Fair winds for polymers
Full sail ahead for wind power thanks to composites
The composites industry has proudly taken up the challenge in the race for power in the wind energy industry. The development of epoxy or polyester resins, foams and fibres adapted to new processes, such as resin transfer moulding (RTM), has enabled manufacturers to create blades of over 70 metres which are able to power 7 or 8 MW generators. Although constant increases in size have been heavily criticised, technical limitations have not yet been reached in this regard, although caution is advised. Germany, for instance, has "re-powering" programmes that replace old wind turbines with fewer but more powerful turbines. Experts say that, come 2034, around 235,000 tonnes of materials used to build the blades will have to be recycled every year throughout the world.
This is why manufacturers are already focusing their efforts on creating thermoplastic polymer matrices which are easier to recycle than thermosetting resins. In this respect, polyamides and acrylics in particular are taking the world by storm. They will make it easier to repair very delicate, and therefore very expensive, blades.
A new life thanks to plastics
What if the future of wind power was not just a matter of size? It is a sign of the times that innovation is increasingly focused on wind power projects that are more in line with the current trend of energy harvesting. This approach involves having smaller facilities and providing local wind power to meet the wind power needs in regions that do not have large capacity energy transmission networks. With this perspective, the Swiss company Bogga Wind Power developed a vertical elliptical wind turbine with three composite blades. The turbine is 100 metres tall and only 35 metres wide; although it produces barely over one megawatt (MW), it generates less turbulence than a traditional wind turbine of equal power, and its footprint is only half that of an old wind turbine!
Smaller yet, but nevertheless original in its own right, the vertical wind turbine developed by the French engineers at VoileO works with twelve PVC jibs pivoting around a 12 metre mast. With its 200 sqm of rigging, it only produces 75 kW but has the distinct advantage of not requiring authorisation due to its low height.
Full of energy and creativity
The idea of creating vertical wind turbines to produce electricity locally has captured the imagination of many and discouraged many others. The main difficulty resides in the fact that they have to run at a constant rate although they are subject to irregular wind speeds. To solve this problem, the Vertéole company based in the Rhône-Alpes region, which manufactures 500 W to 20 kW wind turbines intended for use in urban or rural settings, opted for a system based on variable geometry. Its latest spherical turbine combines a generator made from magnetised composites with rigid petals moulded from a very resistant resin which can fold back in on themselves when the wind is blowing too hard..
Travel writer Jérôme Michaud-Larivière decided to put down his suitcase to plant wind trees. The new type of fuel he developed with a dozen enthusiastic people within his NewWind company has enabled ingenious biomimetic wind turbines, christened AeroLeaf, to be "grown". Each of these ABS plastic microturbines was designed to make the most of any type of wind, whether turbulent or laminar, in natural or built-up environments. Arranged in the form of wind trees, these light vertical wind turbines produce around 3 kW of uninterrupted and silent power. They can also be set up in various configurations, daisy-chained on a façade or a fence.