An energy audit for the on-site electricity usage recommended the installation of variable speed controls on pumps, replacement pumps with more energy efficient drive units, hot water system replacement, lighting replacement, air conditioning upgrade options & installation of solar photovoltaic system.
The audit recommended replacing high pressure travelling guns with a low pressure boom irrigator and installing a variable speed drive to maintain 65psi at the booms. The project is expected to save 20% energy and has a payback period of 3 years.
The audit presented 2 options to improve the efficiency of an 18kW pump: upgrading to a high efficiency model, or adding an VSD, both of which would save nearly $4,000 per year and pay back within around 2 years.
The audit identified several energy efficiency opportunities including regular checks for leaks in the irrigation and compressed air systems and a lighting upgrade. The audit recommended a 10kW Solar PV system to complement energy efficiency practices already in place, to further cut power required from the grid by 35% to save over $4,000 per year with a payback of less than 5 years.
The audit recommended regular checking of cold room door seals to save up to 10% in refrigeration costs, along with incorporating 30kW Solar PV into a new shed being built at the site to offset pumping and refrigeration power consumption with a payback period of 4 years. Variable Speed Controls were recommended for 2 smaller pumps with a payback period of 7.7 years.
An audit recommended reducing the pump size from 45kW to 18kW to reduce water flow rate and friction head losses along with a variable speed drive due to the varying height of irrigation blocks. The farm will reduce pumping costs by nearly $3,200 per year with a payback of just over 4 years. A 15kW solar PV system will save an additional $6,000 per year with a payback of just over 3 years.
The case study provides an estimate of the costs and benefits of replacing a 36hp diesel irrigation pump two options: a mains connected 15kW pump or a 19kW pump powered by a 20kW solar array to get paybacks of 11 or 6 years respectively. The case study also compares the cost for a new pump of a 7.5kW mains connected pump and a 9.5kW pump powered by a 10kW solar array, to find a payback period of less than 1 year. The farmer would save over $77,000 on pumping costs over 10 years by installing solar pumping in both applications.
An audit of a Mundubbera Citrus farm recommended fitting variable speed drives to pumps, and a 30kW solar PV system. The farmer has implemented the findings, reducing the pump size as well, and adding over 80kW of Solar PV to save over $41,000 per year in electricity costs.