Djordje Mitrovic
Water distribution networks (WDNs) are one of the most essential infrastructure for normal functioning of the modern society. Supplying water from the sources to our taps is very energy intensive process. Leakages present in the networks further decrease the efficiency of the water supply. Leakages in WDNs do not represent only the water losses but also significant energy losses embedded in treatment and distribution (pumping) of the lost water. For perspective, on the level of EU the values of water losses span from single digit values in Germany, Denmark and Netherlands up to around 45% in Ireland, with an average of 23% (EurEau, 2017). One strategy that has been extensively used by water practitioners to control and thus reduce leakage is division of the networks in smaller sectors, so called district metered areas (DMAs) (Vicente et al., 2016). DMAs are the sectors of WDNs with defined boundaries where the flow that comes in and leaves is constantly metered for leakage monitoring. If there is excess pressure at the entrances of these sectors that is not necessary for normal operation of downstream consumers the practitioners also install pressure reduction valves (PRVs) to further reduce leakages rate as it is well known that it is a function of the pressure (van Zyl, 2014).
However, the excess pressure (i.e., excess energy) that is dissipated at the PRVs is irreversibly lost. Here in Dwr Uisce project our team investigates the potential of improving the energy efficiency of the WDNs by coupling the classical pressure management with hydropower generation. In other words, we investigate the potential of replacing (or coupling) the PRVs with hydropower turbines which would use the existing excess pressure for generation of clean renewable electricity. In terms of hydropower turbines, pumps as turbines (PATs) found to be the most suitable for this application primarily because of their significantly lower cost in comparison to the traditional turbines, which is the result of their mass production (García et al., 2019). The focus of the smart network control work package is to define algorithms for the optimal selection and control of these devices in WDNs. In addition, we investigate strategies to find the optimal number and locations within the networks for installation of these devices to maximize the energy recovery but also minimize the installation costs.
An example of PAT application in a pilot site at SMPGA's drinking water facility in St Pair sur Mer in Normandy (REDAWN Project).https://www.redawn.eu/case-study/drinking-water-networks-france
Reducing the energy consumption for water supply through the implementation of hydropower energy recovery can be one of the solutions for mitigating the impacts of the current energy crisis.
References
EurEau, 2017. Europe’s water in figures.
García, I.F., Novara, D., Mc Nabola, A., 2019. A Model for Selecting the Most Cost-Effective Pressure Control Device for More Sustainable Water Supply Networks. Water 11, 1297. https://doi.org/10.3390/w11061297
van Zyl, J.E., 2014. Theoretical Modeling of Pressure and Leakage in Water Distribution Systems. Procedia Eng. 89, 273–277. https://doi.org/10.1016/j.proeng.2014.11.187
Vicente, D.J., Garrote, L., Sánchez, R., Santillán, D., 2016. Pressure Management in Water Distribution Systems: Current Status, Proposals, and Future Trends. J. Water Resour. Plan. Manag. 142, 04015061. https://doi.org/10.1061/(ASCE)WR.1943-5452.0000589