Of the energy-saving opportunities evaluated, two initiatives were implemented with potential energy savings of 16%, a combined payback period of 20 years, and carbon savings of 16.2t CO2-e. The recommendations implemented included replacing 4 refrigeration units to better manage redundancies in the system and replacing the evaporator fans to improve efficiency and reliability, with a considerably long payback period given the seasonality of cooling requirements. The measurement and verification process is expected to be completed on the new refrigeration system in the coming months.
Energy Savers
Summary
The farm, in the Lockyer Valley, produces around 2,400T of tomatoes and is irrigated year-round depending on rainfall. Water is supplied from on-site irrigation dams which are replenished from bores and rainfall.
It is a large site consuming 123,000kWh per year at a cost of $26,000 in the NMI audited. A key target of the farm is to reduce the consumption of the NMI below 100,000 kWh per year to be considered a small customer and avoid demand charges with a suitable tariff choice. The farm already has a 70 kW solar system installed in the packing shed.
The infrastructure contributing to the energy consumption onsite consists of:
- 4 large cold rooms with units of unknown age, 2 rooms with rapid cool assistance;
- A packing shed area.
A recent energy audit showed how improving the current systems can lead to energy and cost savings. A detailed analysis of power consumption in the cold rooms was undertaken using real-time metering to identify energy-saving opportunities. The energy audit recommended the following changes to improve efficiency and reduce costs:
- LED Lighting upgrade in the packing shed.
- Replace evaporator fans with energy-efficient direct drive fans that can operate at different speeds, complemented with the controller upgrade to allow for the more complex fans.
- Replace the refrigeration units with a single refrigeration rack containing at least 3 compressors with the lead compressor on speed control.
Table 1. Energy and cost savings from audit recommendations
| Recommendations | Annual Energy Savings (kWh) | Annual Cost Savings ($) | Emission Savings (tCO2-e) | Capital Cost ($) | Payback Period (years) |
| LED Lighting Upgrade | 773 | 281 | 0.6 | 1,450 | 5.2 |
| Replace Evaporator Fans | 10,000 | 5,700 | 8.1 | 16,000 | 2.9 |
| Replace refrigeration units | 10,000 | 5,400 | 8.1 | 200,000 | 37 |
| Total | 20,773 | 11,381 | 16.8 | 217,450 | 19 |
The grower has proceeded with the installation of the new refrigeration units, fans, and control system. They will be installing 4 separate refrigeration units to better manage redundancies in their system and better control temperature requirements, with potential improvements in the quality and reliability of operations, which compensates for the long payback period as they have only been used for a few months per year. Measurement and verification will be completed on the new refrigeration system in the coming months.
By installing the recommendations in the audit, the business could have reduced energy consumption by 16% and costs by 43%, with carbon emission savings of 16.2 tCO2-e per year.
Table 2. Pre and post audit energy, costs, and energy productivity savings
| Metric | Pre-Audit | Post-Audit | Reduction (%) |
| Energy Consumption (kWh) | 123,000 | 103,000 | 16 |
| Cost ($) | 26,000 | 14,900 | 43 |
| Energy Productivity (kWh/tonne) | 51 | 43 | 16 |
With the refrigeration upgrades implemented, the farm is able to achieve the target of energy consumption on the assessed NMI below 100,000 kWh per year.
An energy audit is a good investment
An energy audit is a great first step in moving a business towards a more efficient future by reducing energy use, costs, and carbon emissions on site.
An energy auditor will review your past energy bills, your equipment, and the way your business operates. They’ll show you where you’re using excess energy and explain what you can do about it. Find out about what’s involved in an energy audit HERE.
See our range of agricultural energy efficiency case studies HERE and Subscribe to our bi-monthly energy e-news HERE
If you have any energy efficiency related questions for the team get in touch at energysavers@qff.org.au.
The Energy Savers Plus Extension Program is delivered by the Queensland Farmers Federation with support and funding from the Queensland Department of Energy and Public Works.
