These are wind turbines at Altamount Pass, Livermore, California, USA. Google Map It is about one hour drive south east of San Francisco, right on the hills off the sides of highway 580. It is a splendid place, but kinda eerie. When i opened my car door, i heard a strange howling voice. I thought it's some kind of animal, until i got out i realized it's the sound of the wind. The winds are so gusty that i thought my car would be blown off the ground, then i realized my irrationality because i'd have to fly first before my car would. After 10 minutes, my ears start to hurt. As i later found out, the wind speed there is some 8 meters per second.
The turbines form lines scattered on the hilltops, scattered around a area of about 15 kilometers in diameter. Hundreds are visible from the highway. According to online info, there are over 4 thousands of them, being the world's largest wind farm in terms of number of turbines. There are at least 7 varieties of wind turbines visible, including one type that is vertical like a egg-beater. It is hard to get close to them, since there is no paved road leading to them, and the wind is too strong. There are many cows grazing on the field. I have only gotten close to one of the smallest type , which is about perhaps 10 meters high with turbine blade about 1.5 meters long. One can hear the blades whooshing by when underneath it. Some of them have cylindrical poles as their base, as opposed to metal struts. These are larger. Most photos are taken from a distance with a 8x-zoom camera.
Altamount Pass wind farm is built in 1981 and are continuously upgraded with turbines of various makes and technologies, some of which are experimental. There are more than 4 thousands of them, but all of them are of the smaller type. These wind turbines are rather old. Modern wind turbines are gigantic in size, typically some 80 meters high (20 stories building). As of 2010, some modern turbines is to be gradually installed to replace the old small ones.
Satellites view at Google Map shows that these windturbines are spread around a area that's about 15 km in diameter. For more info about Altamount Pass, see Wikipedia: Altamont Pass Wind Farm.