#wyoming

Returning wind turbines to Mother Nature

Don’t ask questions. Renewables are there to save the planet. Period. Including wind. That is until decommissioned. In Wyoming, Casper Solid Waste Manager, Cynthia Langston, said that though most turbine blades can be reused, there are some that are simply un-recyclable. So 900 blades are headed for landfill.

Langston said, “These blades are really big, and they take up a lot of airspace, and our unlined area is very, very large, and it’s going to last hundreds of years.”

Fibreglass can be ground down into fine particles. Although there is a lot of work to cut up 80m wind turbine blades to be able to be fed into a grinder.

Blades can be incinerated but fibreglass contains only 25%~30% organic material, so its heat content is low, and its ash content is high. The ash is primarily calcium oxide, which comes from the calcium carbonate, boron, and other oxides in the glass. That heads straight to landfill.

Pyrolysis is the process of chemically decomposing or transforming a material into one or several recoverable substances by heating it to very high temperatures in an oxygen-depleted environment. Pyrolysis is different from incineration, which takes place in an open atmosphere.

Pyrolyzed fibreglass decomposes into three recoverable substances: pyro-gas, pyro-oil, and solid byproduct— all of which can be recycled. In the US, auto tyres are treated this way. However in order to put blades into a pyrolysis reactor, they must be shredded into 2″ pieces (a lot from one 80 metre blade). At about 5000F, the hydrocarbons in the resin decompose into gas. The gas is drawn off and sent through a scrubber, which separates it into pyro-gas and pyro-oil. The pyrogas is very clean and has an energy content similar to natural gas.

In Germany cement maker Holcim is using the polyesters coming from crushed turbine blades for use in cement. Recycling 1000 tonnes of fibreglass material in cement manufacture saves up to 450 tonnes of coal, 200 tonnes of chalk, 200 tonnes of sand and 150 tonnes of aluminium oxide.

Wyoming could theoretically follow the lead of Holcim but presumably, the cost to recycle fibreglass turbines is way more expensive than to bury them.