The site energy consumption consists of:
- A number of large pumps that serve different areas of the farm. Some pump direct from the river and some from the irrigation dam.
- A large pump that pumps from the river to an irrigation dam which also irrigates some plots, responsible for approximately 30% of site energy use and is the highest user of energy
- A booster pump that pumped from the irrigation dam to the plots that could not be reached by the other pump, so double pumping occurred. This pump is approximately 3% of the site use and was chosen to be analysed to try and reduce the double pumping and some demand charges
- A packing shed
An audit of site energy consumption evaluated:
- Tariff analysis
- Installation of a solar PV system
- Upgrading the booster pump
- Installing smart water metering for irrigation scheduling
Of the energy saving opportunities evaluated, three initiatives were identified with potential energy saving of 7% of the site total, and approximately $90,000 p.a. with an average payback period of 5.5 years.
A tariff analysis was completed on the sites tariffs and it was found that there were savings of approximately $11,000 per year by changing the tariff on the largest pump. The pump was on Tariff 66, which is an irrigation tariff being phased out in July 2021. It was recommended to change to Tariff 50 which is a large Time of Use tariff.
The audit report recommendations included installing a new booster pump. A new booster pump would partially remove the need for the double pumping from the dam. A variety of duty points were tested and it was determined that a new, smaller pump (160kW to 75kW) would have returned a payback period of just over four years. A Variable Speed Drive (VSD) was also recommended to better control the pump flow rates and pump performance.
Other recommendations included installing a ground mounted solar system at the site of the large pump of 39kW, which resulted in a payback period of approximately 6 years. Changing the irrigation scheduling to match the solar output allowed for higher utilisation of the energy generated. Smart water meters were also recommended to better monitor volumes of water being double pumped and irrigation amounts.
Following the audit report recommendations, the grower proceeded with installation of the new booster pump, changing their tariffs and will install the solar in the future. Post implementation benchmarking is predicted at 223kWh/tonne of fruit produced. Measurement and verification is to be completed on the pump system in the coming months.
Estimated results of energy conservation measures are summarised below:
||New Booster Pump
||39kW Solar Installation
|Est. Cost to implement
|Est. Energy Savings
|Est. Operating cost saving
An energy audit is a good investment
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The Energy Savers Plus Extension Program is delivered in by the Queensland Farmers Federation with support and funding from the Queensland Department of Energy and Public Works.