Windmills and Recording Studio [10] Click on image to enlarge.

Wind turbines are deceptive. There is something pleasing about the clean streamlines of the blades, the spindly looking tower, and the steady, seemingly slow rotation pumping out clean power (see figure above). But the size and expense of these mega-machines make them even more impressive. Anyone who has met the longest tractor-trailer rig they will probably ever see on the road in the USA can attest to the size of the blades, smoothly curved 35 to 50 meter long composites, streaming by in a convoy. The towers, while not as beautiful as the blades have a brutish power about them, requiring extra axles on the trailers that haul the steel beasts.

The rotation may seem slow, but that is an illusion of scale, while rotating at 20.4rpm [1], the tips of GE's 1.5MW wind turbines will be traveling at 82m/s, 184mph. Yes, the ends of those blades are going at NASCAR-level speeds. Remember centripetal force (=MV²/R) from physics? If you need a not so gentle reminder, search for "windmill explosion" on youtube.com to see the brutal real world physics.[7] Then there is the nacelle, where the tower connects to the energy collecting blades. This is where the linear power of the wind the blades transform to rotation is in turn transformed into electrical power. The nacelle contains the shafts, bearings, gearbox, generator, hydraulics, electrical controls, and mechanical controls for this standalone power plant (see figure below). It houses these in a school bus sized container 40 to 80 meters above the ground.

Wind Turbine Components [9] Click on image to enlarge.

Since the nacelle must be hoisted so high and the entire assembly moves to point into the wind, the nacelle components are chosen with the minimal weight to do the job, i.e. the "over-design" margins are as small as the designers dare. In total these rotating machines can cost in excess of $1 Million USD, a large investment in a machine typically located a significant distance from repair facilities and replacement parts. These machines have a 20+ year lifetime, so it is not a matter of if they will require maintenance, only a matter of when and how much. Their installation requires skilled people using a very large, very expensive crane.[8] Maintenance that requires the same operators and crane can also be very expensive.