Swire Cold Storage is part of the global Swire Group (which includes Cathay Pacific and Swire Pacific) and is, together with its sister company United States Cold Storage, one of the largest cold storage operators in the world. The Swire Group has been in Australia since the early 19th century operating in the fields of specialisedtransport, agricultural farming and shipping
Minus40 carried out an energy audit at Swire’s Cold Storage’s Lurnea Warehouse, evaluating several energy savings opportunities at the refrigeration plant. The audit was subsidised by the NSW Office of Environment and Heritage through its Energy Saver Program. OEH contributed 70% of the audit’s total cost.
Opportunities for improvement
One of the opportunities investigated by Minus40 was automated compressor staging and speed capacity control of the large rotary screw compressors.
Unloaded operation by slide valve modulated screw compressors is one of the large causes of inefficiency at industrial refrigeration plants. At the Swire Cold Storage site in Lurnea, it was observed that the compressors would frequently run unloaded throughout the cooler months of the year, resulting in significant inefficiencies.
By installing variable speed drives and correctly programming the compressor staging and capacity control logic to avoid compressor unloading via slide valve control, significant improvement in system efficiency can be expected. The energy audit highlighted the opportunity for sensible capital investment and the project was implemented.
As well as carrying out the initial energy audit, Minus40 was engaged to verify the savings from the project, a necessary step in order to apply for Energy Saving Certificates (ESC’s). It was shown that the electricity consumption was reduced by 786 MWh per annum. Subsequent application for ESC’s allowed recapturing some of the initial project capital investment.