The achievement of high penetration of wind energy mainly in the Southern part of Europe but also in some regions in Central and Northern Europe is directly related to installing large capacity turbines in mountainous-complex terrain sites.

It is anticipated that nearly 25% of the 40 GW target for wind turbine installations in Europe by 2010 will be developed in such areas. In this connection the challenge for the European industry is twofold, namely to develop procedures which circumvent the barriers set to the transport and erection of MW-size machines in areas of limited infrastructure and to reduce costs by means of design optimisation and tailoring.

In the framework of the MEGAWIND project such procedures were formulated and applied to the design of a 1.3 MW prototype wind turbine for installation on a high wind speed complex terrain site. The conventional wind turbine design procedure was revised and adapted in the following four aspects:
Blade design: The geometry of the blade was optimised for maximum energy capture under high wind speed conditions. The structural design was carried out for a split-blade concept for a Class-I, IEC-61400-1 type blade of the MW scale.

Tower design and construction: New structural solutions were introduced for the tower by using advanced composite materials technology. The tower design features manufacturing and installation concepts based on the use of hybrid fiber reinforced plastic forming sandwich shells, adaptable to on-site assembly.

Gearbox and drive train: The entire drive train was specifically designed for high wind, high turbulent conditions aiming at developing a highly reliable, low cost, low weight geared drive system. Special attention was given to achieve very low noise emission.

Transport and erection: The introduced compact design concept (split-blades, on-site tower construction, light-weight components) facilitates machine transportation and installation under reduced infrastructure requirements.

The wind turbine design was conducted according to the IEC 61400-1 standard using state-of-the-art tools, extensively validated in complex terrain applications. Overall design assessment through systematic full-scale testing of each considered component, following MEASNET practice and the relevant IEC standards was performed. Test results were also used for the evaluation of the innovative features introduced in the wind energy systems, emphasising on the techno-economic issues.