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Offshore Wind Journal

Sustainable wind needs a sustainable waste stream

Mon 12 Nov 2018 by David Foxwell

Sustainable wind needs a sustainable waste stream

David Foxwell reflects on the need to consider decommissioning when windfarms are designed, develop ways to handle what will one day be a huge volume of blade waste and recycle the rare-earths used in turbines.

The wind energy industry’s success will pose it some serious challenges if new windfarms and the technology used in them is not designed from the outset to be easy to decommission, can be repurposed, safely disposed of or the lifetime of assets extended.

Offshore windfarms are being proposed from Chile to Taiwan and from California to South Africa. There is little doubt that offshore wind will become a backbone of the energy sector in the next decade and that costs will continue to fall.

But how much will it cost to decommission offshore windfarms at the end of their useful lives and where will the pinch points in the waste handling stream arise?

Opinions differ about costs. As I’ve highlighted before, designing for decommissioning can undoubtedly reduce costs later, but are the multi-megawatt turbines on the drawing board now being designed for ease of disposal when the time comes? Will decommissioning be the only option? Some argue that the most cost-effective option – and most environmentally sound – would be to revise national and international regulations so that a range of end-of-life options could be considered, including extending asset lifetime.

The current approach to decommissioning is, effectively, to reverse engineer installation, which is expensive and requires bespoke equipment. As this potential decommissioning and waste disposal issue grows, environmental legislation is getting tighter, especially in Europe. It will only get more expensive if windfarm owners wait until the end of the lifetime of their assets to figure out how to do it.

I had a very interesting exchange of views recently with Morten Dallov Ibsen, a decommissioning and demolition manager at Niras. He believes there is still a tendency to plan for decommissioning in retrospect, missing the opportunity to optimise design and drive down the levelised cost of energy by minimising decom costs.

The waste stream from offshore wind will include concrete, steel, copper, aluminium, electronics, rare-earth metals and composites – a lot of composites. Vindeby, the only offshore windfarm to have been decommissioned to date produced 60 tonnes of composite waste alone.

Imagine how much greater the waste disposal challenge might be from 1-GW windfarm with 10-MW turbines. There are options, such as incineration, shredding and recycling into other products. Pyrolysis is another option, but how many of these processes are available at scale and could handle thousands of tonnes of waste brought ashore in a relatively short timescale? Processes have been developed that can recover glass fibre but are they cost-effective? Are there potential markets for recovered glass fibre?

Then there are rare-earth materials used in permanent magnets. Nd-Fe-B has become the ‘go to’ choice but the rare-earths on which European industries such as wind have come to depend are mainly mined in Asia.

Scientists at Fraunhofer IWES in Germany argue that a circular economy for end-of-life rare-earths and a recycling chain for rare-earth permanent magnets will be essential. As I noted here, direct drive generators are an increasingly widespread feature of offshore wind turbines as operators shy away from gearboxes, however the generators’ need for rare-earth magnets – which are mainly produced in China – means they are an expensive alternative, with the market effectively subject to a monopoly. This is something OEMS have already recognised.   

Mr Dallov Ibsen believes that waste treatment solutions for the composites in turbine blades clearly needs a lot of attention. “The wind energy industry should not only produce sustainable energy but sustainable waste materials,” he said.

He is absolutely right, and it can only ensure that it does so if it begins applying the limited recycling experience from the wind industry with that of other industries – of which there are number also facing issues with how to deal with composites – to the engineering and design phases of future windfarms.

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