Multi-criteria decision analysis for optimal placement of pumped hydro-energy storages: the case of existing hydropower reservoirs of Ethiopia

Abstract Understanding the optimal placement of pumped storage power plants is an important aspect of the provision of reservoirs for peak load power generation. This study presents a MCDA GIS-based optimal placement of pumped hydro-energy storage potentials and the appropriate siting of PHES for existing hydropower reservoirs in Ethiopia. This method involves the use of an integrated approach of decision factors that govern the selection of PHES sites, including head, slope (degree), head to length ratio, topographic wetness index (TWI), lineaments, distance from grid, roads and rivers to define the criteria and constraints that are considered for the optimal placement of pumped hydropower energy storage. The results of this pairwise comparison matrix depicts that head, head to distance ratio, TWI, and slope are the most significant factors in determining whether an area is suitable to PHES, with weights of 29.8%, 17.9%, 15.9%, 11.7%, 6.9%, 5.8%, 5.6% and 6.3%, respectively. The PHES promising potential sites were identified to be suitable for optimal placement of PHES in Ethiopia around existing hydropower reservoirs, the most suitable areas are found in the northern part of the country and include GERD, Gibe I & III, Koka, Finchea, GD III, Melkawakena and Tekeze reservoirs. This study supports the Ethiopian renewable energy policy which proposes to effectively utilizing the advantages of PHES to maximize the energy utilization of the country and PHES plants will creating a balance between the supply and demand of energy during peak load hours. Moreover, this study will serve as a good reference for making well-informed decisions to address energy insecurity in Ethiopia. This research will help policymakers make wise decisions and researchers will proceed with further studies to determine the integration of hydropower reservoirs and other renewable energy sources for sustainable water resource management.