Investigation of the energy component in the management of the water supply system of Athens

Water supply systems contribute 2-3% to the global energy consumption, while 90-95% of this consumption is related to pumping. The water supply system of Athens is particularly complex, is highly energy-consuming due to the usage of the Hylike aqueduct and the boreholes, and may be an identical case for applying measures to improve energy efficiency. The management of the system is carried by EYDAP S.A., which operated under private-economy criteria. From 2000, EYDAP adopted a decision support system to optimize the management of the water supply system. It core is the Hydronomeas software, an advanced model for the simulation and optimization of water resource systems, which also provides options for incorporating economic and energy criteria in water management. Until now the operation cost of the system is evaluated in mean annual energy consumption terms, while the unit cost adapted is the pumping cost, expressed in specific energy units (kWh/m3). In order to identify – in quantitative and qualititative terms – the impacts of specific energy to the activation of pumping stations and boreholes, we formulated three main scenarios of the network operation, thus expressing different conditions of system efficiency. Next, these scenarios have been optimized using Hydronomeas, under two optimization criteria, i.e. the failure probability for the water supply target and the energy consumption. The pumping stations along Viliza-No10, Kremmada-Kleidi and Kiourka-Menidi are the most promising cases for the implementation of energy interventions. Increasing specific energy, the probability of activation is stabilized, after an initial decrease that is due to the increase of energy consumption. Further decrease of this probability is not feasible, since the usage of pumping stations is essential for the fulfillment of drinking water demand. Besides, the activation of boreholes is not sensitive against specific energy, given that their operation directly depends on the actual surface water resources of the system. Finally, the restoration of the bidirectional operation of the Marathon aqueduct will contribute to the reduction of pumping along the Hylike aqueduct, the reduction of leakages and a more reliable operation of the system.