A Southern Downs nursery has saved money and reduced energy consumption after implementing the recommendations from a recent Energy Savers Audit. The farm implemented the recommended refrigeration upgrades.
A Southern Downs nursery has saved money and reduced energy consumption after implementing the recommendations from a recent Energy Savers Audit. The farm implemented the recommended refrigeration upgrades.
The farm has two peak packing blocks, February to April and June to August, with the highest energy consumption, producing around 100,000 units per year.
The annual energy consumption for the site during the 2018-2019 period was 427,300 kWh at a cost of $127,540, with a 100kW solar PV system already implemented on the roof of the packing shed and two small 5kW systems connected to the irrigation pumps.
As the shed operates seasonally, there are six months of low usage in September–January and May, with shutdowns of packing operations. In this period, the inverter of the installed solar system is periodically switched off due to export restrictions by Ergon, given the size of the system and its operating voltage. This management practice reduces the performance of the system and the potential income from the energy generated, which is expected to change with the new regulations of the retailer to be able to export the remaining power to the grid.
The energy consumption on the farm consists mainly of:
A recent energy audit showed how improving the current systems can lead to energy and cost savings. The audit recommendations are:
Table 1. Costs and savings from audit recommendations.
Recommendation | Annual Energy Savings (kWh) | Annual Costs Savings* ($) | Emission Savings
(tCO2-e) |
Capital Cost ($) | Payback Period (Years) |
Change of tariff | 0 | 12,094 | 0 | 0 | 0 |
Smart metering | 8,600 | 4,221 | 7.0 | 11,000 | 2.6 |
Maintenance of solar PV | 9,264 | 4,000 | 7.4 | 5,000 | 1.3 |
VSD on fan motors | 17,951 | 7,767 | 14.4 | 18,000 | 2.3 |
Pressure reduction | 400 | 173 | 0.3 | 0 | 0 |
Strip curtains | 6,000 | 2,596 | 4.8 | 6,000 | 2.3 |
Total | 42,215 | 30,851 | 33.9 | 40,000 | 1.4 |
*Calculated considering current tariff 62.
The farmer installed VSD on cold room fan motors and a smart metering device in the main switchboard. The savings made with the VSD solution have been measured in a Measurement and Verification (M&V) process, as outlined in Table 2.
Table 2. Estimated and Actual energy and cost savings.
Metric | Audit estimation | M&V calculation | Variation (%) |
Energy Savings (kWh) | 17,951 | 10,448 | -42 |
Cost Savings ($) | 7,767 | 3,448 | -55 |
The lower energy and cost savings obtained from the M&V calculations compared to those estimated in the audit have been influenced by the lower total run hours of the cold room fans during the measured period, having used the fans at full capacity only 53% of the time considered for the estimation of the savings in the audit.
From implementing the recommendation in the audit, the farm has reduced total energy consumption by 2%, costs by 3%, and Carbon emission savings of 8.5 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) | 427,300 | 416,852 | 2 |
Cost ($) | 127,540 | 124,092 | 3 |
Energy Productivity (kWh/unit) | 4.3 | 4.1 | 2 |
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.