A 404 ha Southern Downs horticulture farm producing various vegetables has saved money and reduced energy consumption after implementing recommendations from a recent Energy Savers Audit.
Energy Savers
Summary
The farm irrigates year-round, producing approximately 1.6 units per ha per year.
The annual energy consumption for the site in the 2 NMIs audited during the 2018-2019 period was 17,888kWh at a cost of $2,723, and energy consumption on the farm consists of:
- Irrigation: 3 bore pumps and 3 centrifugal pumps connected in parallel.
- Refrigeration: 2 cold rooms used from November to May, one to reduce the temperature of the products and the other one to keep them at a constant low temperature.
- Hot water system.
Additionally, the farm has two 5kW solar systems installed on the pump shed and the cold room.
A recent energy audit showed how improving the current systems can lead to energy and cost savings. The audit recommendations are:
- Tariff Change: change from transitional irrigation tariff 66 that will be phased out in July 2021, to optimal Time of Use tariff 20, on a small user NMI.
- Replacement of one cold room condensing unit: replacement for a more efficient system with Variable Speed Drive (VSD) given the old age of the unit and the existing corrosion in it.
- New centrifugal pumps with VSD: replace the pumps with new units including VSD, to improve the efficiency of the irrigation system given the different pressure requirements of the irrigated fields.
- A 6kW Ground Mounted Solar PV: to offset the diesel consumption on farm used for a generator servicing a bore pump.
Table 1. Costs and savings from audit recommendations.
| Recommendations | Annual Energy Savings (kWh) | Annual Costs Savings ($) | Emission Savings
(tCO2-e) |
Capital Cost ($) | Payback Period (Years) |
| Tariff change | – | 2,320 | – | – | – |
| Condensing unit replacement | 1,230 | 300 | 1 | 20,000 | 66.6 |
| Pumps upgrade with VSD | 580 | 112 | 0.5 | 18,000 | 160.4 |
| 6kW Solar PV | 11,991* | 1,789 | 3 | 10,000 | 5.6 |
| Total | 13,801 | 4,521 | 4.5 | 48,000 | 48.9 |
* Diesel savings converted to electricity.
The grower has implemented a 3kW end-suction three-phase centrifugal pump to replace the 2 single-phase centrifugal pumps. The new pump has been connected to the main switchboard, on a NMI that was not audited.
The savings made have been measured in a Measurement and Verification (M&V) process, as outlined in Table 2.
Table 2. Estimated and Actual energy and cost improvements.
| Metric | Audit estimation | M&V calculation | Variation (%) |
| Energy Savings (kWh) | 580 | 2,592 | 447 |
| Cost Savings ($) | 112 | 603 | 538 |
The greater savings measured compared to those estimated from the audit recommendation have been influenced by installing one large pump instead of two small ones, and mostly by an increase in irrigation activity since during the audit the pumps were not working due to drought conditions.
From the implementation of recommendations in the audit, the farm has reduced energy consumption by 12% and costs by 17%, with Carbon emission savings of 2.1 t/CO2-e per year.
Table 3. Pre and post implementation energy and costs improvements.
| Metric | Pre-implementation | Post-implementation | Reduction (%) |
| Energy Consumption (kWh) | 21,633 | 19,041 | 12 |
| Cost ($) | 3,594 | 2,991 | 17 |
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.
