Wind turbine
Wind turbine manufacturers design, test, manufacture, and assist with the operation and maintenance of wind turbines. Important choices facing them include turbine design (generator type, gearbox vs. gear-less, materials) and how much control to maintain over component supplies (internal vs. external). They must be concerned with maintaining their extensive fleets of operating turbines while at the same time developing newer and ever-larger models. The largest wind turbine manufacturers are based in Denmark, Germany, Spain, India, and USA.