Beef Products Processor

A Gold Coast food manufacturer is a large energy user, consuming more than 27,000 gigajoules (GJ) of electricity and natural gas in 2019.  An energy assessment recommended a range of solutions to cut the producer’s electricity costs and improve its energy and environmental performance.

The potential savings are impressive, with 8,870 GJ in annual energy savings identified and $100,000 in annual cost savings. More than 330 tonnes of carbon dioxide equivalent (t CO₂-e) would also be saved under these measures.

Summary of Opportunities

Warehouse Lighting Upgrade

The beef producer has already commenced changing out high bay lights with LEDs and there remains 75 400 watt (W) high bay lights on site. A lighting layout redesign would mean that these could be replaced with 200 W LED high bay light replacements at a cost of $33,750, with a simple payback period of two years. This would achieve almost 80 megawatt hours (MWh) per annum in energy savings and save 64.4 t CO2-e.

Temperature Zone Separation

The ambient, cold and very cold zones within the site are currently not well isolated from each other during working hours due to high foot traffic and relatively small entryways between the areas.

Three air curtains (high velocity air) could be introduced between the zones with open entryways to act as a thermal barrier, reducing the refrigeration electrical load. This recommended option would also require installation of open door alarms to sound when insulating doors are left open.

At an estimated cost of $15,000, this would offer an 8.3-year simple payback period and energy savings of 11.2 MWh per annum.

Variable Pressure Control

Power consumption of refrigeration compressors is higher than necessary, as the head pressure (condensing temperature) is set high enough for the plant to cope with the hottest conditions it’s likely to face throughout the year. By installing variable speed drives (VSDs) on the condenser fans, the site would achieve substantial annual energy and cost savings of 227.7 kWh and $36,792, respectively.  It would also offer a significant cut in CO₂-e of 184.4 tonnes.

Refrigeration Heat Recovery

This recommended option is intended to reduce gas consumption by using hot water generated by heat recovered from the refrigeration plant. This heat is recovered to the site’s hot water loop to preheat water to between 50 to 60 degrees. With a payback period of only 2.8 years, this project would save the beef producer $24,324 in operating costs each year and save 1,749 GJ a year of natural gas.

Heat Pump Hot Water

Heat pumps are an effective and energy efficient way to create hot water using an electrical energy supply source instead of combusting natural gas. They work by absorbing heat from a source and transferring it to a refrigerant liquid, which is compressed to increase the temperature further. Using electricity instead of gas presents a pathway to zero emissions in the future.

This option currently presents a high capex ($80,000) and significant payback period (19.9 years), making it unfeasible for the manufacture at this time. This option could be revisited, however, if the heat pump system was integrated into the site’s existing refrigeration system, allowing the heat pump to be a water sourced machine, where heat is taken from a water stream to produce chilled water. This means the heat pump would be used in two processes –refrigeration and industrial heating (up to around 90°C).

In these situations, heat pumps can have paybacks of less than five years without government incentives. The factors that significantly affect heat pump returns include:

• Gas price needs to be high – at $15/GJ or higher.
• Electricity prices need to be low at less than $0.20/kWh.
• Sites that have excess capacity for new electrical loads. This can often be achieved by removing excess refrigeration plant (as the heat pump would be used to supplement cooling).
• Site’s with an inefficient heating system (e.g. using steam to heat air for drying).

Power Factor Correction

Another option for consideration is the installation of a power factor correction unit that would increase the mean power factor for the site from 0.87 to 0.98. This may be beneficial as bringing the power factor closer to unity would bring down the demand charges. This option would cost $126,000, with potential annual savings of $14,160.

To be added as feature/call-out box

Cutting Energy Use and Emissions with a Solar PV System

Electricity accounts for 93% of the site’s energy costs. With the installation of two solar photovoltaic (PV) systems (one for each NMI), the beef producer would realise substantial energy cost savings and reduce its greenhouse gas emissions significantly. The two systems are described below.

• A large 250 kW system – this is intended to meet the maximum site load while also returning a positive net present value, and reasonable simple payback. Large-scale generation certificates (LGCs) could be obtained for this system.
• A smaller 99 kW system on the site’s secondary NMI – this would meet a substantial part of the NMIs load and avoid any export to the grid (as only 5% of total generated output can be exported). This system can take advantage of small-scale technology certificates (STCs).

Both options are recommended. The larger system would meet emissions reduction and energy saving objectives, while delivering cost savings of $55,892 a year and GHG emissions savings of 305.4 t CO₂-e. The 99 kW system, with its lucrative STC rebates and $21,572 in annual cost savings, has a favourable business case and would also save 120 t CO₂-e.