Metal Products Processor

A Brisbane manufacturer delivers a range of metal processing services, such as cutting, folder, counter sinking and drilling. The manufacturer recently moved to a new site with state-of-the-art LED lighting and controls and a very large solar system of 815 kilowatts (kW). This system currently has unutilised generation capacity which will service the business as it grows.

Through an energy assessment, five new energy saving and emissions reduction measures were found which would reduce energy consumption by 467 gigajoules (GJ) per annum and reduce emissions by 73.5 tonnes of carbon dioxide equivalent (t CO₂-e). Most of these measures have fast payback periods, ranging from instant to 2.2 years, with the exception of a battery storage option which offers a payback period of 7.3 years.

Summary of Opportunities

Utilise Lighting Controls

The site’s lighting is provided by new LEDs that can be controlled by the previously installed daylight sensors. These sensors respond to the amount of ambient light available through the building’s skylight. This would also allow the site to automate the operation of lighting on Sundays, when there is no production.

When the hardware for the sensors was installed, the software was not set up, so the sensors haven’t been in operation. A site engineer familiar with the software could likely configure it.The recommended option has not capital cost to implement and would deliver instant payback. It would deliver significant energy saving of 101 GJ a year and a reduction of 22.7 tonnes of CO₂-e.

Reduce Compressed Air Pressure

The site’s Atlas Copco compressors are currently operating at 7.5 bars, which is higher than the minimum required pressure of hand tools and production machinery found on site. It’s estimated that the pressure could be reduced to 6 bars without any operational impact. This $5,000 project has a favourable payback period of 1.1 years and would save 86 GJ of energy each year. A compressed air leak survey is recommended to ensure all unnecessary pressure drops are eliminated.

Compressed Air Leak Survey

During the energy assessment, compressed air leaks were audible. Leaks make up a constant baseload of compressed air demand and a significant amount of site energy costs. It’s estimated that leaks contribute 10% of the site’s compressed air energy consumption. This option would deliver 78 GJ of energy savings each year and reduce emissions by 17.7 t CO₂-e.

Batteries to Make Use of Excess Solar

Due to the large portion of , a battery system can be installed. This will increase the site’s utilisation of renewable electricity, reduce overall energy costs and improve the site’s environmental performance. Two potential battery sizes were evaluated using different desired outcomes:

• Size the battery such that the curtailed energy production from the solar PV system is minimised. This option would be sufficiently large to provide a significant amount of demand savings and potential demand response revenue.
• Size the battery to optimise financial returns and simple payback period.

The option that maximises returns is recommended for the manufacturer. This is a smaller 75 kW/15 kWh battery and the project would have a capital cost of $112,500 and payback period of 7.3 years. This option would improve the site’s energy and environmental performance with substantial annual energy savings of 162 GJ and more than $15,000 in cost savings.

Battery Powered Tools

The site uses a number of air driven hand tools for production and painting. Electric hand tools are more efficient than compressed air and should be considered as replacements. If the battery charging station is correctly controlled to only charge when there is excess solar production, it will utilise energy that will otherwise be curtailed. This project has a fast payback period of 0.7 years and a capital cost of $1,500. It would reduce energy usage by 39 GJ a year and cut emissions by 9 CO₂-e.