Two Western Downs cotton farms and a Mareeba cane farm have shown that irrigation energy efficiency has more benefits than just the power bill savings. Following detailed pump energy audits as part of the Energy Savers Plus Program, all three farms have implemented projects that are saving on power bills.
One of the cotton farms, located in Cecil Plains, was able to increase their water flow rate by over one third with a smaller pump, improving energy efficiency by 43%. And while the energy audit estimated a payback period of almost ten years based on electricity bill savings, the farmer saw an opportunity to reduce maintenance costs by switching from a 30kW line shaft pump to a 15kW submersible and increased the daily pumping capacity from 2.1 to 3.7 megalitres/day. These changes have reduced the farm’s annual electricity costs by over $2,600.
Following an energy audit, a Brookstead cotton farm removed two stages from a seven-stage 30kW pump, reducing the flow rate but improving the combined energy efficiency by 25%. The electrical demand has been reduced by 12kW and even with increased running time, running costs have reduced by $1,200 per year with a payback period under two years.
In these cases, the amount of energy required to pump each mega litre of water up one metre of head (kWh/ML/m) was reduced significantly. In both examples, the audits had estimated the costs of installing solar power systems of 25kW and 45kW respectively. However, the farmers decided not to implement these recommendations at this time as the low number of pumping days means they would not be used enough to offer a suitable payback period.
The final case study of a Mareeba cane farm tested a number of pumping scenarios to find the best efficiency point and the best operating conditions for overall system productivity. The audit recommended optimising the speed of the centrifugal pump, direct-coupled to a high efficiency 160kW motor with a Variable Speed Drive. This no-cost project to reduce friction losses is saving the farmer nearly $20,000 per annum with a reduction of 19% energy consumption.