Mr. Madsen, of Vestas, said that offshore turbines — less encumbered by roads and bridges — will keep growing more rapidly than their onshore counterparts.

Earlier this year, Vestas unveiled its plans for a seven-megawatt offshore machine, with a rotor diameter (the diameter of the area swept by the blades) of 164 meters. A March report, “Upwind: Design Limits and Solutions for Very Large Wind Turbines,” prepared with support from the European Commission, found that a 20-megawatt turbine — with each blade probably more than 120 meters long — was “feasible.”

But sheer size is not the only way that turbines will improve. Research and development work has proliferated around matters like how to pitch, or angle, the blades and how to monitor wind speed and direction at a turbine more accurately, using lasers.

“This is probably the most exciting time in the industry as far as companies launching new product platforms,” Mr. Radomski said, adding that much of the research and development work was happening in Europe, where the modern wind industry grew up.

Partly, he said, the flurry of development work is a result of the increasing number of manufacturers, which are looking for ways to differentiate themselves. Also, many of the best wind sites have already been claimed, and that has forced developers to build in places that are not quite so windy — making innovation all the more crucial for cost-effectiveness.

Wind turbines are complex machines. Each contains about 7,000 or more components, according to Tom Maves, deputy director for manufacturing and supply chain at the American Wind Energy Association. (That figure counts items like fasteners.)

In places like Texas, the U.S. wind-power leader, the turbines must withstand all kinds of weather extremes, from heat of 100 degrees Fahrenheit (38 Celsius) or more in the summer to frigid temperatures in the winter, along with occasional snow- or hailstorms.