High capacity, reliable refrigeration systems are essential for provision of quality seafood, particularly from remote areas of the Northern Prawn Fishery (NPF). Recent policy changes by the DSEWPaC to pursue reduced greenhouse gas emission targets will result in phasing out of the most commonly used refrigerant, R22. The proposed shift towards use of natural refrigerants has highlighted a need to urgently consider alternative options suitable to fishing operations in the NPF, and review practice and system design changes that may be required.
Adaptation to natural refrigerants may be a viable option for land-based refrigeration systems, however the size, complexity, location and purpose of refrigeration systems used aboard NPF vessels are likely to prevent adaptation or modification of existing systems without significant safety, operational and/or cost implications which are impractical and unsustainable for NPF operators.
Significant seasonal/spatial variability in availability of target prawn species can radically influence refrigeration load requirements in the NPF. Consequently, NPF systems are uniquely designed with capacity to snap freeze 5 tons of 25°C product down to -18°C in 8–12 hours, with a holding capacity at -35°C of 30–40 tonnes. This freezing and storage capacity is uncommon among refrigeration systems, particularly among vessel-mounted systems. Consequently, alternative options are likely to significantly limit freezing capacity of NPF vessels, impacting on the economic value of Australia’s most valuable Commonwealth-managed fishery.
Additional factors including the significant distance between fishing grounds and ports, limited ability of vessel engineers to maintain complex refrigeration systems, and significant dangers associated with use of highly volatile refrigerant alternatives also necessitate use of safe, simple, reliable refrigeration systems, further limiting adaptive options able to be applied to NPF vessels.
There is an urgent need to review options able to be applied to NPF fishing systems and identify an uncomplicated, reliable, high capacity, compact and inexpensive solution.
Final report
Modern fishing fleets and the fish product supply chains are entirely dependent on effective and reliable refrigeration systems, from the point of catch to consumption.
The fishing vessels of the NPF (Northern Prawn Fishery) have one of the most demanding tasks for refrigeration equipment, operating in constrained spaces, under heavy load, in high ambient temperatures, requiring snap freezing of tonnes of sensitive product using equipment operating in a moving vessel, with heavy vibration and exposed to corrosive salt spray and water. Aside from the severe mechanical constraints and conditions, this demanding refrigeration task is only easily achieved using HCFC-22 (R22), a refrigerant that is on the verge of being completely phased out within a matter of years. HCFC-22 is rapidly becoming unaffordable, typically selling for $110 per kilogram with an average vessel requiring from 200 to 300 kilograms.
Further down the supply chain, the very large refrigeration system around which the SFM (Sydney Fish Market) is built, is also at the end of its design life and reliant on more than half a million dollars of the same refrigerant, HCFC-22. The SFM have few of the mechanical constraints and conditions of the NPF fleet, however it has other significant issues that have to be managed in design and replacement of the existing system. Aside from the logistics of replacing a working system of this size, in a facility that requires 7 days per week operation to maintain the stock in trade, the locality of the SFM, on the edge of the largest CBD in Australia, in the middle of an active tourism, retail and hospitality precinct, means that the use of certain refrigerants that have potential safety issues is unlikely to be acceptable, even though they may be the best technical solution to the requirements.
Recent policy changes by the Department of Sustainability, Environment, Water, Population and Communities (now Department of Environment) to pursue reduced greenhouse gas emission targets by imposing a carbon based levy on HFC refrigerants in conjunction with the phase out of HCFC refrigerants including the most commonly used refrigerant R22 under the Montreal Protocol leaves the NPF fleet with a technical, commercial and OHS dilemma. The proposed shift towards the use of low GWP refrigerant such as natural refrigerants has highlighted a need to urgently consider alternative options suitable to fishing operations in the NPF, and review practice and system design changes that may be required.
