In this Queensland Farmers Federation case study, Gold Coast Tiger Prawns (GCTP), one of Australia’s largest black tiger prawn farming operations, installed variable speed drives and power factor correction equipment to achieve a 19 per cent saving in energy.


GCTP is based in rural Woongoolba in the northern Gold Coast region and has an annual production capacity of around 1,000 tonnes.

Electricity use is dominated by a large number of motors ranging in size from 0.37kW up to 55kW. These motors drive pumps for transferring water, paddle wheels to aerate the ponds, and conveyor belts in the processing and sorting factory.

In 2015, GCTP discovered that network electricity tariffs were going to change to include a kVA demand charge. This demand charge would increase the cost of electricity for the operation. In response, GCTP engaged Energy Correction

Options to review its electricity costs.

Two areas were identified with potential for savings:

  • The installation of variable speed drive (VSD) motors
  • The installation of power factor correction (PFC) equipment

Investigations revealed the power factor (PF) across various electricity grid connection points at maximum demand was dropping to near 0.8. The general requirement is for the PF to be 0.9 or better.

Capacitor banks totalling 775kVAr were installed at seven locations where high voltage power was distributed and stepped down for use across the property. The PFC panels were fitted with visible external alarms to alert farm operators if the units tripped and went into bypass mode so a service call could be arranged.

GCTP also upgraded a number of motors with VSDs, focusing on the motors with variable flow requirements. The largest VSDs were installed on the 55kW harvesting pumps which extract water and prawns from ponds for processing.

The VSDs allowed the pumps to maintain a constant water level in the collection drains without the need for stopping and starting which causes wear and tear on motors. PF was improved at maximum demand to up to 0.98.

This resulted in a reduction of up to 340kVA or approximately 20 per cent of total kVA, and delivered electricity cost savings of up to $3,400 per month in demand charges. A number of much smaller VSDs were also installed in motors attached to conveyor belts in the processing plant. These motors ranged in size from 0.37kW up to 1.5kW.

The VSDs allowed the belt speed to be adjusted during sorting and inspection according to the volume of prawns being processed at the time. The slow startup experienced with VSDs also reduced belt strain. By upgrading their motors with VSDs, GCTP improved the performance of their operation, reduced wear and tear on their equipment, and delivered electricity cost savings.

GCTP recognised the energy savings and financial benefits made possible by switching to variable speed pumps and installing PFC equipment, and made the decision to implement energy-efficient systems.

This case study was originally published by Queensland Farmers Federation.
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