**Energy Saving in a Water Supply Network by Coupling a Pump and a Pump As Turbine (PAT) in a Turbopump**

#### **Armando Carravetta 1, Lauro Antipodi 2, Umberto Golia 3 and Oreste Fecarotta 1,\***


Academic Editor: Helena Ramos and Arjen Y. Hoekstra Received: 28 October 2016; Accepted: 9 January 2017; Published: 20 January 2017

**Abstract:** The managemen<sup>t</sup> of a water distribution network (WDN) is performed by valve and pump control, to regulate both the pressure and the discharge between certain limits. The energy that is usually merely dissipated by valves can instead be converted and used to partially supply the pumping stations. Pumps used as turbines (PAT) can be used in order to both reduce pressure and recover energy, with proven economic benefits. The direct coupling of the PAT shaft with the pump shaft in a PAT-pump turbocharger (P&P plant) allows us to transfer energy from the pressure control system to the pumping system without any electrical device. Based on experimental PAT and pump performance curves, P&P equations are given and P&P working conditions are simulated with reference to the operating conditions of a real water supply network. The annual energy saving demonstrates the economic relevance of the P&P plant.

**Keywords:** energy saving; Pump As Turbine (PAT); PAT and pump system (P&P); energy recovery; pumping
