Operational energy-efficiency improvement of municipal water pumping in California

This paper implements a normalization/regression-based approach to estimate the kWh energy and kW savings from an experimental OEEP (operational energy-efficiency program) for municipal water pumping in California. The voluminous 1-min data collected in the course of the OEEP presents a unique opportunity to analyze how VSD (variable-speed drive) technology aided by a PLC (programmable-logic-controller) may improve municipal water pumping's operational energy efficiency. Our proposed approach enables a comparison of pump operations with and without the OEEP, yielding accurate estimates for kWh energy and kW capacity savings that are useful in evaluation, monitoring, and verification of the program. Our findings lead us to conclude that (a) variability of efficacy by analyzed pump sites suggests targeted implementation of the OEEP; and (b) for a correctly-sized pump operating near its optimal kW-output value, adding a VSD and PLC can actually harm the pumping system's overall energy-efficiency. ► Use of VSDs (variable-speed drives) at pump sites may improve efficiency and lessen energy and demand costs. ► A normalization/regression approach enables accurate assessment of VSD performance. ► Variability of efficacy suggests targeted implementation of the OEEP (operational energy-efficiency program). ► Adding a VSD-PLC (Variable-speed drive – Programmable-logic-controller) to an optimally-sized pump can harm overall energy efficiency.