What Happens at the End of a Wind Turbine’s Use?

I have often been asked by members of the public what happens to wind turbines at the end of their lives. For many of the components, that’s easy. Steel, copper and aluminum have well established scrap markets – the vast majority of the turbine is worth money. But what about the blades, usually made of a fiberglass composite material, and the nacelle housing? Today’s wind turbine blades weigh 6-7 tonnes each.

Of course in Ontario we are a long way from decommissioning turbines. A turbine usually has a 20 year design life, and as recently as 2000, there was only one commercial scale turbine in operation in the province. But it is a different story in Europe. Denmark and Germany have been using wind turbines in large numbers since the 1980’s, with a big surge in the 1990’s. Of course earlier models were smaller, and might have a 12 m blade instead of today’s 40-45 m blade. But still, there are a lot of turbines that will be coming down due to age. In most cases, the site is repowered, with a few large turbines replacing a lot of small ones, usually doubling or tripling the output.

In Germany, a cement firm has experimented with using the turbine blades as fuel to make cement. The resin in turbine blades has very high energy content, so a tonne of blade replaces more than 500 kg of coal. The high temperature in cement kilns ensure no residues. The silica in the glass fibers found in the blades forms part of the cement, substituting for sand that is normally added.

The blades are cut up at the turbine site using a special wire saw into 10 m long sections that can travel on conventional trucks. At the factory, the pieces are shredded, and then fed into the kiln. The factory cost 5 million Euros to build – this is at the early commercial stage, and beyond the lab.

Of course, other composite products could contribute to the mix. One could imagine everything from RV’s, to boats, to skis, snowboards and tennis rackets finding its way into the cement kiln, rather than the landfill. Cars are using an increasing amount of composite materials as well, due to its light weight.

Ontario has a vibrant cement industry. Perhaps in a couple of decades they will have a new fuel source too.

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