The farm consists of 214 ha which are irrigated all-year-round producing 79 units per ha per year. Variability in energy consumption is strongly influenced by rainfall and annual variation of growth periods and temperatures. As the farm is planning to expand, production and electricity requirements are expected to increase. 

The annual energy consumption for the site during the 2018-2019 period was 1,800,000 kWh at a cost of around $494,000. 

The energy consumption on the farm consists of: 

• Irrigation: 8 pumps including booster, bore, and centrifugal units, with diverse water sources and interdependencies that had created a complex set of irrigation schedules. Some pumps have already been fitted with a timer to optimize their use.
• Other minor uses: an office, a shed, pump backwash, and controls.  

A recent energy audit showed how improving the current systems can lead to energy and cost savings. The audit recommendations are: 

• Tariff Change: change from transitional tariff 66 that will be phased out during 2021, to a more cost-effective option (T50) on one larger user pump. For this, installation of smart metering is recommended, given it is a ‘time of use’ tariff. This device has an average installation cost of $1,000 and will allow the business to understand their energy consumption, for better demand management and reduce potential demand charges. Read more about that HERE. 
• A 39kW Grid Connected Solar PV: install a 39kW solar system with a 30kW inverter to offset the energy required by one of the pumps. Although the energy consumption for irrigation is higher, the PV system has been designed to match the pumps’ energy consumption throughout the year to ensure its profitability, considering 61% onsite utilization and 39% exports. The inverter capacity has been capped at 30kW to avoid the additional connection charges on systems over 30 kW.  
• Pump Upgrade: installation of a 55 – 75 kW booster pump with VSD to increase the pumping volume and achieve a greater distance, avoiding double pumping and reducing water and energy losses through direct supply and improvement of flow rate. 
• Smart Water Metering: installation of meters on the 3 main irrigation systems to assist in irrigation scheduling through increased visibility of water consumption patterns. 

The auditor also identified some preventive management measures at no cost, focused on maintaining the consumption of 2 pumps below 100,000 kWh per year, avoiding large consumer demand charges for these equipment’s, as follows:  

• Constant verification of consumption using smart water metering devices. 
• Sprinkler walkthrough of key areas and review filter cleaning schedules when performing flow tests. 

Table 1. Costs and savings from audit recommendations. 

The grower has proceeded with the replacement of the booster pump, achieving energy savings of around 23,477 kWh, which have been estimated from a Measurement and Verification (M&V) process. The M&V analysis has not been comprehensive as it was based on only 3 months of available post-implementation data on energy and water consumption. This analysis should be strengthened with 9 months of additional data to have a full year of comparable period assessed, being able to calculate the savings from the solution implemented with better accuracy and the efficiency of the irrigation system.  

Therefore, by replacing the booster pump the farm has reduced annual energy consumption by approximately 35% for the pumping system and 1.3% for the whole farm. 

The grower is happy with the booster pump and is still working on assessing more energy-saving opportunities.

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.