A new low-cost installation scheme of PATs for pico-hydropower to recover energy in residential areas

A limiting factor in the use of hydropower plants in water supply networks consists in the cost of the electromechanical production device and the equipment necessary for the plant regulation. Pumps as Turbines (PATs) are electromechanical devices that have already been used in many mini and micro hydropower plants. Due to their low cost and reliability, PATs are an optimal solution for pico-hydropower plants, whose regulation has been widely analysed in literature, for power installations of only a few kW. A new power plant for small residential areas is presented herein. The new low-cost plant is provided with two PATs, that can work as single, series or parallel (SSP) turbines, and three on/off valves, whose synchronous operations regulate the flows and the head loss. The proposed design method is based on the maximization of the effectiveness of the system. Experimental data on a PAT are used to simulate the plant in several hydraulic conditions, with the application of the turbomachinery affinity law. The simple plant operations and the resulting interactions with the network confirm the viability of the proposed scheme. An economic assessment shows the feasibility of the new plant in different hydraulic situations.