United Kingdom

United Kingdom

'Iron-based 10MW generator possible'

UK: The new chairman of electromagnetic engineers GreenSpur Renewables believes the company's plans for an up-to 10MW generator could disrupt manufacturers' preference for rare-earth elements (REEs).

Andrew Hall left Siemens Gamesa in October 2017
Andrew Hall left Siemens Gamesa in October 2017

GreenSpur previously developed the "world’s first ferrite-based direct-drive permanent magnet generator" capable of multi-MW generation.

Next year it will assess the thermo-mechanical performance of the first stage of an up-to 10MW generator at an ORE Catapult facility, testing this against its own computer modelling.

This could eventually enable actual construction of the 10MW generator.

After type-testing, certification, and formally approaching potential customers, the 10MW machine could be online in "two-to-three years", according to the company’s new chairman Andrew Hall.

The former chief financial officer at Siemens Gamesa joined the UK-based company in October.

By only using iron-based magnets, Greenspur hopes to remove a reliance on REEs — traditionally the magnet material of choice for wind turbines, and increasingly electric vehicles (EVs) and other batteries.

The case against REE

Extracting REEs from surrounding deposits can cause serious pollution, and can be an energy- and water- intensive process.

REEs also face significant price volatility as demand rises for EVs and battery storage. This will be explored in Windpower Monthly's December issue.  

"When you look at the future demand for other industries, we are going to increase our demand for rare-earth metals from battery suppliers.

"Long-term, there will continue to be shortages and significant price volatility," Hall told Windpower Monthly.

As demand rises, some companies opt to ramp-up production to better match supply and demand, while some turbine manufacturers and researchers have looked at recycling permanent magnets.

Some companies aim to use less REEs, and others try to find alternatives, removing the need for using rare-earths altogether. GreenSpur is firmly within this fourth group.

"It’s essential that the wind industry, in order to achieve an LCOE (levelised cost of energy) at parity or below grid parity, that they are able to reduce their costs.

"Our generator has similar performance (to REEs), but at a significantly lower cost," Hall added.

The ferrite-based magnets the UK manufacturer uses in its generators are traditionally about a third as powerful as neodymium-iron-boron magnets.

The case for iron

However, GreenSpur’s axial-flux design — in which flux is produced along the axis of the rotor as opposed to around the outside of it — makes generators just as powerful as REE-based generators, Hall claimed.

"The innovation of GreenSpur is how we construct a wind generator and optimise the flux density over your conducting coils," he explained.

"That way, we are able to produce similar levels of power to REEs."

Iron is cheaper, widely available to source and does not suffer the price volatility that REEs do, he added.

Iron-based magnets can also operate at higher temperatures, meaning cooling is not as critical, Hall pointed out. Meanwhile, REEs can be demagnetised in these conditions.

GreenSpur is currently in the prototype phase of development, using computer modelling to assess performance of its generator.

Computer modelling has so far supported GreenSpur’s hypotheses, boosted confidence confirming to them that scaling up to 10MW is possible.

Hall said so far GreenSpur had not seen any significant differences between the performance of ferrite-magnet generators and those using rare-earth metals.

"What we have seen over the various prototypes we have built is that the efficiency is very similar between compute models and real-world performance," Hall added.

"We know what we are doing in terms of scaling up. We see now that it is possible to build a 10MW generator."

Commercialisation

GreenSpur is in talks with unspecified OEMs. They also share GreenSpur’s concerns about rare-earth shortages and price volatility, Hall added.

Overall, he believed GreenSpur’s technology is "sufficiently advantageous" — particularly at over 10MW — that the company can persuade some manufacturers to buy the complete generator.

"There is not a trend one way or the other for OEMs having their own generators or having to source their own components," Hall said.

"But this is only the case as long as there is no disruptive technology.

"I think we have a generator that would disrupt that significantly and we could convince OEMs to change their process and buy a complete generator."

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