Book excerpt: The available literature on energy storage technologies in general, and mechanical energy storage in particular, is lacking in terms of both quantity and quality. This edited volume focuses on novel (yet uncomplicated) ideas that are currently part of the Energy Storage curriculum at the University of Sharjah, UAE. These techniques have been extensively researched and their prototypes are central to the undergraduate Energy Storage Lab that is associated with the course. Although ideally suited for wind energy storage, the techniques described are also suitable for renewable energy storage in general, and offer high two-way efficiency ratings.