Comparison of PAT Installation Layouts for Energy Recovery from Water Distribution Networks

This paper analyses and compares different layouts for the installation of pumps used as turbines (PATs) to advantageously couple pressure regulation with hydropower generation in water distribution networks (WDNs). The layouts differ in terms of the type of regulation adopted for adjusting PAT operation to time-varying conditions of available flow and head during the day. In fact, while offering a number of feasible layouts for PAT installation (hydraulic regulation, electric regulation, coupled hydraulic and electric regulation), the literature provides no clear indication as to the layout deemed most suitable. The paper contributes to resolving the open question of determining the most effective and appropriate installation layout for different flow and head patterns by means of a comparative cost-benefit analysis - specifically, technical, and economic analysis - of the layouts considered. Overall, the results from four case studies that vary in terms of available flow and head show that the hydraulic regulation-based installation layout represents the best trade-off between energy produced and installation costs. The solely electrical regulation option exhibits poor flexibility for accommodating yearly demand variations.