Examining the Relationship between Pumping Energy and Geographically-Targeted Water Conservation Measures in Municipal Water Distribution Networks
water distribution network energy requirements , water conservation planning
Municipal water distribution systems are operated and maintained by utilities whose first priority is the safe and reliable provision of drinking water to consumers. The cost to move and treat water through distribution networks is significant and can account for up to 80% of a utility’s energy costs. As these networks age, operating and maintenance costs continue to increase due to higher incidences of leaks and breaks and increased pipe friction leading to higher energy use. Many utilities are considering water conservation as a strategy to reducing their energy consumption by reducing the amount of water being pumped and treated in their jurisdictions. This work studies the pumping energy response of a distribution system when water conservation strategies are implemented in small geographic areas in the network. A water conservation plan is tailored to each defined area by specifying which conservation measures are feasible to implement, desired by the customer, and are attractive to the utility based on a potential return on investment in the form of reduced electricity bills to pump and treat water. Energy intensity and energy elasticity indicators are developed to assess the mechanical energy used in a network to distribute water to end-users. A case study for the City of Kingston water distribution system is presented. The distribution system studied indicated that when water conservation strategies produced marginal water savings, the energy response was inelastic to changes in water demand. The amount of energy required to move one cubic metre of water through the network increased with higher water savings because the percent savings of water was higher than the percent savings of pumping energy.