Add in a car radiator fan @1800 CFM and a 20W solar panel and the turbines work even better.
This brings up an interesting problem. If there is any type of power ventilation, placement is important. Studies have shown that the power ventilators often cause air to be drawn in through other nearby high vents, and cause relatively little air to be drawn in through the soffit vents. This can significantly reduce their effectiveness of ventilating the attic.
Adequate soffit and ridge/gable/hat vents allow for natural convective airflow that is not subject to mechanical failure, costs very little, and has reduced potential to draw conditioned air from the dwelling through the hundreds of gaps and cracks existing in the typical home.