> As noted in the article, wind can be highly variable in most areas. Optimizing a wind turbine for the average low speed (like here in the US Midwest) means that at super high speed winds can damage your turbine and it may need to be shut off. If you optimize for the high speeds you can get a ton of energy at those speeds but your turbine will mostly be still. Regions with a nice steady wind profile work better for power generation.

This problem is solved centuries ago. Just cover only part of the blade with cloth.