Energy storage in composite flywheel rotors

[摘要] ENGLISH ABSTRACT: As the push continues for increased use of renewables on the electricity grid, theproblem of energy storage is becoming more urgent than ever. Flywheels withwound, composite rotors represent an efficient and environmentally friendly optionfor energy storage. They have already been applied successfully for voltage controlon electrical rail networks and for bridging power in backup UPS systems, but latelythey have also proven useful for grid-scale frequency regulation.For flywheels to be deployed on a wider scale, the high cost associated with thetechnology will have to be addressed. An important driver of cost is the density atwhich energy can be stored. Currently, flywheel designs do not consistently achievehigh energy density, and this study investigates the reasons for this.A critical analysis is made of the design methodologies that have been proposed inthe available literature, and some improvements are suggested. Most notably it isshown that significant improvements in energy density may be possible if the designoptimization problem is formulated carefully.In addition, the problem of material selection is discussed, because material propertieshave a significant influence on energy density. Some guidance is given forflywheel designers on how to choose an optimal set of materials without invokingundue computational effort. It is hoped that these suggestions may be carriedforward as a topic of further research.

[发布机构] Stellenbosch University