The DEMIKS project was carried out to create, construct and initially test a real‑world demonstrator for rotational kinetic energy storage (RKS) systems. The target specifications were a storage capacity of up to 500 kWh and a charge‑discharge power of 500 kW. The demonstrator was to be mounted on a wind turbine platform, thereby providing a test bed for improving the flexibility of renewable‑energy generators. The technical concept centred on a modular hardware structure comprising a rotor unit that functions as a flywheel, a bearing system, a stator unit, a braking device, a vacuum chamber and an electric machine that serves as both motor and generator. The rotor is positioned vertically and supported by two hydrodynamic radial bearings and a hydrostatic axial bearing. The vacuum chamber surrounding the rotor reduces losses caused by speed‑dependent fluid drag. The electric machine couples the mechanical energy of the rotor to the electrical grid, allowing efficient energy transfer during charging and discharging. In addition to these core components, the design incorporates essential subsystems such as a frequency converter, a transformer for grid‑compatible power control, hydraulic, electrical, pneumatic and sensor networks, and the necessary control technology. The overall architecture was laid out in a preliminary design that guided the detailed engineering and construction phases.
The project was organised into eleven main work packages, each subdivided into further tasks, and spanned 36 months from 1 December 2016 to 31 August 2021. The work packages covered requirements analysis, hardware concept development, software concept development, test environment design, hardware construction, and experimental verification of the demonstrator solution. The experimental phase involved the first operation of the RKS demonstrator, validating the integration of the mechanical, electrical and control subsystems and demonstrating the feasibility of the 500 kWh/500 kW target. While the report does not provide detailed efficiency figures, the design emphasises loss minimisation through vacuum operation and advanced bearing technology, and the demonstrator’s performance is expected to confirm the viability of large‑scale RKS for grid support.
Collaboration was carried out by a consortium of seven partners. The Technical University of Dresden (TUD) acted as the project coordinator and lead partner, with Prof. Dr.-Ing. Frank Will as project manager. IBAF Engineering GmbH, represented by Sebastian Mieth, contributed expertise in mechanical design and manufacturing. SKM GmbH, led by Steffen Söll, supplied knowledge in power electronics and control systems. Adenso GmbH, headed by Uwe Beier, provided components for the vacuum and bearing systems. BITZs electronics GmbH, represented by Dr.-Ing. Sven Schmidt, supplied sensor and instrumentation solutions. VSB Service Deutschland GmbH, led by Andreas Kiss, offered services in system integration and testing. The consortium was funded by the German Federal Ministry of Economics and Energy (BMWi) under the 6th Energy Research Programme “application‑oriented non‑nuclear research and development – Energy storage” (grant number 03ET6102 A‑F) and was administered by the project host Jülich. This partnership combined academic research, industrial manufacturing, and system integration expertise to deliver a demonstrator that bridges the gap between laboratory concepts and real‑world deployment of rotational kinetic energy storage.