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Offshore Wind Journal

Offshore Wind Journal

Academics to industry: we need to talk about rare-earths

Tue 02 Apr 2019 by David Foxwell

Academics to industry: we need to talk about rare-earths

David Foxwell reflects on what wind energy's growth might mean for demand for rare-earths and the industry’s growing dependence on them

Last week, at the company’s AGM, Siemens Gamesa Renewable Energy’s chief executive Markus Tacke said he sees good times ahead, with offshore wind playing a key role in future growth at the company.

With the industry still in its beginning, he said, Mr Tacke expects offshore wind to play a pivotal role in a wave of growth that will hit double digits. Measured in market installations, Siemens Gamesa sees growth of more than 27% annually between now and 2025, largely driven by new offshore markets, including Taiwan and the US.

Fast growth in the US market and throughout the wind energy industry is to be welcomed, but the supply of certain types of rare-earth metals – notably neodymium – are critical for offshore wind power and their supply is potentially problematic. Perhaps not right now, but in the not too distant future.

Direct drive generators are an increasingly widespread feature of offshore wind turbines, as I noted in an article about GreenSpur Renewables development of a ferrite-based direct drive permanent magnet motor. However, the rare-earths for the magnets in the motors means they are a potentially expensive alternative, with the market effectively subject to a monopoly.

Research into the material requirements of future energy systems has been growing in recent years, but there are still many unknowns. 

A recent paper in the journal Nature Sustainability looking at the way the industry increasingly depends on a supply of neodymium, Impact of the establishment of US offshore wind power on neodymium flows, by Tomer Fishman and T E Graedel, involved simulations of the future flows and accumulation of thousands of tonnes of neodymium in offshore turbines.

As the researchers pointed out, the permanent magnet housed in a turbine’s nacelle weighs around 4 tonnes, over 25% of which is neodymium. “In other words, there’s neodymium the weight of a car in each of these turbines,” they said.

“If an ambitious scenario like the Department of Energy’s Wind Vision is to materialise, our study suggests that as many as 15,000 car-weights worth of neodymium would be required by 2050, even with technological improvements to reduce neodymium content,” they wrote.

This requirement is far from trivial. Current neodymium production and supply chains involve economic, environmental, and geopolitical challenges and much greater understanding of the production and reuse potential or rare-earths – which are also used in plenty of other industries – is required.

“Incorporating material flow and stock analysis, especially of specialty metals and ‘critical materials’ into energy planning would be prudent and support forward-thinking planning for reuse, the authors of the study said.

Although it’s not an issue yet, constrained supply of rare-earth metals required for large offshore wind turbines seems increasingly likely. It is possible that supply chains for rare-earths could exert constraints on the growth of offshore wind and other rare-earth-metal applications in coming years.

The study in Nature Sustainability found that more than 15.5 Gg (15.5 kt) of neodymium would be required by the US offshore wind industry by 2050. Remember, that’s just the US market, and doesn’t take into account competition for materials from other fast-growing industries, including defence, computing and electric vehicles. Added to that, extracting and processing the metals is environmentally damaging.

The good news is that demand could be reduced by up to 20% by circular usage from decommissioned turbines, but only if recycling technology is developed. Or, better still, I’d argue, if the magnets used in turbines are designed not only to use smaller amounts of rare-earths but are also designed from the outset to be reused.

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