Vinegar and epoxy resin: recycling wind turbine blades

Published On: January 19 2024

The UK has over 11,000 wind turbines currently in operation, capable of generating 30Gw (15GW onshore and 15GW offshore). In 2020, these turbines generated over 75,500 GWh of electricity, whilst accounts for just under 5% of our primary energy production.

However, as we’ve highlighted before in previous articles on load cells and wind turbines, there is a problem. Whilst the steel towers and components inside a wind turbine can be recycled, the massive turbine blades are not recyclable – at least, not at scale. That becomes a major waste problem waiting to happen; by 2050, there could be up to 42million tonnes of redundant blades worldwide.

 

The story so far

Some recycling initiatives have been successfully implemented:

  • Old blades can be shredded into tiny pieces which can be used as fuel and added to cement to strengthen it, bit it is labour intensive and limited in scope.
  • More innovative projects have sought to reuse whole blades (or substantial parts of them) in architectural projects, from pedestrian bridges to bike sheds, and even building cladding. (See our blog on turbine blade bridges)

However, the goal has always been to break down the blades back into their component elements to be recovered and reused. Two projects have taken two different approaches to solving the issue

  • Making new blades that can be broken down using acetic acid
  • Breaking down existing blades using chemical that “chew through” the epoxy resin binding the fibreglass blades together

 

Pass the vinegar

Wind turbine giants Siemens Gamesa are already producing new RecyclableBlade turbine blades that can be recycled at the end of their lifespan. The first 81-meter long RecyclableBlades were manufactured in 2021 at the Siemens Gamesa factory in Aalborg, Denmark.

As the company explains:

“(These) wind turbine blades are made from a combination of materials cast together with resin to form a strong and flexible lightweight structure. The chemical structure of this new resin type makes it possible to efficiently separate the resin from the other components at end of the blade’s working life. This mild process protects the properties of the materials in the blade, in contrast to other existing ways of recycling conventional wind turbine blades. The materials can then be reused in new applications after separation.”

The “mild process” involves soaking cut-up sections of the blades in mild acetic acid heated to 80degreesC for a few hours. As one of the company’s engineers demonstrated in a recent edition of the BBC technology show.

See the programme here.

And yes, that’s basically a vinegar bath that causes the epoxy resin to loosen. The glass fibre layers just peel apart, and can be recovered for other manufacturing uses including suitcases, furniture, surf boards and other consumer goods.

 

Breaking it all down

Meantime, at Aarhus University in Denmark, a team have discovered a chemical process that does much the same for old blades. In a paper for the journal “Nature” by researchers at Aarhus University and the Danish Technological Institute:

“The researchers have shown that by using a ruthenium-based catalyst and the solvents isopropanol and toluene, they can separate the epoxy matrix and release one of the epoxy polymer’s original building blocks, bisphenol A (BPA), and fully intact glass fibres in a single process.”

This could be a real game changer, as Lisa Ekstrand, Vice President and Head of Sustainability at wind energy company Vestas explained:

“We can now view old epoxy-based blades as a source of raw material. Once this new technology is implemented at scale, legacy blade material currently sitting in landfill, as well as blade material in active windfarms, can be disassembled, and re-used. This signals a new era for the wind industry, and accelerates our journey towards achieving circularity.”

 

More load cell and turbine stories to enjoy

Check out a couple of our other wind turbine articles:

 

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