Deep-sea Pumped Hydro Storage

Deep-sea pumped hydro storage is a novel approach towards the realization of an offshore pumped hydro concept, which uses the pressure in deep water to store energy in hollow concrete spheres—also known as the StEnSea (Stored Energy in the Sea) technology. This chapter presents the fundamental working principles and the results from the corresponding StEnSea research project. It covers strengths and opportunities as well as challenges for the further development of the technology.