I have put a lot of thought into this, and done a lot of research, but I have never built anything (yet).
I live on a big hill and they were going to install (3) massive wind turbines on my
land until the town vetoed the plan, so I definitely have the wind potential here. And here, my biggest living expense is in heating my home, or making
hot water for domestic use,, so to use wind to heat
water would behoove me.
One idea I had, was to make a windmill pull a weight (plunger) up, then drop it so that as it dropped by gravity, it would displace oil and pump it through a relief valve. I noticed the hydraulics on my
tractor gets very hot when I put the hydraulic system in relief, so the oil in a closed circuit plunger system would also get hot. If that oil circulated through a bath of water, it would not take long for that water to get heated up. That could be then put to use. I see no reason in the world why it would not work. The faster the wind blew, the more volume of oil would be pumped through the relief valve, and the whole system is pretty easy for do it yourself engineering with a minimal of parts.
I have also wondered too if there was a way a cavitation heating pump could be coupled to a windmill? I know on the battleships I used to build, the Navy said you could fry an egg on the rudder of the ship, because the cavitation of the water coming off the propeller just in front of it, made the steel so hot.
I do not have all the answers by any means, but I think a fair amount of BTU's could be generated just because the wind blows so often. It seems silly not to capture it, and use other means to heat water instead.