From wind power to sugar rush – recycling comes full circle

They all share carbon, and they have all derived from the same wind turbine blade – putting a whole new spin on the circular economy.

Dr John Dorgan, Professor of Chemical Engineering and Materials Science at Michigan State University, led a research team who began their journey of looking at the recyclability of wind turbines, by starting with the end of their life in mind.

Wind turbines are a well-regarded means of renewable energy, and they must be strong and durable to work. In fact, the bigger the blade, the better the return on energy, which means that many turbine blades do not reach the end of their useful life before being changed for larger ones. Also, the mechanical part oftentimes outlives the blades. The result, an early end-of-life turbine blade, and a massive landfill problem.

The cost of recycling

Sadly, the cost of sending these blades to landfill is much cheaper than it is to recycle them, as a result, it is estimated that by 2050 the culminative blade waste going to landfill will be approximately 2.2 million tonnes.

On speaking about the current standards of recycling versus landfill, Dorgan said: “The main problem is, it’s simply uneconomic to do it. It’s cheaper to just bury it in the ground than it is to reprocess it into something useful.”

Dorgan has a history working with PLA – polylactides – which has its original applications in biodegradable and sustainable packaging. It can also be used as a fibre for making textiles and clothing. So, when he started to look at how to make wind turbines more energy efficient, Dorgan said it was “a natural evolution for me to think about how could PLA potentially be used in this application”.

The holy grail of the circular economy

The application of the composite resin for the blades, which is made up of a mixture of glass fibres with a plant derived polymer and a synthetic one, enables the resin to be strong and durable enough to make turbine blades, but crucially, once they reach the end of their life, the material can be dissolved in a polymer and made into a multitude of other goodies, this is because they all share the carbon commonality.

This means that the turbine blades could be reused in an infinite loop, seeing a return on the investment of recycling them, and enabling them to be truly circular.

Here are just some of the items that the recycled turbine blades can be turned into:

• New turbine blades
• Chewy sweets – such as Gummy Bears
• Energy drinks
• The absorbent component of nappies
• Car headlights
• Plastic casing for technology, such as laptops and computers

How does it work?

“So, the holy grail in polymer recycling is always to go from the same application back to the same application.” And with the resin material the team have developed, they can upcycle, down cycle, or recycle the material to use in a multitude of applications.

The team found that by “shredding” the panels and adding more polymer, they could use injection moulding to make low-value items such as plastic housing for computers.

They could also make new turbine blades, which have the same properties as non-recycled blades. They did this by soaking the blades in an MMA monomer, which dissolved the hardened resin. They then removed the glass fibres and the left over “syrup” was used to make more blades.

But the most appealing potential of recycling them was turning them into something of high value. By testing various chemical reactions, the team were able to produce plexiglass.

Heating the resin to a high temperature also enabled the team to produce poly(methacrylic acid) which is an absorbent material found in nappies.

And, amazingly, the team were also able to produce potassium lactate – which is added to food as a preservative. Dorgan used this to make his own gummy bears – which he ate.

Molecular flexibility

“I think the idea of molecular flexibility, being able to move carbon from one type of carbon to another type of carbon is perhaps the big idea here,” said Dorgan.

So, next time you happen to walk or drive past a wind turbine farm, just think that one day in the future, you could be using the blades in your home … or eating them!