Motor generators offer acceleration and economy

Magnetic loaded composite rotor magnets are key to high-speed flywheel motor generators developed for F1 racing, but have a range of potential applications in heavy goods vehicles, for smoothing energy delivery from renewable sources and to metro rail systems. The motor technology was originally developed by Urenco for uranium enrichment centrifuges running at 40,000 to 65,000 rpm or even faster. Magnetic loaded composite (MLC) consists of iron or oxide metallic particles in a polymer matrix and has the advantages that, because the particles are separated, there is no little or no possibility of eddy currents and, should the rotor come apart, there are no flying lumps of magnet. Although the exact material that constitutes the MLC used by Urenco and Williams is unknown, there have been a family of such materials commercially available for some years from the Swedish company Höganäs, which are sold under the 'Somaloy' brand name. These consist of iron and iron oxide based powders in a matrix of fatty acid amides and/or PPS – polyphenylene sulphide. After trying to market the spinoff high energy flywheel technology themselves, it was subsequently acquired by Automotive Hybrid Power, based in Norfolk. In April 2008, Williams Grand Prix Engineering took a minority shareholding in AHP, and the business transferred to the Williams F1 site in Oxfordshire and was renamed Williams Hybrid Power. Williams developed and tested it as a KERS (Kinetic Energy Recovery and Storage) system for its F1 cars and is now continuing to develop it for road cars and other applications, including the Porsche 911 GT3 R Hybrid car showcased at this year's Geneva Motor Show Apart from F1 and Porsche, Damien Scott, the general manager for Williams Technology in Doha, Qatar, told us that discussions are ongoing with a number of major manufacturers, and WHP is one of the main participants in the Technology Strategy Board backed 'KinerStor' project which aims to develop flywheel energy storage systems for a cost of less than £1,000 per vehicle for mass produced road vehicles. A major advantage that a motor-driven flywheel has over the competitive Torotrak gearbox approach is that there is no need for a vacuum shaft seal. The flywheel has to be maintained in a vacuum chamber in order to eliminate not only air drag but possible supersonic shockwaves. Furthermore, in a vehicle that is already an electric hybrid, Scott says: "It is much easier to integrate it into the vehicle system and use of an electrically connected flywheel gives flexibility as to its location", because it does not have to be placed next to or integrated into the gearbox", if there is one. In the case of a fuel cell or battery powered vehicle, there would, of course, not be a mechanical gearbox. There have also been a number of reports and studies of using high-speed, electrically-driven flywheels to provide smoothing of both energy supply and delivery. There have been trials on the London Underground, which are said to have been successful, and there are some light rail installations in Germany. A larger scale application that has been studied in innumerable reports is the storage of energy from intermittent renewable energy sources such as wind and wave power so as to provide a smoother output. In the USA, the Massachusetts company Beacon Power announced on March 18th 2010 that it had shipped, installed and successfully connected a 'Smart Energy' 25 'Gen4' flywheel energy storage system at a wind farm in Tehachapi, California. The system is part of a wind power/flywheel demonstration project being undertaken for the California Energy Commission.