On the other other hand they seem mechanically simpler because the entire turbine doesn't have to be mounted to pivot depending on the direction of the wind, and the column that holds up the turbine and blades is much shorter.
I think we can make some conclusions about the power output for a given material input. Based on the the images, my assumptions are: 100m mast and 80m blades; for the vertical turbines, a radius of 50m. The blades look to be lighter weight, but the mast looks heaver weight, so say the two styles use similar amounts of materials. Also, windspeed is logarithmic with height.
Wind power goes as the cube of wind velocity over the swept area. With my assumptions, the vertical turbine outputs about 2.7MW, while the horizontal turbine outputs about 8.4MW. The reason is height: it helps to have the blades sweep more higher altitudes wind, where it's faster.
These might be easier to pack tightly into a windfarm, where the metric that matters is W/m^2. But most of us care about W/kg because that is proportional to W/$: the winner looks to be horizontal turbines because they reach higher.
A hybrid of horizontal behind vertical might be interesting. There are diminishing returns to how "deep" you can make your windfarm: the trailing edge suffers from turbulence from leading edge, and these could work better in turbulence.
Sometimes they are idle not because of the lack of wind, but because of the lack of need for the electricity. When power demand is low, the wind turbines are the first things to be stopped. In fact, they use an electrical braking system to keep them from turning. The power companies say that it is much easier to stop/start wind turbines than lower/raise the output of gas/nuclear/coal power plants.
> When the wind is not in a favorable direction the turbines are idle.
>Why would they be idle? They can pivot for a reason
It seems to me you are reading into the post something not there. The person I replied to, quoted above, did not ask what you asked, and actually stipulated that HAWTs do pivot to turn into the more favorable direction.
Suppose the wind shifts to the east, enfilading all those miles of turbines. It’s a turbulence nightmare. But fortunately a rare event. An edge case where idling makes sense and staying online doesn’t.
At the extremes of nacelle yaw, the upwind turbines may cast a wind shadow on a downwind bank. Again an edge case where idling some turbines is a reasonable tradeoff.
These are networked smart devices. And humans in the loop monitoring and tweaking.
This is pretty consistent with my loose understanding of how these winds work and my experience in south east Australia: the predominant wind directions vary very significantly by season, and even within seasons substantial deviation is much more common than people often think.
The Llano is the southern end of the High Plains that extend all the way into Montana. As it passes the Rockies the Jet Stream tends to bend south. Further east the weather is more varied.
Or to put it another way, its a fair bet people settled in Amarillo for its less horrible weather. There’s not a major city between it and the Rio Grande at Albuquerque 450km to the west just some small towns here and there mostly where the railroad did something interesting.
The Llano and the high plains weather patterns are dominated by macro scale climate patterns. This is why the large wind farms are there.