The farm, near Gatton, annually produces around 9,500 tonnes of cabbage, cauliflower, and lettuce and is irrigated year-round depending on rainfall. Water is supplied from on-site irrigation dams and is replenished from bores.
It is a large site consuming 280,000 kWh at a cost of $60,000. One of the sites is a large customer consuming 120,000kWh. The current energy benchmarking is 30 kWh/tonne.
The infrastructure contributing to the energy consumption onsite consists of:
- 10 submersible bore pumps ranging in size from 1kW to 7.5kW on 3 separate NMIs, one with a VSD
- 37kW centrifugal dam pump with VSD
- 30kW centrifugal dam pump with VSD
- Machinery sheds
A recent energy audit showed how improving the current systems can lead to energy and cost savings. The energy audit recommended the following changes to improve efficiency and reduce costs:
- Installing Variable Speed Drives on the 9 submersible bore pumps over 3 properties. All the pumps are small (under 7.5kW) and have varying flow requirements according to the aquifer conditions. By installing VSDs the water levels can be better managed to prevent damage to the pump and reduce electricity usage from excessive throttling of the valves.
- Replacing 2 pumps with smaller models (from 7.5 & 5.5kW pumps to 4kW) with VSDs.
- A soil moisture monitoring system on one of the properties due to the location away from the main property. By having accurate readings of soil moisture, the grower will be able to prevent multiple trips to the other property and better manage irrigation scheduling with other personnel in the business. If this system is connected to the VSD of the corresponding pumps, irrigation can be programmed to pump when the soil needs it, improving the efficiency of the system.
- Installation of a 15kW solar PV system to offset energy consumption for irrigation.
Table 1. Energy and cost savings from audit recommendations
||Annual Energy Savings (kWh)
||Annual Cost Savings ($)
||Emission Savings (tCO2-e)
||Capital Cost ($)
||Payback Period (years)
|3x VSDs and 2 new pumps site 1
|2x VSDs and monitoring system site 1
|4x VSDs site 2
|15kW Solar System
The grower has proceeded with the installation of the 9 VSDs and the replacement of 2 pumps, while solar and soil moisture monitoring will be considered in future upgrades to minimise travel times between properties and better manage water resources.
By installing the recommendations in the audit, the business has estimated a reduction of energy consumption by 42% and costs by 50%, with carbon emission savings of 95.6 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
|Energy Consumption (kWh)
|Energy Productivity (kWh/tonne)
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 email@example.com.
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.