A recent energy audit showed how improving the current systems can lead to energy and cost savings. The recommendations explored in the audit included replacing the 30kW pump with a new one including VSD, adding VSD to two existing pumps, and install a 12kW solar PV system. The farmer has implemented the VSDs and pumps replacement solutions, with estimated energy savings of 12% and emission reductions of 22.8 tCO2-e per year. The measurement and verification process is expected to be completed on the new irrigation system in the coming months.
Energy Savers
Summary
The farm, near Laidley, is a large producer of vegetables and has a large packing shed. The farm is irrigated year-round depending on rainfall. Water is supplied from on-site irrigation dams and is replenished from bores and rainfall. The irrigation systems are gradually being changed from high-pressure systems to drip tape to be more water-efficient and as a result, there is a variety of pressures required.
It is a large site consuming approximately 234,000 kWh per year at a cost of $53,000, irrigating over 70 hectares and harvesting 4200T of vegetables per annum. The farm has already installed a 100kW solar system.
The infrastructure contributing to the energy consumption onsite consists of:
- A 30kW centrifugal pump
- An 11kW submersible pump
- A 22kW centrifugal pump
- 2 large cold rooms totaling 53kW of cooling
A recent energy audit showed how improving the current systems can lead to energy and cost savings. The energy audit recommended the following changes to improve efficiency and reduce costs:
- Replacing the 30kW pump with a new pump with a VSD, to allow for accurate adjustments of irrigation pressure and reduce electricity consumption.
- Adding a VSD to the 11kW submersible pump.
- Adding a VSD to the 22kW pump.
- Installing a 12kW ground-mounted solar system at the site of the 11kW submersible pump.
Table 1. Energy and cost savings from audit recommendations
| Recommendations | Annual Energy Savings (kWh) | Annual Cost Savings ($) | Emission Savings (tCO2-e) | Capital Cost ($) | Payback Period (years) |
| 30 kW pump replacement with VSD | 11,000 | 3,000 | 8.9 | 19,000 | 6.3 |
| VSD on 11kW pump | 12,400 | 3,300 | 10 | 8,800 | 2.7 |
| VSD on 22kW pump | 4,750 | 1,000 | 3.8 | 8,000 | 8 |
| 12kW solar system | 13,900 | 4,100 | 11.3 | 21,600 | 3.4 |
| Total | 42,050 | 11,400 | 34 | 57,400 | 5.1 |
The grower has proceeded with the installation of the new pump and the 3 VSDs, with estimated energy savings of 12% over total farm consumption, cost savings of 14%, and carbon emission reductions of 22.8 tCO2-e per year. Actual savings will be updated once the measurement and verification process is complete.
Table 2. Pre and post implementation energy consumption, costs, and energy productivity improvements.
| Metric | Pre-Implementation | Post-Implementation | Reduction (%) |
| Energy Consumption (kWh) | 234,000 | 205,850 | 12 |
| Cost ($) | 53,000 | 45,700 | 14 |
| Energy Productivity (kWh/tonne) | 56 | 49 | 12 |
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.
