There’s a bunch of reasons, starting with the traditional design of windmills. Long blades on high towers can’t withstand the kind of winds we get—ranging from 0-100mph in a few minutes at least a dozen times a year. As a result, the Oregon Energy Trust, which controls the development of wind energy in the state has not found a technology that they believe is safe, effective, and can withstand the gusts we have here.
There are many small wind systems that could be put on houses and commercial buildings, but they require consistent, fairly high wind speeds and their designs are hazardous for birds.
I’m working with some folks who think they may have found a solution. I’ll keep you posted.