Optimal Selection and Operation of Pumps as Turbines for Maximizing Energy Recovery

Abstract

A pump as turbine (PAT) can be a cost-effective and versatile solution to recover energy in several fields of application. However, its optimal exploitation requires a reliable and general methodology for selecting the optimal turbomachine. To this purpose, this paper presents and validates a comprehensive methodology that identifies the best turbomachine (i.e., the one that maximizes the recovered energy) by considering two hydraulic sites and forty-five PATs. In both sites, the methodology correctly identifies the best PAT, which allows for the recovery of up to 45% of the available hydraulic energy. To further investigate PAT potential, an additional layout of installation, which comprises two PATs installed in parallel, is also considered. The operation of both PATs is optimally scheduled to maximize energy recovery. As a result, the energy recovered by the best pair of PATs is almost 50% of the available hydraulic energy. An in-depth analysis about PAT operation (i.e., operating range, causes of wasted energy, timeframe of operation and PAT efficiency) reveals that the installation of two PATs is actually recommended in just one of the two considered sites.