The US government spent a large amount of money (probably more than a billion dollars) during the late seventies and eighties creating experimental windmills for testing their practicality. But researchers only studied two blade systems. The results were worthless, in spite of having tested dozens of windmills. None of the experimental windmills were designed for good overall efficiency, and the most important questions were not studied. Three blade systems are used on wind farms.

The environmental benefits of renewable sources of energy, like windpower, include very little, if any, byproduts and pollutants.