Author(s): A. Morabito; J. Steimes; P. Hendrick
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Abstract: The technical and economic feasibility of Pumped Hydroelectric Energy Storage (PHES) is increasingly under discussion. Its important capital cost may be mitigated by its relevance in balancing the electrical grid. Indeed renewable energy intermittency forces electric power industry to find new solutions for the regulation of the electric grid. PHES systems are built around hydraulic and electrical machines. The site head and the flow rate primarily define the type of hydraulic machine used. In this paper three configurations are discussed: traditional applications that include separate hydraulic machines (turbines and pumps), Reversible Pump Turbines (RPTs) and Pumps as Turbines (PATs) that can operate in both modes of operation. A detailed estimation of the PATs performance is computed to predict and interpret their behaviour during reversed operation: therefore different prediction models are listed and analyzed. A case study compares different system efficiencies and capacity for different configurations. This PHES consist in a unused mine with a depth of 350 meters and it is equipped with one or more Francis turbine or with PAT unit. The available head heavily varies with interittency due to the peculiar mine configuration. Consequently the hydraulic machines adopted could often work in offdesign conditions. Results show that regarding micro and small power plants the solution using PATs is an available and suitable option.
Year: 2016