The pumped hydro energy storage (PHES) is a well-established and commercially-acceptable technology for utility-scale electricity storage and has been used since as early as the 1890s. Hydro power is not only a renewable and sustainable energy source, but its flexibility and storage capacity also make it possible to improve grid stability and to support the deployment of other intermittent renewable energy sources such as wind and solar. As a r. The pumped hydro energy storage (PHES) is a well-established and commercially-acceptable technology for utility-scale electricity storage and has been used since as early as the 1890s. Hydro power is not only a renewable and sustainable energy source, but its flexibility and storage capacity also make it possible to improve grid stability and to support the deployment of other intermittent renewable energy sources such as wind and solar. As a result, a renewed interest in PHES and a demand for the rehabilitation of old small hydro power plants are emerging globally. With regard to PHES, advances in turbine design are required to enhance plant performance and flexibility and new strategies for optimizing storage capacity and for maximizing plant profitability in the deregulated energy market. In the early 2000s, this technology has again emerged as an economically and technologically acceptable option for peak load shaving and wind and solar energy storage for power quality assurance. Furthermore, renewable energy sources due to their fluctuating nature cannot maintain or regulate continuous supply of power and hence require bulk electricity storage. The present study aims at reviewing the existing global PHES capacities, technological development, and hybrid systems (wind-hydro, solar pv-hydro, and wind-pv-hydro) and recommending the best possible options. The review explores that PHES is the most suitable technology for small autonomous island grids and massive energy storage, where the energ. Pumped hydroelectric systemsWind-hydro energy storagePhotovoltaic-hydro energy storageSeawater pumped storageEconomicsRenewable energyCSP concentrated solar thermal powerESS energy storage systemGW gigawattMPT micro-pump turbineMW megawattPHES The adverse effects of globally changing climatic conditions due to human interference in the natural eco-system of the life cycle have led people to minimize such activities which are leading the planet towards destruction. People from different walks of life have realized the consequences of using fossil fuels and are developing and utilizing clean and renewable sources of energy. These sources of energy include wind, solar photovoltaic, solar thermal, geothermal, hydroelectric, biofuels, biomass, wave, tidal, etc. Of these, wind and solar sources have taken the lead due to their technological maturity and commercial acceptance. The global deployment and investment of these sources are increasing year to year as can be seen from the literature. Furthermore the high cost of generation, dependence on fossil fuels and environmental considerations have been a powerful driver for increasing the exploitation of the renewable energy potential during the last decades,.The present review aims at understanding the existing technologies, practices, operation and maintenance, pros and cons, environmental aspects, and economics of using pumped hydroelectric energy storage (PHES) systems to store energy produced by wind and solar photovoltaic power plants.According to the latest update, global investment in the development and utiliz. Pumped hydroelectric energy storage stores energy in the form of potential energy of water that is pumped from a lower reservoir to a higher level reservoir. In this type of system, low cost electric power (electricity in off-peak time) is used to run the pumps to raise the water from the lower reservoir to the upper one. During the periods of high power demand, the stored water is released through hydro turbines to produce electric power. Reversible turbine/generator assemblies act as pump or turbine, as necessary. Typical conceptual pumped-hydroelectric-storage (PHES) systems with wind and solar photovoltaic power options for transferring water from lower to upper reservoir are shown in Fig. 4, Fig. 5, respectively. The technique is currently the most cost-effective means of storing large amounts of electrical energy, but capital costs and the presence of appropriate geography are critical decisive factors. The design of almost every PHES power plant is highly dependent on the site characteristics. A site having sufficient water available is said to be good for the development of PHES plant, if the topography and geology of the area are favorable.Pumped storage is generally viewed as the most promising technology to increase renewable energy penetration levels in power systems and particularly in small autonomous island grids. The wind and pumped-storage systems, call.
