Spanish no axis wind generator

A concept being promoted as a possible alternative to horizontal axis turbine technology has found a small foothold in the Spanish market with the grid connection of what is described as a "no axis wind turbine" at Hozalla in Castille and León. The technology, Wind Energy Converter No Axis (WECNA), has been developed over five years by Enerlim, a Basque research and development firm.

The 300 kW unit consists of three parallel cables looping around two 24 metre-high tripods which are placed 135 metres apart. Each cable passes through one of three generators fixed to one or both tripods. A series of plane, slim and semi-transparent blades (11.5 metres by 25 centimetres) are attached vertically to the cables. Wind drives the blades, forcing the cables to move through the generators. Pitch control and limitation operate automatically via the blades' inherent aerodynamics, orienting them to receive optimum winds at 3.5 m/s.

The system has three main advantages, according to Enerlim's Inaki Garaio. One is price, estimated to be in the order of ESP 100,000 (EUR 600) per kW installed. Another is the fact that it is made up of a series of readily available components widely used in other fields. And it is highly adaptable. "Extending installed capacity is simply a case of joining up another unit horizontally, in the same way that one train carriage is joined to another," Garaio says. The system may also be extended vertically with a "curtain" of blades installed above another and it could be applied in this way across valleys and canyons. Furthermore, the blades travel at a maximum of 40 kilometres an hour -- six times slower than the tips of larger horizontal axis wind turbine blades -- thus reducing the risk of collision with birds, according to Garaio.

The prototype has been installed by a small newcomer to the wind industry, Ecoeolica, with an investment of ESP 30 million. Seven more developers plan to install the system, Garaio claims. Enerlim is also negotiating for at least one prototype of between 900 kW and 1.2 MW, which involves a vertical extension of two complete sets of blade curtains. In response to demand, the four manufacturers behind WECNA components have formed a new company, New Energy for a Cleaner Environment SA, for large scale manufacture.

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