A minor quibble over the use of "efficiency" in the thread title, and in a couple of comments.

When there's a lot of something available, and immediate purposes only need a little of it, efficiency isn't too important. You can take a lot, even if you only manage to use a little, with efficiency being the ratio of what you use to what you destroy to get it.

What's really being discussed is just usefulness, and as has been pointed out individual wind turbines are only useful to a few who happen to be living where conditions are peculiarly suitable.

For individual wind power applications there is also the consideration that your wind turbine may interfere with the one on your neighbor's roof, by deflecting or otherwise modifying the local circulation, so while a few people can have them, they can't possibly be a generally useful solution for "the masses."

It's also fine to push for one scheme over another, and water power, whether using streams and dams or tidal sources is a good one, and has been for centuries. The "efficiency" claims for water vs wind are not really much of an argument. An air-extractor can be just as efficient (arguably more efficient) as a water kind. The efficiency is the ratio of the usable power obtained to the reduction in "power" in the environment. Unless one speaks of extracting all the power of the tides, or bringing all the winds to a halt, it's not an appropriate term.

It is encouraging to see recognition that regardless of how "clean" a novel source is there are limits on how suitable it is for use by most individuals, or even for large numbers of individuals.

That point is frequently ignored.

John