A recent energy audit showed how improving the current systems can lead to energy and cost savings. The recommendations explored in the audit and implemented included replacing the dam pump with an 11kW unit and installing a 9.75kW solar PV system, which have achieved energy savings of 231% per year. Additionally, a switchable real-time energy meter has been installed on the pump circuit allowing monitoring of energy consumption and control of the pump from a mobile device.
Energy Savers
Summary
The farm, near Stanthorpe, produces wine grapes and has a cellar door. It is irrigated for 9 months of the year, depending on rainfall. Water is supplied from an onsite irrigation dam and is replenished by rainfall.
It is a small site consuming 7,500 kWh per year during the period 2018-2019, at a cost of $2,500. The farm usually produces enough grapes for 12,000 bottles per year, but the droughts have significantly reduced this. Their current energy benchmarking is 1kWh per bottle of wine.
The infrastructure contributing to the energy consumption onsite consists of:
- A very old dam pump of unknown size, which is the main consumer of electricity.
- A cellar door and showroom.
- Other tools such as farm machinery and anti-frost fans.
A recent energy audit showed how improving the current systems can lead to energy and cost savings. The energy audit recommended the following changes to improve efficiency and reduce costs:
- Tariff analysis, which found that the farm was on the correct tariffs.
- Replacing the dam pump with an 11kW unit, allowing for vineyard expansion since it can irrigate larger areas, and reducing the farmers’ time in changing paddocks over. Also, the new pump will improve the efficiency of the irrigation system.
- Installing a 9.75kW Solar PV system with an 8.2kW inverter onto the cellar door roof to offset most of the energy consumption on that meter. The solar system also allows for future growth of the vineyard and more electricity use in normal non-drought conditions, and even export power to the grid.
Table 1. Energy and cost savings from audit recommendations
| Recommendations | Annual Energy Savings (kWh) | Annual Cost Savings ($) | Emission Savings (tCO2-e) | Capital Cost ($) | Payback Period (years) |
| Pump replacement | 1,000 | 360 | 0.8 | 8,000 | 22 |
| 10.75kW Solar System | 15,000 | 2,100 | 12 | 11,500 | 5.4 |
| Total | 16,000 | 2,460 | 12.8 | 19,500 | 8.9 |
The pump replacement had a large payback period since it was calculated based on low consumption recorded during the drought, however, the farmer was optimistic that the payback would be shorter.
Following the audit report recommendations, the grower proceeded with the installation of the new pump and a 10.4kW solar system with an 8.2kW inverter connected to the pump NMI instead of the cellar door. The savings made have been measured in a Measurement and Verification (M&V) process, as outlined in Table 2.
Table 2. Estimated and Actual annual energy and cost savings.
| Metric | Audit estimation | M&V calculation* | Variation (%) |
| Energy Savings including exports (kWh) | 16,000 | 17,300 | 8 |
| Cost Savings including exports revenue ($) | 2,460 | 2,050 | -17 |
*Extrapolated from 4 months of measured data, considering the seasonality of solar generation according to audit calculations.
Compared to those estimated in the audit, the lower cost savings achieved have been influenced by changes in solar energy use. Around 3,450 kWh – 21% of total solar energy generated – are being used onsite valued at $815, and about 12,850 kWh are being exported to the grid with a revenue of $1,010. Considering that energy is being imported from the grid, there are potential savings from shifting consumption into the solar generation period.
The next step for the farm is to adjust energy usage to offset as much energy consumption as possible from the grid, which would lead to further cost savings since the revenue from feeding into the grid is lower than the cost savings from using the energy onsite.
Additionally, a switchable real-time energy meter has been installed on the pump circuit allowing monitoring of energy consumption. During times of excess solar generation, the site can decide to pump, should the crop require. The grower will be able to turn the pump on from a mobile device at any location provided they have mobile service. Also, a real-time energy meter will allow the business to understand their energy consumption and find further demand reductions onsite. Read more about that HERE.
By installing the recommendations in the audit, the business has reduced energy consumption by 231%, thus becoming a net exporter of power. Costs have been reduced by 92%, with Carbon emission savings of 14 tCO2-e per year.
Table 2. Pre and post implementation energy and cost improvements.
| Metric | Pre-Implementation | Post-Implementation | Reduction (%) |
| Energy Consumption (kWh) | 7,500 | -9,800 | 231 |
| Cost ($) | 2,230 | 180 | 92 |
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 onsite.
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.
