A South-East Dairy farm has saved money, reduced energy consumption, and possibly improved productivity, after implementing the recommendations from a recent Energy Savers Audit. The farm implemented the recommended irrigation upgrades.
A South-East Dairy farm has saved money, reduced energy consumption, and possibly improved productivity, after implementing the recommendations from a recent Energy Savers Audit. The farm implemented the recommended irrigation upgrades.
The farm is 150 ha and irrigated all year round, producing around 8 units per ha per year.
The annual energy consumption for the site during the 2018-2019 period was 48,500 kWh at a cost of $15,500, with a solar thermal system already implemented used to pre-heat water and a 5kW solar PV system used by the irrigation system. The energy consumption on the farm consists mainly of:
A recent energy audit showed how improving the current systems can lead to energy and cost savings. The audit recommendations are:
Table 1. Costs and savings from audit recommendations.
Recommendation | Annual Energy Savings (kWh) | Annual Costs Savings ($) | Emission Savings
(tCO2-e) |
Capital Cost ($) | Payback Period (Years) |
Plate heat exchanger | 3,927 | 1,072 | 3.2 | 7,500 | 7 |
Lobe vacuum pump with VSD | 6,844 | 2,395 | 5.5 | 20,000 | 8 |
Reconsider milking machine wash program | 7,516 | 1,984 | 6 | 0 | 0 |
Review electricity meters and tariff pricing | – | 2,300 | – | – | 0 |
Investigate and fix the pump | 7,401 | 1,954 | 6 | 4,000 | 2 |
Investigate and eliminate head losses | 1,885 | 498 | 1.5 | 3,000 | 6 |
Replace irrigation system with a solid set | 1,261 | 5,894 | 1 | 36,000 | 6 |
Solar PV system | – | 2,300 | – | 15,000 | 7 |
Total | 28,834 | 18,397 | 23.2 | 85,500 | 4.5 |
The farmer replaced the travelling gun irrigator with a solid set system. The savings made have been measured in a Measurement and Verification (M&V) process, as outlined in Table 2.
Table 2. Estimated and Actual energy and cost savings.
Metric | Audit estimation | M&V calculation | Variation (%) |
Energy Savings (kWh) | 1,261 | 532 | -58 |
Cost Savings ($) | 5,894 | 5,700 | -3 |
The lower energy savings obtained from the M&V calculations compared to those estimated in the audit have been influenced by different assumptions on the use of water by the irrigation system. The audit used the same volume of water measured to estimate the energy savings of the proposed solution, while the M&V used a conservative calculation since the upgraded system requires less water to irrigate the same area (3.1 ML instead of 5.5 ML).
The increased watering efficiency has been caused by the increase in pump efficiency from 48% to 53.9% when changing the section from hard hose to solid set irrigation.
The production benefit from the irrigation system upgrade outweighs the cost of increased energy consumption with an increase in revenue. The travelling gun system had a Distribution Uniformity (DU) of 49%, which has improved to 81% with the implementation of the solid set system, increasing pasture production. Typical production levels for irrigation with low DU are 6-8 tonnes of dry matter per hectare per year (t DM/ha/year). With the improved uniformity, pasture production is expected to increase by 10-12 t DM/ha/year, to around 20 t DM/year for the 5ha irrigated, with a minimum estimated value of $5,000 (which has been included in the cost savings). These improvements haven’t been translated into increases in milk production.
From the implementation of recommendations in the audit, the farm has reduced total energy consumption by 1%, pump usage by 17%, and total costs by 37%, with Carbon emission savings of 0.4 t/CO2-e per year.
Table 3. Pre and post implementation energy consumption, costs and energy productivity improvements.
Metric | Pre-implementation | Post-implementation | Reduction (%) |
Energy Consumption (kWh) | 48,500 | 47,968 | 1 |
Cost ($) | 15,500 | 37 | |
Energy Productivity (kWh/unit) | 40.4 | 40 | 1 |
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.
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.