Pumped-Storage Solution towards Energy Efficiency and Sustainability: Portugal Contribution and Real Case Studies

This paper aims at presenting different pumped-storage solutions for improving the energy effi-ciency and economic sustainability of water systems. The assessment of pumped-storage solutions, either using fresh water or sea-water, is seen as a viable option to solve problems of energy pro-duction, as well as in the integration of intermittent renewable energies, providing system flex-ibility due to energy loads ’ fluctuation, as long as the storage of energy from intermittent sources. Pumped-storage is one of the best and most efficient options in terms of renewable resources as an integrated solution allowing the improvement of the energy system elasticity and the global system efficiency. Two real case studies are presented: a fresh water system installed in a river dams—the Alqueva system, in Portugal—and a sea-water system in an arid region of the Cape Verde Islands in Africa. These cases demonstrate the benefits associated to pumped-storage solu-tions, depending on the storage volume capacity, operational rules and energy tariffs