Integration of electricity cost saving interventions on a water distribution utility

The efficient usage of electricity in the South African water industry has not been a priority due to the relatively low cost of electricity in the past. The situation has changed over the past years as a result of the rapid increase in electricity costs. South African water distribution utilities (WDUs) have installed capacities up to 450 MW. Not all WDUs operate efficiently. Therefore an intervention is needed to move towards efficient use of electricity in the South African water industry. Large combined installed capacity of the pumps and the large storage capacity make WDUs good candidates for load shifting projects. Due to the scale of the WDU and the complexity, the electricity cost saving approach needs to be integrated. Such an integrated approach could not be found in literature. An investigation methodology, as well as an integration strategy for the implementation of an electricity cost saving intervention is developed. The proposed integrated strategy is simulated and an optimised approach is developed. The proposed approach is implemented on a large water distribution utility in South Africa. The project realised an average electricity peak load shift of 15.4 MW. It is concluded that load shifting is possible on individual pumping stations in the water distribution utility subsystems.