Electric Cabling Producer

A South-East Queensland electric cabling manufacturer has a 24 hour, 5 day a week operation that relies on grid electricity. Five energy and emissions conservation measures were identified which found 1,744.8 gigajoules (GJ) of energy savings per annum, annual cost savings of $78,994 and an emissions reduction of over 392 tonnes of carbon dioxide equivalent (t CO₂-e). These energy saving measures include lighting improvements, improved motor efficiency, variable speed drives and repairs to the compressed air system.

The site has two separate mains electrical meters, allowing for installation of two solar PV systems -  one 99 kilowatt (kW) system and a larger one of 250 kW.

The combined annual energy savings would be more than 700 GJ per annum and emissions reduction of 157.6 t CO₂-e.

Summary of Opportunities

Upgrade Remaining Metal Halide Lights to LED

The manufacturer has replaced the metal halide lights for LEDs in the main production hall; however, the secondary production area has at least 20 x 400 watt (W) metal halide high bay lights remaining. It is expected that these could be replaced with a similar number of 200W LED high bay lights to achieve cost and energy savings.

The site should prioritise those lights that are used throughout the night during the week. High-quality LEDs should be selected, particularly as these lights will need to function in a hot ceiling space through Queensland summers and be protected against metal swarf. Replacing the LEDs will reduce the site’s emissions by 23.3 t CO₂-e and save 103.3 GJ of energy a year. The project offers a favourable payback period of 0.8 years.

Daylight Sensing Lighting Controls

A further lighting improvement has been identified that would deliver 67.4 GJ of energy savings a year. The site currently uses lights during the day, despite having sufficient light on sunny days through the existing sky lights. An automatic method of turning lights off during bright daylight would reduce the chance of human error (of not turning the lights off) and ensure the site always meets the minimum levels of lighting required for safe operations.

By installing four daylight sensors in suitable locations within the main production hall, the site could save $3,051 in energy cost savings a year, delivering a payback period of just 1.1 years. Alternatively, more expensive LEDs with inbuilt daylight sensors could be sourced, particularly for the secondary production area that has the remaining metal halide lights.

Motor Efficiency Rating Upgrade (EOL)

Large motors are the primary electricity loads for the manufacturer. Most of the motors currently have an efficiency rating of IE2. The efficiency rating provides the required minimum efficiency level in each rating class. By increasing the motor class from its current IE2 rating to a higher class, better motor efficiency is guaranteed. For the manufacturer, this would require the purchase of new motors, which is unlikely to be feasible unless the motors are at end of life.

The recommended project is to replace the nine largest IE2 rated motors at their end of life with the most efficient IE class available for these motor sizes - the IE5. This project would achieve significant energy savings of more than 640 GJ per year and annual cost savings of $29,000. Emissions reduction from this project would be 144.1 t CO₂-e.

Cooling System Variable Speed Drives (VSDs)

Cooling water is required for many of the site’s machines in order to remove heat generated when working with metal. The cooling water is generated by pumping water through an evaporative cooling tower and then pumping the water through several loops to each of the machines.

There is an opportunity to install VSDs into each of the pump motors and the condenser tower to reduce the motors’ speeds so that only the required cooling water is supplied. The project would require temperature sensors, VSDs retro-fitted on each motor, a small programmable logic controller (PLC) or VSDs with direct sensor inputs.

The business case for this option is favourable with a payback period of 0.7 years and annual energy cost savings of $30,060. It would cut emissions by almost 150 t CO₂-e and produce energy savings of 664 GJ a year.

Compressed Air Leak Survey

An ultrasonic leak survey and effort to reduce waste compressed air usage would result in significant savings. Multiple small leaks were identified during the assessment and reducing air leaks would likely enable the site to reduce the pressure set point of the system from the current 7.2 bar to the minimum operating pressure. At a capital cost of $14,405 and with annual energy cost savings of $12,205, this project would have a payback period of one year. It would reduce energy and emissions by 269.9 GJ a year and 60.7 t CO2-e, respectively.