Mackay Cane Farm
Energy Savings: 93% | Cost Savings: $6,000 | Capital Cost: $21,000 | CO2 Savings: 48.6 | Project Status: implemented
Industry:
Sugarcane
Location:
Mackay, Isaac and Whitsunday
Pump Type:
Centrifugal
Irrigation Type:
Boom
Technology:
Irrigation and Pumps, Solar Power and Renewables
A 144ha cane farm in the Mackay region producing 9500t of cane per year could see significant production and energy efficiency gains from findings in a recent Energy Audit.
The farm is currently irrigated by a 4” winch from two dam pumps and could increase yields from the delivery of more water through the implementation of irrigation adjustments as recommended in the audit.
A recent energy audit showed how improving the current systems can lead to energy and cost savings, improving efficiency onsite. The audit recommended to install:
- Two-Variable Speed Drives on both dam pumps, with the 130ML Dam Pump being replaced by a 70L/sec pump to enable both irrigators to be operated from the same pump.
- A 30kW ground-mounted solar system providing offset from the grid against Dam Pump energy use, while factoring in additional export when irrigation is not occurring.
- An immediate tariff change saving $1,635p.a. using both T20 and T33.
Table 1. Costs and savings from audit recommendations.
| Recommendations | Capital Cost ($) | Energy Savings (kWh) | Cost Savings ($) | Payback (Years) |
| Purchase two booms, upgrade pump and install VSD | 47,000 | 30,710 | 7,979 | 5.9 |
| Install 30kW Ground Mounted Solar PV system | 21,000 | 60,000 | 6,000 | 3.5 |
The auditor’s report recommended changes to both electrical equipment and management practices to increase productivity, reduce energy consumption and costs on site.
Over the past ten years, there has been a linear reduction in yield of 5t/ha. As a result of changes in rainfall distribution, a crop mix weighted towards older ratoons and the inability of the irrigation infrastructure not being able to meet crop demand at critical times. The farm typically produces above the zonal average, however.
By increasing water use from 159ML to 265ML with the use of two second-hand low-pressure booms and replanting old ratoons the farm could increase yields by 12 tonnes/ha based on productivity data from the 2019 season. An increased estimated net profit of $34,963 with energy savings of $8,692, even with the increased use of water. The pumping costs across all systems on average have been reduced from $117.73/ML to an estimated $37.89/ML.
Table 2. Savings as a result of increased irrigation.
| Recommendation | Capital Cost ($) | Energy Savings (kWh) | Cost Savings ($) | Increased Productivity Returns ($) | Payback (Years) |
| Purchase two booms upgrade pump and install VSD | 47,000 | 14,179 | 2,690 | 34,963 | 1.2 |
| Install 30kW Ground Mounted Solar PV system | 21,000 | 60,000 | 6,002 | 3.5 |
The farmer has proceeded with the installation of the solar pumping system. Actual savings will be updated once the measurement and verification process is complete.
By installing the recommendations in the audit, the business is expected to reduce energy consumption by 93% and costs by 32%, with carbon emission savings of 48.6 tCO2-e per year.
Table 2. Pre and post audit energy and costs savings
| Metric | Pre-Audit | Post-Audit | Reduction (%) |
| Energy Consumption (kWh) | 64,300 | 4,300 | 93 |
| Costs ($) | 18,700 | 12,700 | 32 |
Further, Capacitance probes were recommended to be installed to a depth of 90cm. This will provide invaluable data on the rooting depth, the amount of water the crop requires and any impediments or compaction layers and possible changes of the soil characteristics. This has the potential to further improve water use efficiency.
An energy audit is a good investment
An energy audit is a great way for a business to cut costs and boost productivity.
The Energy Savers Plus Extension Program was delivered by the Queensland Farmers' Federation with support and funding from the Queensland Department of Energy and Public Works.
