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Of the three former wind-turbine suppliers Lagerwey, Nedwind and Windmaster, the latter two specialised in two-bladed fixed-speed wind technology. Nedwind was perhaps best known for a range of 500kW and 1MW models, characterised by either two or four 250kW generators. Windmaster's key product by contrast had for several years been a 750kW turbine model.

Despite the fact that both wind companies were frontrunners for the large sub-megawatt class models, their commercial success remained modest. One reason may simply be that local and international wind-market preferences had shifted in the early 1990s to three-bladed wind-turbine designs. Another is that successive Dutch government subsidy support schemes promoted development of wind turbine models with a rather high specific power rating (big generator, small rotor) and a small rotor, resulting in supplier and client adapting to chase the maximum subsidy.

The strong academic and research focus of the Dutch wind sector is also seen to have contributed to its demise, with many prototypes being developed but little high-volume commercially successful products.

Home market

The absence of adequate long-term support for developing a viable home market put Dutch companies at a disadvantage, particularly when compared to neighbouring German and Danish competitors.

Nedwind was sold to Danish firm NEG Micon (now Vestas) in 1998, just as the company was developing a promising new 1MW three-bladed turbine with an attractive design and, for that time, a large 66-metre diameter rotor. Sections of bankrupt Windmaster were taken over by Lagerwey the same year.

The company developed a two-bladed lightweight system introduced in 1986 with a blade mounting capable of pivoting, and passive pitch regulation - the 75kW LW 15/75. An 80kW model followed in 1988 and a 250kW version in 1993 based upon the same concept and design principles. More than 1,000 of these two-bladed turbines were sold locally and in foreign markets including Germany and India.

By 1996 Lagerwey had installed a prototype of a new 750kW direct-drive turbine with a single rotor bearing and an externally excited ring generator, developed in-house. Technical issues delayed commercial introduction and, according to insiders, most problems were only solved months before the company's bankruptcy in 2003.

Lagerwey did however become one of the world's first suppliers and leading partner in developing a commercial 1.5MW/2MW direct-drive turbine with permanent magnet generator (PMG), known as the Zephyros project, and many of its comprehensive products and wind-technology heritage are still alive.

Wind Energy Solutions or WES of the Netherlands is one technology offspring, which manufactures upgraded 80kW and 250kW models in increasing but still modest numbers.

The Lagerwey/Zephyros direct-drive technology has also been disseminated to three offspring companies, all in the Netherlands. Dutch Emergya Wind Technology (EWT) inherited the 750kW model, which has now been scaled up to 900kW. It has also developed 2MW and 3MW direct-drive PMG models for third-party manufacture. Darwind was founded in 2006 to develop a 5MW offshore direct-drive turbine based on the Zephyros concept. While XEMC of China took over the company in 2009, product development remained based in the Netherlands. STX “uåX˜äŠÊ˜·³Ç, based in the Netherlands but part of a large South Korean corporation, also develops, manufactures and markets direct-drive turbines locally based on Zephyros technology.

Lagerwey founder Henk Lagerwey and business partners started up a successor company called Lagerwey Wind in 2006, now a technology developer for third parties. Its first product was a 2MW direct-drive turbine with 82-metre rotor diameter with in-house developed passive air-cooled PMG, which was licensed to Global Wind Power of India. It is now working on bigger models.

Blade manufacturers

Rotorline, Aerpac and Polymarin dominated rotor blade manufacture. Rotorline at one stage was Nedwind's rotor blade manufacturing arm, than became independent and was acquired by LM Glasfiber (now LM “uåX˜äŠÊ˜·³Ç) in 1999. The renamed company ceased blade manufacture in the Netherlands in 2001. That year, Aerpac, the world's second-largest independent rotor-blade maker and technology leader, went bankrupt. Aerpac was probably the first in the world to introduce resin infusion moulding (RIM) vacuum technology on a large scale for its epoxy resin-based rotor blades, and currently a semi-standard manufacturing method.

Applying RIM technology meant a huge leap forward in achieving higher and more consistent product quality, as well as offering major improvements in working conditions, by minimising direct skin contact with epoxy resin, which can cause allergic skin reactions. Aerpac had also worked on APX-type rotor blade designs, production technology and moulds, which were sold, licensed and perhaps otherwise reused around the world. Several Aerpac offspring firms emerged, including Netherlands-based NGup, Composite Technology Centre and Suzlon subsidiary Aerotor Techniek. The last independent rotor-blade supplier in the Netherlands, Polymarin, finally closed its doors in 2009.

The recently founded company, Global Blade Technology (GBT) is part of the new breed of Dutch firms. GBT is a specialist in rotor-blade design, tooling and manufacturing technology. It conducts process and materials research, mould production and develops advanced blade manufacturing systems.

GBT is only one out of an increasing number of Dutch technology developers and engineering consultancies offering their expertise and services to international third-party clients. Many times this is conducted in close cooperation with technology institutes and higher education centres like Delft University of Technology and the energy research centre ECN. Direct-drive turbine technology, advanced rotor systems, modelling and design support are among some of the key areas of Dutch scientific and engineering sector expertise.

The only remaining Dutch-owned firm developing a large offshore turbine is 2-B Energy. Its 6MW concept incorporates a geared drive system, a two-bladed downwind rotor and a truss tower that extends right from the seabed to the nacelle bottom.

Renaissance

These successes indicate that the Dutch wind-power sector is gaining some strength. However, a weak point and perhaps an underestimated risk that could seriously hamper its growth is an incomplete supply chain. The Dutch market largely provides research, development, prototype engineering, building, testing and optimising. With a local manufacturing base virtually absent, there is a limit to green job-creation potential. And a limit to the learning opportunities through manufacture and assembly to transport logistics and installation, turbine maintenance, and ongoing staff and client feedback.

The still comprehensive Dutch knowledge base could regain a substantial manufacturing position in the world. Emerging wind-turbine manufacturing nations like the UK and South Korea show that it can be done with the right determination, sustained effort and adequate government support.