Kinetic energy storage and fast-rotating machines

© TU Graz/IME
For more than 5 years, the Institute of Machine Elements and Development Methodology has been working on Flywheel Energy Storage Systems (FESS). It is a system for storing energy - similar to batteries and rechargeable batteries. The difference is that the energy is stored in the form of kinetic energy of a spinning rotor. As a rule, the rotor is accelerated by an electric motor (energy storage is charged) or delayed (energy is removed from the storage). The energy content of the rotor increases with the square of the speed, which is why as the optimization progresses, the systems become increasingly compact and fast-rotating. The following figure shows the schematic structure of different FESS concepts:
Gegenüberstellung unterschiedlicher FESS-Konzepte
© TU Graz/IME

Over the past 5 years of research, a number of publications on FESS have been published. Furthermore, two working prototypes of kinetic energy storage devices for mobile applications have been developed, built and commissioned in cooperation with industrial partners:

CMO – Clean motion offensive

TSA – High Fly

FESS are not only suitable for mobile applications. The basic conditions regarding weight, self-discharge, energy content and energy density are fundamentally different from those of mobile applications. The realization of a stationary energy buffer for solar power in single-family homes is currently being dealt with as part of a research project. Self-discharge to preserve the energy overnight is of fundamental importance. Technically this is shown by the self-discharge testbed

Another research focus is the storage of fast-rotating systems, which has emerged as a critical component. Ongoing research deals with different aspects of rolling bearing systems. This includes, among others:

  • Bearing life increase by passive and active methods

  • Loss moment minimization to reduce self-discharge

  • Quantification of the thermal conductivity of rolling bearings

  • Optimization of the lubrication situation

Antriebsstrank eines PKW mit Flywheel
© TU Graz/IME

Institute of Machine Components and Methods of Development

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8010 Graz

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