GreenSpur Renewables is testing what it says is the world’s largest ferrite-based direct drive permanent magnet generator at the Offshore Renewable Energy (ORE) Catapult facility in Blyth, England.
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.”