Application of Energy Auditing Procedures to Reduce Operational Costs at Flour Mills of Nigeria, Apapa, Lagos

This study applies systematic energy auditing procedures to identify and quantify electricity cost reduction opportunities at the Flour Mills of Nigeria facility in Apapa, Lagos, South West Nigeria. Manufacturing facilities in Nigeria's food processing sector operate under significant cost pressure from high electricity tariffs and unreliable grid supply that forces reliance on expensive self-generated diesel power, making energy efficiency a critical competitive factor. A detailed energy audit was conducted following the ASHRAE Level II audit methodology, encompassing a review of 24 months of electricity billing data, walk-through inspection of all electrical systems, power quality measurements at major load centres, motor efficiency testing, compressed air system leak detection, and lighting level assessments. The audit identified the milling motor drives, compressed air generation, and facility lighting as the three largest energy end uses, collectively accounting for 81 percent of total electrical energy consumption. Variable speed drives were absent on seven milling motors operating at fixed speed, representing a significant efficiency improvement opportunity. Compressed air leak survey identified losses equivalent to 18 percent of compressor output. Lighting in warehouse areas consists entirely of high-pressure sodium fixtures with significantly lower efficacy than LED alternatives. Implementation of variable speed drives on identified motors, compressed air leak repair, and LED lighting retrofit is projected to reduce total electrical energy consumption by 23 percent, with an aggregate investment payback period of 2.1 years. The study provides a prioritised, costed implementation plan for the facility engineering management team. Keywords: energy audit, industrial energy efficiency, flour mill, variable speed drive, Lagos.