World’s largest ferrite-based DD-PMG generator delivers excellent initial results

The new GreenSpur generator – which is believed to be capable of scaling up to multi-MW sizes and has been “modelled to 17 MW”, with no requirement for rare-earth magnets – was delivered to the UK Offshore Renewable Energy Catapult (ORE Catapult) Blyth test facility in early June. Initial testing has demonstrated an excellent correlation between expected results and the generator performance so far.

Further testing is ongoing, with preliminary analysis and results expected to be released at the start of Q4 this year.

The current system tests are being carried out on a 250 kW machine at the ORE Catapult’s refurbished and state-of-the-art testing facilities, as part of an Innovate UK funded project.

GreenSpur’s director of technology, Hugh-Peter Kelly commented: “Sophisticated computer programmes have been developed to model, understand and quantify the technology. Early results show close correlation to the outputs predicted by these programmes. This establishes confidence in the models and the predicted performance of larger systems.”

The ORE Catapult’s Test Facilities Director, Tony Quinn said: “We are pleased to have provided expertise and guidance for GreenSpur to develop their technology further, having already demonstrated a 75 kW version of the generator in our facility in 2017. This is a fantastic innovation, and a great example of a UK SME working with the ORE Catapult to develop new technologies.”

“GreenSpur’s new technology addresses major issues facing the next generation of DD- PMGs,” according to Andrew Hine, commercial director of GreenSpur. “The current generation of direct drive generators used in today’s offshore wind farms rely on rare earth magnets. It is very likely that the competition for magnet supply from other fast-growing industries, including defence, computing and electric vehicles, will significantly impact the supply of rare-earth magnets to the offshore wind sector.”

GreenSpur says its new technology is a “greener, cheaper and simpler alternative for the future of wind generation” and claims that “the radical new construction method solves many of the problems experienced by offshore wind turbines today, not least the need for large quantities of rare earth magnets. 

It has been estimated that a ‘conventional’ permanent magnet 10 MW wind turbine generator could use as much rare earth metal as 3000 electric vehicles.

Ferrite magnets are also significantly cheaper than rare earth ones, about £1 per kg vs £40 per kg.

Andrew Hine points out that rare earth magnet supply is dominated by China, and could be restricted as part of any escalation in US–China trade wars.

Andrew Hine also notes that “not only does our generator use no rare earth magnets, our source material – ferrite – is actually a waste product of the steel making process.”

The GreenSpur design also offers “rapid scaling” through a “unique modular design that enables generators to be constructed in stages, eg a 12 MW turbine can be “created by stacking 3x4 MW units in parallel.” The approach has even been described as opening the door to the 25 MW offshore wind turbine.