Hydropower Potential in Water Distribution Networks: Pressure Control by PATs

Abstract

Pressure control is one of the main techniques to control leakages in Water Distribution Networks (WDNs) and to prevent pipe damage, improving the delivery standards of a water supply systems. Pressure reducing stations (PRSs) equipped by either pressure reducing valves or motor driven regulating valves are commonly used to dissipate excess hydraulic head in WDNs. An integrated new technical solution with economic and system flexibility benefits is presented which replaces PRSs with pumps used as turbines (PATs). Optimal PAT performance is obtained by a Variable Operating Strategy (VOS), recently developed for the design of small hydropower plants on the basis of valve time operation, and net return determined by both energy production and savings through minimizing leakage. The literature values of both leakages costs and energy tariffs are used to develop a buisness plan model and evaluate the economic benefit of small hydropower plants equipped with PATs. The study shows that the hydropower installation produces interesting economic benefits, even in presence of small available power, that could encourage the leakage reduction even if water savings are not economically relevant, with consequent environmental benefits.

Simulated Annealing in Optimization of Energy Production in a Water Supply Network

“…In WSNs, particularly in cities with considerable geodesic differences, areas exist where the pressure is greater than necessary. In certain cases, energy dissipation is imperative to minimize leakage (Carravetta et al 2012;Carravetta et al 2013;Xu et al 2014;Fecarotta et al 2015). This dissipation is usually ensured by pressure reduction valves.…”

Optimization of Osmotic Desalination Plants for Water Supply Networks

“…The calculated costs for case study CS1, pump and store, and HPP with constant electricity price (the reference case) are given in Table 1. Based on a recent analysis of energy tariff for many countries (Fecarotta et al 2014) an average energetic cost of 0.08 $/kWh has been fixed both for energy selling or purchasing. The RO cost is approximately 85 % of the total, and that the reservoir cost is as large as 10 % of the total.…”

“…Hydro Power Plants (HPP) represents a good alternative to PRV, reducing pressure and enhancing the energy efficiency of the water systems (Punys et al 2011;McNabola et al 2011;Gaius-obaseki 2010;Ramos et al 2010;Carravetta et al 2012). A new strategy is now available (Fecarotta et al 2014;Carravetta et al 2014aCarravetta et al , 2014bFecarotta et al 2016) for the design HPP using pump as turbines (PAT), in the presence of variable operating conditions, i.e. daily variations of user demand, flow rate and available head.…”

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

“…Ramos et al [34] showed that the cost of a PAT is much smaller if compared with the cost of a classic turbine, with unit costs ranging between 200 e /kW and 400 e /kW, where the turbine cost ranges between 300 e /kW and 800 e /kW. Carravetta et al [35] showed that the payback period of a PAT energy recovery system could be really short, ranging between 6 months and 3 years, while Fecarotta et al [36] showed that the coupling of the pressure control strategy with an energy recovery strategy within a water network could be convenient if the valves are replaced by PATs, with high 10 year net present values. Other studies propose different solutions for the regulation of the PAT plant to address the large variability of hydraulic characteristics and to match the turbine head and discharge with the needs of the network.…”

“…In 2014 , Carravetta et al [38] compared the effectiveness of the different installation schemes of a PAT plant. Other preliminary studies have included an analysis of the optimal location of a PAT within a WDN [36,39,40] to maximize the power production.…”