Bigger wind turbines generate more power, but you can get just as much power by using a bunch of smaller wind turbines. The question is, which way do you go if you want to produce more power while staying as environmentally friendly as possible? We totally gave it away in the hed, but the scaling is such that truly gigantic turbines are an inevitability.
The largest operational wind turbine in the world currently produces 7.5 megawatts of electricity with a blade diameter of about 400 feet. This isn't exactly small, but the EU is planning for a new offshore turbine with a blade diameter of 800 feet that can produce twenty megawatts of power while spinning at six RPM. Here's a handy little diagram that compares the size of that wind turbine with the wingspan of an Airbus A380:
Big turbines aren't just awesome, it turns out that is substantially more efficient to go big. By scaling just the size of a turbine, you can also increase how environmentally friendly it is: every doubling in size results in a 14% decrease in cumulative emissions per kilowatt. And there's no reason to stop at 800 feet diameters: new techniques that can substantially reduce the loading on large turbine blades makes creating individual blades that are 500 meters long (or more) a real possibility.