Basically, power utility scale wind turbines turn slowly, whereas conventional generators operate at higher rpm, so that gear trains are used - putting extra weight at the tower top and introducing a source of shear damage in the gearboxes due to wind gusting and resulting inconsistent torque. For offshore wind farms, a big planning thing in Europe because of dense land use and because large-scale [noisy] units can be put where people don't live. Yet serviceability concerns offshore are greater, due to access costs, and that means getting around the gearbox SNAFU is key.
The question of who owns what property rights, and the use of papering a technology up with patents because they are allowable [Constitutional even] anticompetitive tools of wealthy multinationals, attaches to mature industries and the extreme patenting activity of wind energy technology these days shows the industry has matured beyond back-yard experimentation and first generation tax shelter promotions where the bugs became recognized and attended to. Indeed, in one California windy pass the wind farm had true "bugs" as a problem, insect hits by the blades causing them to load up with aerodynamic changes not unlike wing icing with aircraft.
In that regard, Anoka has its wind turbine across Hwy. 116 from the Rum River library, by the District 11 High School at 7th Ave - County Road 7. It is a joke. It was installed this summer and has yet to turn. A betting pool opportunity exists, what month, of what year, will the sorry thing first turn? That's a showing of a local venture's doing things on the cheap, buying obsolete junk from California wind farm locations, moving them to Minnesota, and claiming that's good faith compliance with requirements to invest in wind generation. Beyond that local digression, the PopSci item was interesting because of its opening reader comment, about - back to an earlier paragraph - intellectual property games large firms play:
Enercon's English-version homepage, here, has some browsing range, and the direct drive - permanent magnet solution is described, this link, including images from Enercon and a closing footer acknowledging the firm. See here, here, here, here, here, here, here, here, here, here, here, here, and here for more info. Strib carrying an AP feed of the Obama clean-energy-jobs theme.
________UPDATE________
Northern Power Systems, "Gearless is better," here; "the gearbox problem," here.