Potential of energy recovery and water saving using micro-hydropower in rural water distribution networks

Abstract

Water distribution networks have a significant water and energy demand and, therefore, must face the challenge of adopting measures that improve how these resources are used. Previous investigations have demonstrated the potential of micro-hydropower energy recovery in reducing both energy consumption and water leakage in urban water supply networks. In this work, the potential of hydropower energy recovery combined with leakage reduction has been evaluated in eight rural water distribution networks in Ireland. Two scenarios were evaluated. Scenario 1 consisted of replacing the devices currently being used to reduce pressure with a pump as turbine (PAT). In Scenario 2, potential new locations were proposed for existing sites with excess pressure, according to the flow and elevation of the network. The hydropower generated and leakage reduction due to lower pressure at the nodes were both estimated. The results showed that the estimated hydropower could reduce the net energy demand by 21% in Scenario 1 and by up to 23% in Scenario 2 in some of the networks. However, in many of the networks the amount of energy recoverable was low due to the relatively low water demand in these rural settings. In Scenario 1 three out of the eight rural water networks were found to have economically viable micro-hydropower sites. However, in Scenario 2 the significant water savings achieved as a consequence of leakage reduction made the installation of PATs feasible in all the networks evaluated. The results of this investigation highlight that while energy recovery using micro-hydropower in rural water supply networks produces only modest amounts of power in comparison with urban settings, this power can contribute significantly as a proportion of local energy demand. In addition, combining water savings with energy production greatly improves the economic viability of these micro-hydropower installations.