Energy Saving in Water Distribution Network through Pump as Turbine Generators: Economic and Environmental Analysis

Abstract

Abstract:Complex systems of water distribution networks (WDS) are used to supply water to users. WDSs are systems where a lot of distributed energy is available. Historically, this energy is artificially dissipated by pressure reduction valves (PRVs), thanks to which water utilities manage the pressure level in selected nodes of the network. The present study explores the use of economic hydraulic machines, pumps as turbines (PATs) to produce energy in a small network located in a town close to Palermo (Italy). The main idea is to avoid dissipation in favor of renewable energy production. The proposed study is applied to a WDN typical of the Mediterranean countries, where the users, to collect water during the period of water scarcity conditions, install private tanks. The presence of private tanks deeply modifies the network from its designed condition. In the proposed analysis, the economic benefit of PATs application in water distribution networks has been investigated, accounting for the presence of users' private tanks. The analysis, carried out by mean of a mathematical model able to dynamically simulate the water distribution network with PATs, shows the advantage of their installation in terms of renewable energy recovery, even though the energy production of PATs is strictly conditioned by their installation position.

A New Device for Pressure Control and Energy Recovery in Water Distribution Networks

“…More complex turbine types, like Francis [14], are usually too expensive for the produced power, also because high values of the efficiency curve are restricted to a small interval around the design discharge against a strong hourly variability of the actual discharge. The only device largely used inside pipes, far from open water tanks and for relatively small discharge values, is the PAT, because traditional Cross-flow turbines have atmospheric pressure outflow [15][16][17][18]. New micro turbines, like tubular propellers [19,20], have not yet attained a satisfactory efficiency during variable flow conditions.…”

Optimization of Guide Vane Closing Schemes of Pumped Storage Hydro Unit Using an Enhanced Multi-Objective Gravitational Search Algorithm

“…As a special energy storage power supply, wind power-pumped storage plant (PSP) and solar power-PSP are used as the most common centralized and large-scale renewable energy complementary operation means [3][4][5][6][7]. The flexibility of PSP makes up for the randomness and heterogeneity of wind power and solar power generation, which is helpful to improve the reliability of the power grid and promote the integration of renewable energy variables.…”

Speed and Pressure Controls of Pumps-as-Turbines Installed in Branch of Water-Distribution Network Subjected to Highly Variable Flow Rates

“…WDNs constitute typical case studies where the control of pressure inside network branches through PRVs is crucial, as previously reported [26][27][28][29][30]. De Marchis et al [31] developed a dynamic mathematical model for intermittent WDNs in the city of Palermo located in Sicily (Italy): they integrated PaTs in the model and demonstrated their effectiveness to recover energy that would otherwise be wasted. Carravetta et al [32] studied possible different hydraulic conditions that can occur in WDNs and they examined five different regulation systems in order to overcome them.…”