A 400–acre mixed enterprise consisting of a piggery producing sweet corn, green beans and broccoli could benefit from a recent energy savers audit. The piggery has 2.2 cycles per year finishing on average 2600 pigs per annum.
The total energy consumption onsite is distributed through two meters. One is considered a Large Asset Customer (LAC), while the other is a Small Asset Customer (SAC). The site has access to contestable tariffs and is currently operating on optimal tariff 8300. The first meter recorded 302,135 kWh with a maximum demand of 100 KVA at a cost of $54,523 per annum. The second used 15,117 kWh with $4,664 in costs. The total energy consumption onsite is 317,252 kWh, costing $59,187 per annum.
Irrigation of the two cropping paddocks is associated with two meters, one on the larger account, and the other smaller account. This case study focuses on the irrigation systems following recommendations explored in the audit:
- Two low-pressure irrigation options, one with a new boom and one without it.
- A standalone 189kW solar PV system with a 500kWh battery bank as a backup.
Table 1. Recommendations in the audit and associated energy and cost savings.
|Capital Cost ($)
||Energy Savings (kWh)
||Cost Savings ($)
||Payback Period (Years)
|Low-pressure irrigation without Boom (Meter 1)
|Low-pressure irrigation with Boom (Meter 1)
|Low-pressure irrigation without Boom (Meter 2)
|Low-pressure irrigation with Boom (Meter 2)
|189kW solar PV and 500kWh battery system
On the large account, a submergible pump moves approximately 62 ML of water from the creek to the dam per annum. It is then used for supplying drinking water to the piggery and an irrigation system. For the piggery, water is treated and pumped to the piggery holding tanks, which operate on a low limit float switch. For irrigation, a manually operated pump with a 37kW motor delivers water through a 150mm diameter pipe to irrigate the lower paddock through a travelling gun.
The upper paddock, attached to the smaller account, uses a similar system, a 37kW motor and pump with a measured absorbed power of 24.6 kW deliver water from the dam to the irrigator through 150mm piping. The annual water consumption calculated based on account energy and pump performance is roughly 33.5ML per annum. Irrigation for both paddocks is completed during daylight hours and manually operated based on farming experience and crop type.
The audit recommended to downsize and install a new 16kW pump with 150mm header and piping connections, a non-return check valve on both pumps and irrigating through a new low–pressure boom. The irrigation recommendations in the audit compared the savings for both meters, with and without a new boom. Due to the increase in dollar savings and the quicker payback it is recommended to install the new system without the boom on the SAC account that supplies the upper paddock. It was noted that replacing the travelling gun with a boom may provide a production benefit. Further investigation into automation may show additional efficiencies for the site, with improvements in production and an increase in profit.
Should the site install the above solar and battery recommendations with energy savings in the order of 99% and operating cost saving of 96%. The small irrigation (upper crop) account would reduce by approximately 36% or $1,504 +GST under the current tariff. However, as the payback for the battery system is 18 years it is not recommended to install. Should battery costs decrease, the paybacks may reduce and bring the payback period within warranty periods and the expected life expectancy of infrastructure. Under this non-traditional approach, the site could become energy neutral and the tariff would change to a small business user T-7100 for backup power only.
The recommended solution is the replacement of a low-pressure irrigation system without boom, which includes an implementation cost of $10,000 and allows the farm to reduce 2% of its total energy consumption, with carbon savings of 4.4 t CO2-e per year.
Energy Audits for your Business
An energy audit is a great way for a business to cut costs and boost productivity.
An energy auditor will review your past energy bills, your equipment and the way your business operates. They’ll show you where you’re using excess energy and explain what you can do about it. Find out about what’s involved in an energy audit HERE.
See our range of agricultural energy efficiency case studies 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 email@example.com.
The Energy Savers Plus Extension Program is delivered by the Queensland Farmers Federation with support and funding from the Queensland Department of Energy and Public Works.