Energy Savers
Mareeba

Mareeba Irrigation Farm

Proposed
89
Proposed Energy Savings
Industry
Irrigators
Location
Mareeba
Pumps
Centrifugal
Irrigation
Centre Pivot
Solution
Solar PV, Pumping, Tariff, Management Changes.

Farm Profile

The farm produces around 7,000 tonnes of hay per annum with an irrigation system consisting of one centrifugal pump pumping water from a reticulation system to a centre pivot. Most of the electricity consumption on site is due to pumping. The total energy use onsite for the pump including the house is over 55,500kWh at a cost of over $14,000 per annum. The farm is currently using the obsolete Tariff 62, pumping at night during off peak times.

The energy audit identified several opportunities to reduce energy consumption and cut costs including:

  • Installing a smaller more efficient pump.
  • Installing a 40kW solar system with a 30kW inverter to cover base load power with possible export.
  • A change in strategy to day-time pumping using energy produced from solar on-site, with a change to Tariff 20.

The Farmer has already implemented the Solar PV system and the case study will be updated with actual savings once data is available.

Recommendation  Energy Savings T62 (kWh)  Energy Savings T20 (kWh) 

 

Cost Savings T62 ($)  Cost Savings T20 ($)  Payback period T62 (Years)  Payback Period T20 (Years) 
40kW Solar System  3,999  46,656  1,851  12,539  21  3.2 

 

After talks between the auditor, electrician and the farmer, the best efficiency and production outcomes for the site were determined. The solar system has been designed to cover the load expected by the pump with any allowable export to the grid.

The 39.6 kW Solar array with 30kW inverter capacity has been arranged in an East – West configuration. As the irrigators run for long periods, the panels facing East will get to maximum capacity earlier in the morning with the panels facing West producing maximum power in the afternoon providing constant supply through the day.

As the invertor capacity is no larger than 30kW the system was treated as a micro embedded generating unit keeping the connection process simple and meaning the farm is still able to export during times of no irrigation. Maintaining grid connection allows the irrigator to draw grid power when required.

The auditor recommended the farm move to a flat rate Tariff 20 and shift pumping to daylight hours while the solar PV System is producing enough energy. Implementation of solar PV will absorb the increased tariff rate and any potential price increases in the future reducing the overall costs by 89%.

Recommendation  System Cost  Energy Savings T62 (kWh)  Energy Savings T20 (kWh) 

 

Cost Savings T62 ($)  Cost Savings T20 ($)  Payback period T62 (Years)  Payback Period T20 (Years) 
40kW Solar System with 30kW inverter  40,000      3,999  46,656  1,851  12,539  21  3.2 

 

Further, ‘time’ efficiency measures have been achieved using automation on the centre pivot. With the main farmhouse around 10 minutes from the irrigator, regular drives are required to start and stop its operation. The automation will reduce fuel usage and allow time to be better spent on the crop. Should the centre pivot stop working, a SMS is sent to a mobile device alerting the operator.

The farm produces around 7,000t of hay over 41 hectares. Pumping accounted for 95% of the total energy use. With estimated energy savings from the grid of 46,656kWh a energy grid energy consumption (kWh) per tonne of hay will be significantly less.

Audit Stage  Grid Energy Use (kWh)  Cost ($)  Grid kWh/t of Hay Produced 
Pre-Audit  52,753  13,349  7.5 
Post-Audit  6,097  N/A  0.87 

 

The accuracy of the recommendations in the audit coupled with the specialist electrician’s advice provided the best possible outcome for the farm. 

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.