Wind powered pumped hydro storage systems, a means of increasing the penetration of renewable energy in the Canary Islands

A significant number of islands have found themselves obliged to place restrictions on the penetration of renewable sourced energy in their conventional electrical grid systems. In general, this has been due to certain energy related characteristics often connected to their very nature as islands. These limitations attempt to prevent the appearance of problems that might affect the stability and safety of the electrical system. The restrictions imposed on the direct penetration of wind sourced energy in the conventional grids of the Canary Islands are an obstacle to meeting the renewable energy objectives set out by the European Union. As a partial solution to the problem, this paper proposes the installation on Gran Canaria island (Canarian Archipelago) of an appropriately administered wind powered pumped hydro storage system. The results obtained from the application of an optimum-sized economic model of such a system indicates that penetration of renewable sourced energy can be increased by 1.93% (52.55 GW h/year) at a competitive cost for the unit energy supplied. These results are obtained on the hypothesis that two of the largest existing reservoirs on the island (with a difference in height between the two of 281 m and a capacity of some 5,000,000 m3 used in each) are employed as storage deposits. Investment, operating and maintenance costs are taken into account, as well as those costs involving health and environmental damage associated with energy production and use (externalities). The system would consist of: a wind farm with a rated output of 20.40 MW; a modular pumping station with a rated output of 17.80 MW, operated so that the variation in the energy demand for pumping is in sympathy with the wind generation; and a hydraulic plant with a rated output of 60.00 MW. The proposed system would have no negative effect on either the reliability of the electrical system or consumer satisfaction. Furthermore, it would mean a fossil fuel saving of 13,655 metric tonnes/year and a reduction in CO2 emissions into the atmosphere of 43,064 metric tonnes/year. For regions that have topographically suitable sites and which suffer energy problems similar to those of the Canary Islands it is thus suggested that an analysis be made of the technical and economic feasibility of the installation of power systems such as that proposed in this paper. Within the general guiding framework of a policy promoting clean and renewable energy, these systems represent an enormous and as yet barely explored potential.