This is not quite true. There have been required advances in materials science over the last decades that are needed to maintain the size/strength:weight ratios/etc. The larger the wind blade the more efficient.
Those required advances would have materialized -much- sooner if windpower had been taken seriously and some (let's say) 500Kw mills had appeared on the market. I recall Reagan having Carter's White-House-rooftop solar removed. Anything green was mocked as a 'utopian dream' or whatever, and the established industry spent -a lot- of money keeping it that way.
These days, when the alumni mag from my school arrives, I have to ruefully smile about all of the 'green language' in it, now that it's trendy. What a damn shame.
