating. If they're claiming X% better in all environments, they're absolutely, 100% full of shit and they either need to stop outright lying, or do more work to validate their mistaken claims. I'm not an ME or an expert in fluid mechanics, but I'm still curious. I wonder how the efficiency of this compares to maximum power point tracking coupled with variable pitch turbines (minimizes airspeed required to start, but adapts both mechanical and electrical parameters in order to have peak power transfer at every windspeed)? I wonder how the boundary layer introduced by the duct impacts efficiency. I understand there is a relationship between air velocity and efficiency, and I assume that it's easier to make high velocity systems more efficient, but in a ducted system such as this you're trading some of your total energy for a bigger pressure differential, and therefore speed. Is the amount of energy you're trading made up for by the gain in efficiency on the low-speed end of the curve? I imagine that on the high-speed (ambient wind, not flow over the turbine) end of the curve there's a drop in efficiency. It would be nice to see this quantified.