Stock water is pumped to a header tank by a 3.7kW three-phase pump powered by a diesel generator for 12-14 hours each night. Although the generator does have a timer and input control, for ease of use, it is filled each night with 20L of diesel and run until it is out of fuel. The pump pushes approximately 2m3/hr and due to iron bacteria in the water, needs to be replaced approximately every 2-3 years.
The audit has made a comparison of the costs and savings of solar pumping which include the installation of a new Lorentz solar pump at a cost of $15,000 and either:
- Using the existing diesel generator for backup; or
- Removing the diesel generator and replacing with batteries.
Assuming the solar runs for eight hours per day with backup supplied for four hours
- Using Existing Generator:
- Reduce the current fuel use by 1/3rd to 2,435L saving $5,990.10 p.a. from the installation of the solar pump.
- Assumed generator maintenance cost of $950 p.a.
- Payback 2.16yrs, 46% ROI with cost savings of $5,990 p.a.
- Replace existing diesel generator with solar pump and battery backup:
- Requires an added cost of $12,500 to install battery back-up system.
- Cost saving amounts to all fuel and servicing of the generator $9,935 p.a.
- Payback 2.7yrs, 36% ROI.
||Add a Solar Pump and:
|Use Existing Generator
||Replace Generator with battery backup
|Annual Energy Saving (Litres Diesel)
|Estimated Cost to Implement
||Solar Pump: $15,000
||Solar Pump: $15,000
|Annual Cost Savings
|Carbon Emissions Reduction (t CO2-e)
This case study concentrated on the one irrigation system although the energy audit showed additional savings that could be made onsite including:
- Install Variable Speed Drive (VSD) on a 3-phase feed mill motor
- General Motor maintenance
- Installing a 17kW Solar System
- Install bore pump control
The audit showed on average the farm consumes over 55,000kWh p.a. at a cost of $16,900 p.a. This equates to a total energy cost per head of $4.30. If all recommendations are implemented the energy cost per head would be reduced to $0.86.
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