Derivation and Use of the Pump Energy Intensity Equation for Water System Energy Analysis
Rob Sowby and Kai Krieger
Energy intensity—an expression normalizing pump energy use by water volume—is becoming a more commonly used key performance indicator as water utilities seek to analyze and optimize their energy use. Its theoretical basis, however, has not been well documented. Beginning with Newton’s second law, we derive the pump power equation and the pump energy intensity equation, provide specific values for engineering reference, and discuss applications. In a perfectly efficient system pumping water, the minimum energy intensity is 0.00272 kWh/m3 per meter of head or 3.14 kWh/Mgal per foot of head.