Wind powered pumped-hydro storage systems for remote islands: A complete sensitivity analysis based on economic perspectives

The electrification of the non-interconnected Greek islands is mainly based on Autonomous Power Stations (APSs) that are characterized by considerably high electricity production cost, whilst, in several cases, problems related with power shortage are encountered. At the same time, the contribution of wind energy is significantly restricted due to electrical grid limitations imposed to “secure” the stability of the local network and thus resulting in significant rejected wind energy amounts. On the basis of sensitivity analysis, the present study evaluates the techno-economic viability of a system that incorporates the simultaneous operation of existing and new wind farms (WFs) with pumped storage and hydro turbines, which are able to provide the electrical grid of a remote island with guaranteed energy amounts during the peak load demand hours on a daily basis. The performance of the system is simulated during a selected time period for various system configurations and an attempt is made to localize the optimum solution by calculating various financial indices. Emphasis is given on the conduction of an extensive sensitivity analysis considering three main variables (i.e. produced energy selling price, the percentage of state subsidization and the price of the wind energy surplus bought from the already existing WFs) taking also into account several constraints of the national legislation. Based on the most economically viable (payback period quite less than 10 years) configuration derived (24 MW WFs, 15 MW water pumping system, 13.5 MW hydro turbines), the contribution of renewable energy increases by almost 15% (in absolute terms) compared to current conditions, reaching about 25% of the island’s energy consumption pattern. The proposed analysis may be equally well applied to every remote island possessing remarkable wind potential and appropriate topography.