The aim of this thesis is to assess the application of underground pumped hydro storage technology to increase the integration of renewable energy production in the Moroccan national grid. This thesis does not look at the specific details necessary for the construction of a UPHS, it only considers the selection of deep underground mines. A future scenario is addressed in this study, the characteristics of the scenario are based on official announcement from the government of Morocco, such as the announcement of a project that aims to increase solar energy production on the chosen site for the case study. First, data collection is carried out for the selection of an area of study in Morocco. The chosen area has three characteristics: Electricity generation through renewable sources, the presence of deep underground areas that can be used for the construction of UPHS, and the presence of transmission lines that allow the transport of energy between the generating unit to the storage unit. The second part of the work focuses on doing calculations to investigate the possibility of implementing a PHS in the selected area. The study shows that the using of pumped hydro storage in out of used mines in Morocco will contribute to increasing the share of the renewable electrical energy production in the national grid as well as shift the peak load and stabilize the grid from the intermittent electrical energy production nature of the renewable resources.