Das Projekt "Entwicklung eines Schwungradspeichers zur Energieeinsparung in Krangetrieben" wird vom Umweltbundesamt gefördert und von Krupp Forschungsinstitut durchgeführt. General Information: Friedrich Krupp GmbH has investigated for cranes the possibility of saving energy, by recovering mechanical energy from the heavy hook, when it is lowered, and storing it in flywheel energy storage systems. Krupp examined several crane types for the best flywheel application. They took into consideration different criteria and classified the different cranes in order of priority. Finally, they selected one type with a power of 150 kw. Calculated results indicate that while the payback period for retrofitting a crane of this type is too long (average 21 years), the payback period for a new crane is at an acceptable limit (average 7.8 years). The above results were obtained for a crane mechanically coupled to a flywheel by using gears. The coupling can also be brought about electrically. The last solution is somewhat more expensive but has a higher reliability. A scaled down electrically coupled flywheel of 10 kw was experimentally tested. Apart from the energy saving the electrical version had the advantage of a smoother up take of electricity which reduces the power requirements from the grid.