Implementation of an Energy Management System for Reducing Electricity Costs in a Steel Rolling Mill in Delta State

Steel rolling mills are among the most energy-intensive industries in Nigeria, and operations in Delta State, South South Nigeria, face compounding cost pressures from high electricity tariffs and diesel generator operating expenses due to grid unreliability. This study presents the implementation of an energy management system at a medium-scale steel billet rolling mill in Warri, aimed at systematically reducing electricity consumption and improving energy cost efficiency. The EMS architecture includes power quality analysers installed at main distribution panels, sub-metering at individual motor control centres, and an energy monitoring software dashboard integrated with the plant's existing SCADA system. Baseline energy intensity was established at 385 kilowatt-hours per tonne of rolled product over a three-month pre-implementation measurement period. Following EMS implementation, energy efficiency opportunities identified included off-peak demand shifting for reheat furnace preheating, motor speed optimization using variable frequency drives on rolling mill auxiliaries, and elimination of compressed air leakage. Implementation of the VFD upgrade on four major auxiliaries, demand management scheduling adjustments, and compressed air system repair were executed over a six-month project phase. Post-implementation energy intensity was measured at 314 kilowatt-hours per tonne, representing an 18.4 percent improvement. Annual energy cost savings were estimated at 47 million Naira based on prevailing electricity tariffs. The study provides an energy management implementation guide applicable to other energy-intensive manufacturers in the Niger Delta. Keywords: energy management system, steel rolling mill, VFD, energy efficiency, Delta State