Atherton Tablelands Grains and Fodder Farm
Energy Savings: 49% | Cost Savings: $7,455 | Capital Cost: $30,000 | Project Status: Implemented
Industry:
Grains and fodder
Location:
Atherton Tablelands
Pump Type:
Centrifugal
Irrigation Type:
Centre Pivot
Technology:
Irrigation and Pumps, Solar Power and Renewables, Variable Speed Drives
An Atherton Tablelands cropping business has reduced the amount of electricity it purchases for irrigation after implementing solar PV and variable speed control on its irrigation pumping system.
The farm produces around 7,000t of hay over 41 hectares, with most of the energy used for irrigation. The annual energy consumption for the site during the 2018-2019 period was 63,642kWh at a cost of $14,052.
The farm operates a centre pivot which is supplied with water from an irrigation scheme.
The project demonstrates the value of following an energy audit through implementation and then using measurement and verification (M&V) to understand how the new system is actually performing.
The audit
The energy audit identified several opportunities to reduce energy consumption and cut costs, including:
- Installing a 40kW solar system with a 30kW inverter to cover baseload power with possible export.
- Installing an automated control system with an SMS alert in the pump station, with a capital cost of $3,500.
- A change in strategy to day-time pumping using energy produced from solar onsite, with a shift to Tariff 20 from an expiring agricultural tariff.
| Recommendation | 40kW Solar PV |
| System Cost | 40,000 |
| Energy Savings T62 (kWh) | 3,999 |
| Energy Savings T20 (kWh) | 46,656 |
| Cost Savings T62 ($) | 1,851 |
| Cost Savings T20 ($) | 12,539 |
| Payback period T62 (Years) | 21 |
| Payback Period T20 (Years) | 3.2 |
| Emission Savings T62 (tCO2-e) | 3.2 |
| Emission Savings T20 (tCO2-e) | 37.3 |
Measuring the result
Measurement and verification compared electricity purchased from the grid with the volume of water pumped before and after implementation.
| Measure | Before | After | Result |
| Water pumped | 386 ML | 240 ML | Different reporting volumes |
| Grid electricity purchased | 72,966 kWh | 23,007 kWh | Different reporting periods |
| Purchased electricity per ML | 189 kWh/ML | 96 kWh/ML | 49% reduction |
| Electricity cost per ML | $41/ML | $21/ML | ~$20/ML saving |
Because the baseline and reporting periods involved different volumes of irrigation, kWh per megalitre is the most useful comparison. M&V found that purchased electricity per megalitre fell by 49%, while electricity cost associated with pumping fell from approximately $41 to $21 per megalitre.
This represented a 49% reduction in purchased electricity per megalitre pumped.
During the M&V reporting period this represented $4,849 in reduced electricity purchases. Solar exports generated a further $2,506, giving a total calculated reporting-period benefit of $7,355.
M&V identified the next opportunity
The M&V process did not finish with confirming the savings. It found that 31,878 kWh of solar electricity was exported to the grid during the reporting period, which is more than the site purchased from the grid for irrigation.
An opportunity identified was to review irrigation operating times and, where practical, increasing daytime irrigation so more solar electricity could be used onsite to increase the savings
It also recommended improved metering to support ongoing monitoring of electricity consumption and solar performance.
The next step
This case study shows how M&V is more than a check-up on the audit and implementation and that predicted savings were achieved. Verification confirmed a substantial reduction in purchased electricity per megalitre, while also identifying an opportunity to capture more value from the investment.
The energy audit identified the opportunity. The farmer invested in the upgrades based on the audit recommendation. M&V demonstrated that the project had achieved savings and highlighted what the farm could do next.