Wind turbine blades made of wood – could energy become any greener than this? Blades made of UPM’s WISA plywood spin in windmills in the United States, among other countries. And there is more to come because a new component line has recently started up in Jyväskylä, Finland, just for this end use application.
Plywood is an amazing product that seems to suit just about any application. “A windmill is a bit of an extreme application for plywood, like the plywood used in the insulation boxes of liquefied natural gas carriers,” says the Business Manager of UPM’s plywood business, Jari Kosonen.
ONE BLADE IS A PUZZLE OF 2,000 PIECES
Globally, plywood blades remain a rarity in the windmill business. Wind turbine blades are usually made of pre-treated fibreglass, and to Kosonen’s knowledge, no one else manufactures plywood blades at the moment.
Plywood is the supporting part of a wind turbine blade. One 40-metre-long blade consists of almost 2,000 plywood components, which include about 100 different-shaped parts. The length of the parts varies from 10–15 centimetres to up to 3.6 metres. The blade is assembled at the customer’s factory by putting the plywood parts in a blade-shaped cast in a carefully prescribed order. Although the number of parts sounds enormous, less than six cubic metres of plywood is needed for one blade.
“Our customer is one of the world’s leading builders of windmills with approximately 30% of the global market. Big companies like to do business with other big players. For our customer, a wooden blade is a strategic choice and an alternative raw material. As a blade material, plywood is cheaper than fibreglass but, on the other hand, manufacturing plywood blades is more expensive,” Kosonen adds.
PLYWOOD IS LIGHT, STRONG AND RESISTANTA
UPM’s plywood components are used in 1.65 megawatt wind turbines. A windmill of this size generates electricity for about 30 blocks of flats. These types of wind farms are built inland.
Wind farms have to withstand many types of conditions; wind turbines spin on glaciers, on mountains and in deserts. According to Kosonen, the best qualities of birch plywood come into their own under rough conditions. “Birch plywood does not shrink and swell; it is light and, on the other hand, extremely strong in comparison with its weight. So far, not one single plywood blade has broken due to any failure in the plywood.”
Blade components are built at UPM’s mills in Lahti and now also in Jyväskylä, where a new line was opened in November 2008. “The growth prospects of wind power are fantastic, and that is why we want to be in this business,” Kosonen says.
Climate change has turned wind power demand into fierce growth. Between 2000 and 2006, the production of wind power quadrupled in the world, and its share of the world’s electricity production now stands at 1.3%. It is estimated that the growth will continue at a rate of about 20% per year. In 2007, about 3% of electricity was generated by wind power in Europe. Germany, the US and Spain are big producers of wind power.
Text: Tuovi Similä