GreenSpur Wind is an innovative SME based in Middlesbrough, England. They aim to provide a sustainable alternative to offshore wind turbine generators by eliminating the requirement for Rare Earth materials. Specifically, the company has designed, developed and manufactured a unique permanent magnet generator. Rare Earth magnet materials have been replaced with a cheaper, widely available ferrite alternative and expensive copper windings have been switched to aluminium coils.
The innovative turbine generator developed by GreenSpur utilises an axial flux arrangement, where the magnets are positioned between the coils along the axis of the rotor. This is an alternative to the traditional radial flux generator layout, where the components are positioned around the circumference of the rotor. The team have chosen an axial layout to increase the interaction between magnets and coils via an enlarged surface area. Additionally, the modular design enables generator stacking, which allows multiple smaller stages that can be connected in parallel.
Since establishment in 2014, the company has produced various demonstration models based on its initial generator design. There are currently 11 international patent filings associated with GreenSpur’s Rare Earth-free generator. In July 2015, the company manufactured its first proof of concept unit, which was a three stage 2 kW model.
Following on from this, the company significantly scaled its next test unit, developing a 75 kW three stage model, supported by ORE Catapult. Generator testing was conducted in 2017 at ORE Catapult’s powertrain facility in Blyth, using the 1 MW test rig. Following these initial tests, the design was further developed using modelling and simulation techniques, such as electromagnetic FEA. Supported by the Warwick Manufacturing Group, the simulations have identified potential for maximising power output while reducing material cost and weight.
In 2019, the team returned to ORE Catapult’s powertrain facility to test a 250 kW pre-production unit. This unit was part of a four-stage 1 MW design. This development project was supported by a £1.25 m grant from Innovate UK. The 250k W trials produced positive results, which aligned with test predictions and previous test data.
In the autumn of 2021, GreenSpur returned once again to ORE Catapult to re-test its 250 kw unit. This testing was structured to run 10 different load cases across a range of speeds from 1 to 30 rpm. As a result, 300 data points were recorded, which were used to validate the accuracy of the Company’s electromagnetic FEA.
Following this successful re-testing, GreenSpur completed an initial 15 MW direct drive generator design. This was used to benchmark the generator against the National Renewable Energy Laboratory (NREL) 15 MW reference turbine. Supported by an Innovate UK grant, this new 15 MW generator design was reviewed by ORE Catapult. This review confirmed that GreenSpur’s 15 MW generator design is now able to meet the mass and efficiency targets required by the offshore wind market.
Following the 250 kW generator re-testing, the company set a focus on producing a design ready for market by the mid to late 2020s. Greenspur has estimated that a higher power design could reduce direct-drive generator capex by 33%, which provides a 5% reduction in the overall turbine cost. Since the retesting of the 250kW unit in 2021, and by introducing a new Rare Earth-free magnet from Niron Magnetics of the USA, GreenSpur’s new 15 MW design has been shown to reduce previous generator mass by 56%.
Due to the use of lower cost materials the generators could have a significant impact on LCoE. Further savings will also be made from the generator windings by replacing copper with aluminium.
Andrew Hine, Founder of GreenSpur Renewables, said:
“Scaling up short term production in the UK could create 200 new manufacturing jobs plus a further 70 in the supply chain. If the technology is deployed at the 2GW to 3GW level, it could lead to the creation of over 3,000 new UK jobs.”