Steel Fabricator

An energy assessment for a Cairns steel manufacturer was undertaken to identify energy and emissions reduction opportunities. The site is powered by electricity, with the exception of six forklifts and a few small generators. The site’s electricity consumption was 2,059 gigajoules (GJ) of energy in 2020, and electricity-related emissions totalled of carbon dioxide equivalent (t-CO₂-e).

Five energy and emissions conservation measures were identified for the site, at a combined capital cost of $35,600 and simple payback period of just 1.5 years. The energy savings and emissions reduction opportunities identified are significant - 422 GJ of energy and 95 tonnes of t-CO₂-e.

Summary of Opportunities

Compressed Air Solutions

Air compressors represent 18% of the site’s total energy consumption. Three compressed air energy saving opportunities were identified through the site’s energy assessment. These are:

• Compressed air leak survey - Compressed air leaks are estimated to contribute to 25% of the site’s compressed air energy consumption. Many leaks were observed to be on old tubing plastic push in fittings. A compressed air leak survey and subsequent repairs is recommended, using an ultrasonic leak detector to identify the leaks. This project would have a payback period of 1.8 years, and the savings would be significant, with 92.6 GJ in energy savings per year and $3,082 in annual energy cost savings.
• Compressed air reticulation system improvement - The compressed air reticulation system has been added to over the years as new steel fabrication equipment is brought online, with several of the machines requiring high pressure compressed air to operate. This has resulted in the two smallest air compressors operating at high load and unload setpoints of 9 and 10 bars, respectively.

It’s recommended that two ring mains are created–one for the high-pressure lines (for the smaller air compressors) and the other for a large VSD compressor. This would allow the three machines to operate at lower load and unload setpoints, reducing the site’s energy consumption by 38.9 GJ per year and emissions by 8.8 t CO₂-e. This option has a 1.4-year payback period.

• Compressed air hand tool replacement - Many hand tools on site currently use compressed air to operate, which is an inefficient method easily replaced by electric alternatives. Low cost alternatives are available which would offer a fast payback period of 0.3 years and reduce the site’s compressed air load. This option would realise total cost savings of $1,798 and energy savings of 27.8 GJ per year.

LED Lighting Upgrade

Many high bay and fluorescent lights at the site can be replaced with LED lights. LED lighting technology has improved in recent years in terms of quality, reliability, lifetime and cost. The lighting project would be eligible for ACCUs under the Federal Government’s Emissions Reduction Fund. 

While the capital cost of $19,000 is higher than some of the recommended options, the payback period is only 1.5 years and it offers substantial annual savings of $12,172 and 263 GJ of energy.

Electric Forklift Replacement

The site’s forklift fleet is currently diesel powered and three of the five forklifts are close to reaching end of life. Recent advancements in electric vehicle and battery technology is driving down the cost of alternatives to standard fossil fuel powered equipment, such as forklifts.

It is recommended that the manufacturer invest in three electric forklifts as the ageing fleet is retired. This will reduce energy costs and align with greener energy sources. To be commercially viable, fleet replacement should be staged.

The project would increase electricity demand; however, this is far outweighed by the energy savings that would be realised when the diesel forklifts are retired. The net energy savings would be 526.2 GJ per year, which is the highest energy savings of all the recommended options. The project has a capital cost of $60,000, with a simple payback of four years. The payback could be reduced to three years if the electric forklifts are charged in summer outside of peak times to reduce demand charges.

Batteries for Demand Reduction

A 50 kilowatt (kW) / 100 kWh battery would provide annual cost savings of $7,277. Based on the current market price of batteries, this option would cost $90,000 to implement, making it financially uneconomical. Battery prices are changing rapidly, however, so the current use cases that are uneconomical will likely change in coming years. This option should be revisited at this time.