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.
There is a huge international demand for Rare Earth magnets with approximately 90% of global production based in China. A 2019 study into Rare Earth material demand showed the permanent magnet sector had the highest demand, requiring 38% of the materials. The GreenSpur generator could prevent Rare Earth supply bottlenecks by significantly reducing demand within the offshore wind industry.
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 has 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.
The Journey with ORE Catapult
Since the company was established in 2014, GreenSpur has produced a number of 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.
The company significantly scaled its next test unit, developing a 75 kW three stage model, with support from 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 (fine element analysis). Supported by the Warwick Manufacturing Group, these simulations have identified potential for maximising power output while reducing material cost and weight. There are currently 11 inventions covered by 51 patent assets internationally (33 patents granted) associated with GreenSpur.
In 2019, the team returned to ORE Catapult’s powertrain facility to test a 250 kW pre-production unit – 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 again returned to ORE Catapult to re-test its 250 kw unit – with re-testing sponsored by Hitachi Metals Europe via the EU MaRINET2 Test Programme. 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, with these 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 which 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. The 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.
Impact
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, these generators could have a significant impact on LCoE (levelised cost of electricity). Further savings will also be made from the generator windings by replacing copper with aluminium.
Environmental benefits
GreenSpur’s Rare-Earth free generator does not involve the creation of tailings – large volumes of waste material associated with the mining process for Rare Earth materials which can include processing chemicals, acids and radioactive materials. For each tonne of Rare Earth materials produced, approximately 2,000 tonnes of tailings are generated.
These waste materials can also impact surrounding areas and communities due to wastewater contamination. The ability to manufacture wind turbine generators with no reliance on Rare Earth materials – and therefore free from traditional mining and refining processes – could deliver positive environmental benefits.
Additionally, utilising these Rare Earth-free magnets on a larger scale could create a circular manufacturing process making use of a product previously designated as waste, delivering the opportunity to create a high-growth supply chain.
Next steps
As the company continues to grow and develop larger generators, support from industry will be crucial for a successful commercialisation process. To that end, GreenSpur has started to build a network of industry bodies – including ORE Catapult, Warwick Manufacturing Group, DNV GL, Ricardo Engineering and the Manufacturing Technology Centre (MTC) – to accelerate the company’s transition from R&D to market ready product.
Though scaling manufacturing capability with a rapidly progressing technology can prove challenging, large scale adoption of a Rare Earth-free design could eliminate key material supply chain bottlenecks. GreenSpur will need to continue supporting the development of simulated models with physical testing and validation while also considering commercial factors such physical product manufacturing or the legal processes associated with licensing designs to third party manufacturers.
A key objective will involve demonstrating effectiveness of the technology on a larger scale when compared against conventional Rare Earth generator designs, and will include overcoming potential apprehension among OEMs who have invested heavily in existing generator technology.
The company estimates that successful scaling to deliver the Rare Earth-free generator at the 2 – 3 GW level could create more than 3,000 UK jobs in supply chain and manufacturing. The GreenSpur team expects to see a move across the megawatt wind industry towards axial flux, and are positioning themselves to become a key player delivering new and commercially viable permanent magnet generator technology of benefit to the wider wind energy sector.
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.”