The UK company said the 250kW technology has no requirement for rare-earth magnets and uses a new construction method that solves several problems currently experienced by offshore wind turbines. 


Testing will be carried out over the next few months, supported by a £1.25m grant from Innovate UK.  

GreenSpur said replacing scarce and expensive rare earth magnets – £40.00 per kilogram – with cheap and abundant ferrite magnets (£1.00/kg) could deliver generator CAPEX saving of around 33%. 


It added that rapid scaling is possible through a modular design that enables generators to be constructed in stages – for example a 12MW turbine can be created by stacking three 4MW units in parallel. 


A 75kW generator was tested at Blyth in 2017, after which an agreement was signed with ORE Catapult and Warwick Manufacturing Group to build a single-stage 250kW direct drive generator as part of a four-stage 1MW design. 


GreenSpur commercial director Andrew Hine said: “GreenSpur’s new technology addresses major issues facing the next generation of DD-PMGs. 


“The current generation of direct drive generators used in today’s offshore wind farms rely on rare-earth magnets. 


“Not only is the supply of these dominated by China – and may possibly be restricted as part of the ongoing US-China trade war – there is also competition for magnet supply from other fast-growing industries, including defence, computing and electric vehicles. 


“While a mobile phone only uses a tiny amount of rare earths, each large-scale DD-PMG generator may use several tonnes – and commodity prices have now started rising again. 


“Not only does our generator use no rare earth magnets, our source material – ferrite – is actually a waste product of the steel making process – unlike rare earths, whose mining is environmentally damaging.”

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