One of the coolest things about this video from Deutsche Welle is the thought that giant wind turbines have been in operation long enough to need overhauling. The industry is truly maturing as it continues to show mindblowing growth.But the best part of this video is a little more visceral: Look at how massive that gearbox is! Or check out that hydraulic wrench, which I find endlessly fascinating. (Your own experience may vary.) All those metal shards in the gear oil looks expensive, and it is: a technician says in the video that a turbine overhaul costs about two-thirds the price of a new turbine, which in this case run up to 200,000 euros a pop.Wind turbine transmissions are crucial in connecting the turbine blades, whose speed (and thus power potential) changes over time, to generators. In some cases, transmissions use planetary gears to reduce the amount of torque delivered directly to a generator to increase efficiency and reliability. In others, transmissions can distribute torque across an array of generators based on available load. (For more on wind turbine transmissions than you may ever need, read this paper.)Still, as you can see, adding an extra layer of gears in between the massive turbine blades and costly generators only increases expenses. Recently, direct-drive turbines have become more common, and quite possibly are the turbines of the future. But for now, 15 ton gearboxes are still in use, which means we all get to enjoy some awesome machine porn.@derektmead