Reducing Energy Costs at a Queensland Dairy Farm

Overview

A dairy farm in Queensland sought to optimise its irrigation system and reduce energy costs associated with water extraction from the Mary River. The farm relied on a 45kW Davey mixed flow pump to irrigate using a centre pivot, travelling gun, and standpipes. A Type 3 Energy Audit conducted by Saturn Engineering Group identified inefficiencies in the irrigation system and provided tailored energy management opportunities (EMOs) to enhance efficiency and reduce costs.

Challenge

The farm consumed 106,262.5 kWh of electricity during the 2023/24 financial year, costing $40,687.58 under SAC Small Business Tariff 20. The 2023 year consumed 161,470.1kWh due to the additional irrigation requirement for the season. The audit revealed that the pump was operating inefficiently, with energy usage rates of 6.53 kWh/ML/m head for the travelling gun, 5.37 kWh/ML/m head for the centre pivot, and 6.16 kWh/ML/m head for the standpipes. High water velocities in sections of 100mm pipes increased friction losses, significantly adding to energy consumption. Additionally, the pump’s performance parameters were not matched to the irrigation system’s requirements, further reducing efficiency.

Proposed Solutions

  • Replacing 100mm pipe sections with 150mm pipe would reduce friction losses, lowering energy consumption. For the travelling gun, energy usage would drop from 589 kWh/ML to 465.7 kWh/ML, a 20.9% reduction. Similarly, standpipes would see a reduction from 556.3 kWh/ML to 438.8 kWh/ML, a 21.1% improvement.
  • Estimated capital cost: $25,000
  • Electricity savings: 14,900.5 kWh annually (14% reduction)
  • Cost savings: $5,625.10 per year
  • Payback period: 4.4 years with a 22.5% return on investment
  • Replacing the existing pump with one designed for the irrigation system’s specific requirements would optimise performance. This upgrade would reduce electricity usage for the travelling gun to 267.6 kWh/ML (54.6% reduction), the standpipes to 242.3 kWh/ML (56.4% reduction), and the centre pivot to 282.0 kWh/ML (5.4% reduction).
  • Estimated capital cost: $100,000
  • Electricity savings: 41,235.9 kWh annually (38.8% reduction)
  • Cost savings: $15,566.98 per year
  • Payback period: 6.4 years with a 15.6% return on investment
  • A 30kW solar system was evaluated using the 2023 energy consumption data but deemed unsuitable at this stage, as self-consumption would not sufficiently reduce electricity usage below the 100MWh threshold required to maintain SAC Small Business Customer Tariffs. A solar system could be revisited after implementing the pipe and pump upgrades to ensure it complements other improvements.

Results

Implementing both the pipeline replacement and pump upgrade would result in:

Conclusion

This energy audit provided practical and cost-effective recommendations to optimise irrigation efficiency and reduce energy costs. The pipeline replacement and pump upgrade offer substantial savings and improved system performance, laying the foundation for future energy initiatives such as solar integration.

Key Takeaway

By addressing inefficiencies in irrigation systems, farms can achieve significant cost and energy savings while improving operational efficiency. Saturn Engineering Group remains committed to helping agricultural businesses implement tailored, sustainable energy solutions.