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Improved magnets for energy generation through advanced tidal technology

Final Report Summary - MAGNETIDE (Improved magnets for energy generation through advanced tidal technology)

Executive Summary:
MAGNETIDE is a collaborative applied research project funded by the 7th Framework Programme (FP7) of the European Union. The project consortium is made up of three small-to-medium enterprises (SMEs) and four research and technology development organisations (RTOs). MAGNETIDE is led by ATARD, an advanced engineering company based in Turkey that is well placed to benefit from this technology.
Due to regulatory drivers and environmental concerns, renewable and sustainable energy sources are high on the global agenda, and tidal energy is one of the forms of renewable energy that is being explored. Tides, unlike waves and wind, can be predicted. It is this predictability that makes tidal energy such a valuable resource. This is particularly so in Europe, as it has a high tidal energy potential, with some of the largest tidal flows in the world, e.g. the Atlantic-facing coasts of the UK, France, Spain and the North Sea. Combining this with Europe’s advanced research and development in ocean energy capture systems, a major potential for ocean energy extraction exists. Tidal stream resources are generally largest in areas where a good tidal range exists, and where the speed of the currents are amplified by the funnelling effect of the local coastline and seabed, for example, in narrow straits and inlets, around headlands, and in channels between islands.

Project Context and Objectives:
Tidal Sails, one of the SME partners in MAGNETIDE, is developing a highly competitive and efficient tidal energy generator. One of the key characteristics of tidal energy capture systems is that they deliver large but locally fluctuating output torque and rotational speeds, leading to poor sustained reliability of generator gearboxes. The torque transfer requirements are demanding and gearboxes are complex, expensive to manufacture and not compact. Repair, renewal and maintenance of any failed components often require the gearbox to be brought ashore: a time-consuming and expensive operation. Larger and more complex gearboxes typically require pressured lubricating oil systems with a large oil reservoir. Any mechanical failure can result in leaks of lubricating oil into the water. Even under ideal operating conditions the oil must be replaced and/or disposed of regularly. Therefore, to assist in the transition of the many renewable marine energy capture systems from concept to useful energy contributor, a low-speed, reliable, gearless generator needs to be available on the market. These generators need to be efficient at low rpm and able to cope with rapidly varying rpm inputs. Today, tidal energy concepts are demonstrated using adapted wind turbine generators, or other types of generators; this decreases efficiency and reliability. Mainstream adoption of marine renewable power has been hampered by the lack of a purpose-designed and directly compatible gearless generator, unlike wind power which has found much greater adoption.
The objective of MAGNETIDE was to develop powder-metallurgically produced soft magnetic materials for use in such generators, and the development and modelling of concept designs for a suitable generator.
A second objective was that the soft magnetic materials being developed within the project would open up opportunities in several industry sectors apart from tidal energy.

Project Results:
MAGNETIDE has developed a method for making commercially viable, soft magnetic materials with magnetic properties that are at least equal to those that are currently available, but which can be cost-effectively manufactured as small, complex three-dimensional shapes using powder/metal injection moulding (PIM/MIM). As the technology matures into the commercialisation phase, the designers of small bespoke generators and motors could have a previously undreamt-of design freedom with respect to the geometry and arrangement of the magnets.

Unfortunately, the manufacturing challenges encountered precluded the manufacture of large magnets, as would be required for tidal generators.

WP1 and WP2 were both completed and reported in RP1.

In WP3, the PM/PIM process window has been defined and product features determined. Component characterisation was carried out to ensure that property requirements have been met. NDT methods were established for detecting heterogeneities and porosity in machined PIM samples using electrical conductivity profile of the PIM samples measured using a four point probe and Eddy Current techniques to detect surface and sub-surface defects.

In WP4, detailed analysis of a low speed permanent magnet (PM) generator was undertaken with two design options. Both 18-20 and 36-40 combinations were considered for the envisaged application. Both design alternatives for the generator were modelled in detail and put forward to the MAGNETIDE consortium for their consideration. Performance comparisons of the generators were carried out and the results of the detailed 2D finite element analyses were reported, along with associated component drawings.

In WP5, two design options for the Mag-Gen low speed permanent magnet (PM) generator were modelled and put forward to the MAGNETIDE consortium. The selected design for the demonstrator generator uses a soft magnetic stator in the centre and a permanent magnet rotor on the outside. Therefore, this WP was focussed on a stator design and not a rotor design, because a different type of generator configuration had been selected. The final selection was made of the specification and manufacturing route for the MAGNETIDE stator for the integrated system prototype generator. A generator using the same design, but commercially available soft magnetic materials (laminated FeSi steel), was built and tested. The manufacturing challenges in making the stator magnets using the MAGNETIDE soft magnetic materials were identified and recommendations made for future work which could improve this aspect.

The intention was for WP6 to undertake the assembly of the second prototype generator using the MAGNETIDE magnetic materials, and for WP7 to benchmark the new generator against the FEA models and against the generator made using commercial magnetic materials. However, the challenges encountered in the manufacture of the MAGNETIDE magnets, as described above, made it impossible to produce magnet segments of sufficient size and integrity to use these in the construction of a full MAGNETIDE prototype, and therefore it has not been possible to fully complete WP6 and WP7 within the timeframe of the project.

Potential Impact:
The MAGNETIDE project planned to develop a methodology for producing high performance soft magnetic alloy components using the metal/powder injection moulding (MIM/PIM) process. PIM processing has the capability of quickly producing low cost, (near) net shape, highly unusual and intricate shape geometry. PIM can produce shapes that would require either a lot of machining or are simply not possible to produce using conventional processing, and would therefore have to be produced in several expensive and time consuming pieces. However, whilst some progress has been achieved with production of materials using this route, a number of processing issues have been identified and further development work is necessary before the MIM process can be utilised as a robust method for producing such components.

The advantages and challenges of the new component geometries that are possible using PIM magnetic materials, and the implications of the associated design freedom to reduce production cost, materials usage and weight has been demonstrated. However, much of this work has been based on theoretical properties achievable by the PIM process; additional validation work will be required when the process is fine-tuned to produce components for different markets.

SME partner ITB has confirmed that this project has generated considerable interest amongst its customers, in production of a soft magnetic grade alloy which has excellent magnetic properties.

Co-ordinating SME partner ATARD, is involved in the development of engineering solutions across a wide variety of industries, and is strongly committed to offering this electromagnetic technology to its customers for applications such as bearings and actuators.

Tidal renewable energy device developer and manufacturer Tidal Sails has been provided with state-of-the-art generator design and analysis, which will contribute to the development of its marine MW-scale generator. Access to a full-size submersible generator, designed to operate efficiently with the output of its renewable energy device, will assist Tidal Sails to progress towards installation of its systems in commercial installations.

List of Websites:
Project website: www.magnetide.eu
Project's co-ordinator: Enis Okan,
Atard
Tel: +90 222 236 85 00
E-Mail: eniso@atard.com.tr