Energy Savers
Mackay

Mackay Cane Farm

Proposed
21
Proposed Energy Savings
Industry
Cane
Location
Mackay
Irrigation
Boom
Pumps
Centrifugal
Solution
Incorporate two irrigation booms on one efficient VSD and pump with part load covered by solar PV. Adopt management changes to increase production making use of the available water.

Farm Profile

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 currently irrigated by a 4” winch from two dam pumps could increase yields from the delivery of more water with irrigation changes recommended in the audit.

To save energy, the cane farm could improve efficiency onsite with the installation of;

  • Two Variable Speed Drives on both dam pumps with Dam Pump1 replaced by a 70L/sec pump to enable both irrigators to be operated from the same pump
  • A 30kW ground mount solar system providing offset against pump use while factoring in additional export when irrigation is not occurring
  • An immediate tariff change saving $1,635p.a. using both T20 and T33
Recommendation Cost to Implement ($) Energy Savings (kWh) Cost Savings ($) Payback (Years)
Purchase two booms upgrade river pump and install VSD 47,000 30,710 7,979 5.9

 

Install Ground Mount 30kW Solar PV 21,000 60,000 6,002 3.5

 

The total energy savings from the implementation of a new pump and VSDs, and the addition of a 30kW solar system is estimated to be $13,981 from current water use. Post recommended changes would result in tariff savings of $590.

The auditor’s report recommended changes to both electrical equipment and management practices to increase productivity, reduce energy consumption and costs onsite.

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 Savings as result of increased irrigation

Recommendation Cost to Implement ($) Energy Savings (kWh) Cost Savings ($) Increased Productivity Returns ($) Payback (Years)
Purchase two booms upgrade river pump and install VSD 47,000 14,179 2,690  

34,963

1.2

 

Install Ground Mount 30kW Solar PV 21,000 60,000 6,002 3.5

 

The total estimated cost of the improvements is $68,000 with the average payback period reduced from 4.7 of 1.6 years due to the productivity gains

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 great way for a business to cut costs and boost productivity. Find out about what’s involved in an energy audit 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.