Last few decades the demand for energy is increasing globally and this has led to an increase in CO2 emission. Today, reducing CO2 footprint is an urgent requirement to minimize the global impact of climate change. In an isolated grid system like in Small Island Development States (SIDS), the majority of the electricity is being produced by fossil fuel, therefore these islands are now focusing on Variable Renewable Energy source (VREs). VREs such as wind and solar are unpredictable and could bring instabilities in the electric power system. Energy storage technologies play an important role to cope up with the instability induced by VREs. This thesis focuses on the possibilities of renewable energy storage from the Seawater Pump Storage System (S-PSS) in a Curacao (one of the SIDS nation). This research aims to assess the potential sites for constructing seawater pumped hydro projects. Geographic Information System (GIS) application is used to develop a tool for locating the seawater pumped hydro sites in the given study area. Considering sea as the lower reservoir, two types of upper reservoir sites (dry gully and turkey nest) are assessed in the region of interests. The current and future scenario of electricity consumption and production are analysed to recognise the requirement of energy storage capacity. The concept of using seawater as a source for the pumped hydro project is not in common practice. It is anticipated to have some technical and environmental challenges by S-PSS which are discussed in the thesis. The approach and methodologies developed for this research is applied in Curacao, which has a total coverage area of approximately 444 km2. It is estimated that, in Curacao, to have balanced electric grid system with use of VREs, the requirement of the energy storage capacity for 2035 is 133.88 MWh with a maximum power of 21.10 MW. On the other hand, few feasible S-PSS sites are detected near the cost, which could store the desired energy to have a balanced electricity grid in Curacao. Preliminary ...