Specialist Food and Drink Manufacturer

More than 1,000 gigajoules (GJ) of energy a year could be saved for a specialist food and drink manufacturer through six energy and emissions conservation measures. This would reduce the site’s energy consumption by more than 15%. These measures would also cut the site’s emissions by 122 tonnes of carbon dioxide equivalent (t CO₂-e), accelerating decarbonisation efforts.

A 99 kilowatt (kW) solar PV system would achieve further energy savings of 401 GJ a year and reduce emissions by another 90 t CO₂-e.

Summary of Opportunities

Lighting Upgrade

All 500 lights at the site are old and would benefit from replacement. With a lighting layout redesign, these would likely be replaced with a similar number of LED lights. Some additional measures for consideration include:

• Prioritise the replacement of lights that run for the longest duration each day to maximise energy savings.
• Select high-quality LEDs, particularly if they are to be located above any sources of heat.
• Install occupancy sensors in areas with low occupancy.

This project is an opportunity for the site to reduce energy consumption by 232 GJ a year and reduce emissions by 52 tonnes of CO₂-e. At a capex of $55,935, the estimated payback period is eight years.

Compressed Air Leak Survey

Through an ultrasonic leak survey and an effort to reduce waste compressed air usage, the manufacturer could achieve energy savings of $1,907 and 47 GJ a year. Repairs to compressed air leaks would likely enable the site to reduce the system’s pressure set point to the minimum operating pressure. This project has a capex of $6,000 and a payback period of 3.1 years.

Boiler Oxygen Trim and TDS Sensor

Boiler efficiency has decreased over time due to incorrect fuel to air ratio. As a result, unburnt fuel is seen with excess oxygen in the flue stack. To detect this unburnt fuel and improve boiler efficiency, it’s recommended that an oxygen trim system is installed on each of the site’s boilers. This will measure the excess oxygen in the flue gas. The system also controls fuel and air to decrease the fuel loss and shift the boilers to their maximum efficiency zones.

A well-controlled blowdown control regime would help maintain low total dissolved solids (TDS) in the boiler and improve its performance. Measuring TDS can be done externally or by placing a sensor inside the boiler to detect TDS levels. In addition to the oxygen trim system, TDS sensors are recommended for each boiler.

This project offers the highest energy saving of any option considered at 407 GJ a year, a forecast capital cost of $185,000 and payback period of 13.3 years.

Heat Pumps

To reduce the site’s reliance on liquefied petroleum gas (LPG), it’s recommended that the manufacturer consider switching to electricity. A benefit of this is that electricity can be sourced renewably, offering a pathway to zero emissions.

One opportunity is to use a bank of industrial heat pumps, powered by electricity, to concentrate heat from various sources into a useful heat stream (in this case, water). Waste heat can be utilised from the site’s refrigerated containers outside to pre-heat water in the boilers, which can then be further converted to steam. For this site, a 200kW heat pump would be appropriate.

With a capital cost of $200,000 and energy savings of only $6,928 a year, this project would have a substantial payback period of 28.9 years. For this reason, this option should only be considered if further carbon emissions reduction is critical.

Shed for External Refrigeration Containers

The site currently has a very high cooling load due to its refrigeration, which is essential in stopping the produce from becoming spoiled. The site uses 3 x 20 ft refrigeration units, located outside the facility in direct sunlight. Building a shed around the containers would improve the cooling efficiency. This option would cost $42,525, with a payback period of 13 years, and would help to meet energy and emissions objectives, cutting greenhouse gas emissions by 23 t CO₂-e and saving 23 GJ of energy a year.

Variable Speed Drive (VSDs) on Chiller Pump

The pumping mechanism on the site’s chiller doesn’t have a VSD and instead uses an old valve to control the flow. It’s recommended that a 5 kW VSD is installed on the chiller pump to regulate the flow to meet the actual demand. VSDs provide operational benefits such as providing constant pressure outputs, ‘soft starts’ (minimising the surge that occurs when a motor starts) and reducing pump wear. This project is likely to reduce the pump’s energy consumption by about 8% (4 GJ per annum) and save one t CO₂-e.