Poultry Products Manufacturer

A South East Queensland food product manufacturer is a large energy user, consuming more than 61,000 gigajoules (GJ) of energy in 2019.  Through an energy assessment, it was found that the site could realise substantial annual energy and cost savings (up to $419,00 per annum) through energy efficiency projects. The largest of which offers savings of 6,092 GJ and $119,00 each year.

Through installation of a large solar PV system, the site could also reduce its emissions by 1,319 tonnes of carbon dioxide equivalent (t CO₂-e) and cut its annual operating costs by more than $200,000 per annum.

Summary of Opportunities

* Only one of the first three options can be selected (they cannot be combined)

Steam Boiler Upgrades

The site’s two existing steam boilers are both nearing the end of life. Neither boiler has been upgraded with modern controls or energy saving measures. Upgrades to the existing boilers that would achieve energy and cost savings (773.6 GJ and $16,655 per annum, respectively) and reduce greenhouse gas emissions by almost 40 t CO₂-e.

The measures are:

• Variable speed drive (VSD) on blower fan and electronically actuated gas valve – allows highly accurate control of the air / fuel mix resulting in a more efficient and cleaner burning flame in the burner chamber
• Flue / feed economiser – a shell and tube heat exchanger installed in the boiler flue to recover lost heat from the boiler flue gases and return that heat to the feed water. This means that the feed water requires less energy from gas to reach its boiling point.
• Oxygen trim – trimming the oxygen to the optimal level as high levels of oxygen in the flue means extra cold is being blow into the burner chamber.

Should the manufacturer choose to replace the existing boilers, the above measures could still be implemented with similar energy saving effect.

Steam Boiler Replacement with Condensing Water Boilers

Over 85% of the site’s steam goes to the hot water exchangers to generate hot water. This is much more energy intensive than making hot water directly.

Installation of three condensing boilers to replace the two existing steam boilers would provide the site with a similar amount of hot water for less energy and offer a more robust option should there be a failure of one unit. Condensing units are much more efficient than traditional boilers.

This option has a capital cost of $250,500 with a positive payback period of under five years, and offers gas savings of 2,321 GJ per annum. It would have a significant effect on emissions, reducing them by more than 119 t CO₂-e.

Air Sourced Heat Pumps

Air sourced heat pumps are an effective and efficient way to create hot water using an electrical energy supply as compared to combusting liquid petroleum gas (LPG). The benefits of this technology are that electricity can be sourced renewably, offering a pathway to zero emissions, and the thermal energy is made more efficiently per unit of energy input. Given the heat pumps have a higher capex than steam /water boilers, this option recommends replacing half of the hot water generation with heat pumps.

The project’s $380,000 capital cost would be paid off in 3.9 years and would save the manufacturer $105,470 per annum. Without the use of renewable energy, this option would increase greenhouse gas emissions, however, if the site was to partially source electricity from renewable sources this would present a significant potential for decarbonisation.

Replace Tub Washer Steam with Electric Heating

A steam sterilisation process is used to eliminate bacteria from plastic tubs so that the tubs can be reused. Currently, the tub washer is the only direct user of steam on site. To improve efficiency and lower operating costs, it’s recommended to use electrically-sourced hot water through a heat pump or via electrical induction heating as a steam-free alternative for the sterilisation process. A small heat pump has been selected as this would result in more energy savings and therefore is recommended. This option would deliver annual energy savings of 2,150 GJ and cost savings of $37,401. Its capital cost is $220,000 and payback period of 5.8 years.

Insulation / Lagging on Hot Pipes

Using a thermal imaging camera, significant heat losses were detected from the thermal energy sources on site. This showed a significant amount of uninsulated pipework, especially around the back area of the boiler house.

Insulating hot pipes with rockwool insulation and aluminium cladding, and using flexible insulated jackets over valves, will save significant heat losses at this site, resulting in less steam having to be generated in the first place. This affordable option has an $11,920 capex and payback period of 2.4 years. It would save the site more than 249 GJ of energy each year.

Heat Recovery from Refrigeration System

A facility with both refrigeration and hot water requirements can benefit from heat that would otherwise have been rejected from the refrigeration plant. Instead of sending rejected heat to the plant’s condensers, the heat could be recovered to the site’s hot water loop to preheat water. This provides a considerable saving in LPG consumption.

This would be achieved by installing a discharge gas de-superheating heat exchanger, heat recovery oil coolers on. Both screw compressors, a large storage tank and associated pumps and pipe-work. The capital cost of this energy investment is $259,000, with a five-year payback period. Almost 130 t CO₂-3 would be saved annually, and about 2,501 GJ.

To be added as feature/call-out box

Solar PV Drives Down Energy Costs and Emissions   

A 1,200 kilowatt (kW) roof top solar is recommended as the optimal solar PV option for the site. This maximally sized system would reduce the site’s electricity related emissions while still making a financial return. This system would take advantage of large-scale generation certificates (LGCs), with rebates of $292,177 available, and would cut emissions by an impressive 1,319 t CO₂-e each year. While the capital cost is significant at over $1.5 million, $202,122 would be saved each year, resulting in payback period of 6.2 years.

Another feasible option is available to the manufacturer – a 99 kW solar system. This system would have a five-year payback period, with annual cost savings of $19,294. While this a cheaper option, it was not recommended through the energy assessment as the energy and emissions saving offered by the 1,200 kW option is substantially greater.