Energy saving with variable speed pumps in on-demand irrigation systems

The present work analyzes energy saving in on-demand irrigation systems served by an upstream pumping station. The objective of this work is to identify the best pumping station operating mode to optimize energy consumption. This objective can be achieved by matching the discharge and the pressure head required by the network (characteristic curve of the network) during the whole irrigation season with the pumping station characteristic curves. The characteristic curve of the network can be obtained using an appropriate stochastic generation modeling, and COPAM software was used in the present work. The characteristic curves of the pumps can be adapted to the network characteristic curve by equipping the pumping station with variable speed devices. Several types of regulation based on variable speed techniques were identified and analyzed. The differences in energy consumption for each technique were quantified for two on-demand irrigation districts in Southern Italy and managed by the Water Users Organization “Consortium of Capitanata” . It was demonstrated that in comparison with the current pumping station regulation, energy savings of about 27 and 35% may be achieved for the two districts.