Wind energy: a technology that is still evolving

Wind energy is developing very rapidly and over 30 GW of capacity was installed worldwide in 2009. It is also continuing to mature, with rotor diameters and ratings steadily increasing. Now there are several commercial designs available with rotor diameters exceeding 100 m and ratings exceeding 5MW. Although the majority of developments are installed onshore, offshore wind is slowly taking off and there are plans for around 40 GW in Great Britain alone. The rapid growth has been accompanied by better understanding of the design issues, so that blades, towers, and other components are now lighter than they were 30 years ago and can be produced more efficiently. The most significant trend in recent years has been the move towards direct-drive generators, eliminating gearboxes that have, at times, been troublesome. Permanent magnet generators are delivering further weight savings, and research that is funded both by governments and manufacturers promises to deliver further improvements in cost effectiveness.