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This paper presents the design and analysis of an electromechanical flywheel energy storage system to enhance rural electrification in sub-Saharan Africa. The system consists of a flywheel rotor, an electrical machine, control system, bearings, and a containment structure. With the exception of the power electronics and magnets, local materials were used for the manufacture of the flywheel system. The flywheel rotor is made from glass fiber-epoxy composite, designed using novel shape profiles and utilizes a stress based solution by introducing a central hole for shaft inclusion. The system was accelerated to 6000 r/min storing up to 227 kJ. Numerical stress analyses were performed during the design stage to ensure that the maximum tensile strength is not exceeded. A lumped parameter thermal model is used to estimate the temperature distribution to ensure safe operating conditions of the flywheel system and environment. A life cycle cost analysis performed found that by integrating a flywheel system into a Solar Home System implies a cost savings of 35% per kilowatthour when compared with lead-acid batteries.
Date of Publication: Dec. 2011