Energy Efficiency for Municipal Groundwater Systems

Nationally, water and wastewater treatment plants account for 4% of our electric energy use.  The Water Environment Federation (WEF) estimates that energy improvements can save from 15% to 30% energy costs at water and wastewater plants.

Municipal groundwater system may be a simple single pressure zone with a few wells, or a complex system with a dozen pressure zones and scores of wells.  Large wells can spend more than $100 K per year on energy, and some communities spend more than $2 M annually on groundwater pumping.  Implementing energy savings programs can save water customers money on their water bills, or can fund other critical infrastructure projects.

To estimate the potential energy savings for a groundwater system, the first step is to “benchmark” the water system energy usage.  Benchmarking compares your system’s energy use to similar systems.  If your groundwater system consumes more energy than similar systems, you have more potential for energy savings.  Benchmarking is a simple process and can be calculated by most energy engineers in few hours if they are provided energy bills, well operating information, and reservoir elevations.

If your groundwater system has a poor benchmarking score, the next step is pump testing using “water-to-wire” (W-to-W) efficiency tests.  The W-to-W efficiency tests determine if a pump is operating “off” its pump curve, and the attractiveness to replace the pump and/or motor.  Many other energy savings measures (ESMs) can be implemented to reduce energy consumption and/or costs.  Some more common ESMs are operating the most efficient well pumps first and most, operating wells and pumps at off-peak hours, implementing an automated demand response (ADR) program, changing energy accounts to a more attractive rate structure, operating reservoirs at reduced levels during the winter, and many others.