New Zealand has the perfect setting for a thriving aquaculture industry which includes Moana New Zealand, NZ's largest Māori owned fisheries company. Moana has developed a pāua farm supplied with some of the highest quality ocean seawater in the world through a natural deep-water intake. The farm is located within NIWA's Bream Bay Aquaculture Park and has the capacity to produce over two million pāua (120 tonne) annually.

The Requirements

The pāua (internationally known as blue abalone) are worth up to $100 USD per kilo, making the farm a precious asset for Moana to invest in and the pāua important to protect. In summer of 2016 a heat wave caused the pāua to suffer from higher water temperatures. Ideal seawater temperatures for pāua are 17.5-18°C. They can tolerate colder temperatures, but become stressed in temperatures of 20°C or higher.

Asset Manager for Moana New Zealand, Paul Beardsell, wanted to safeguard their breeding stock from uncomfortable temperature changes and looked for solutions to control the temperature of the seawater used in the farm. Previous experience and recommendations from NIWA lead him to contact Hot Water Heat Pumps Ltd.

The Solution

Hot Water Heat Pumps Ltd tailored a solution using a variable capacity Performance Plus 7GP65HC-3 heat and chill unit with some special features built in to meet Moana's needs.

The heat and chill unit needed to get the new seawater being continually introduced from the ocean to the correct temperature before it enters the pāua tanks because any fluctuations in temperature would have an immediate effect. A Copeland Scroll Digital Compressor was used to provide variable capacity on the unit and cater to the tight outlet temperature control required. This feature also increases system efficiency providing greater energy savings.

The latest controller technology was installed to provide advanced control and allow remote monitoring to be added to the unit. A transceiver was fitted to the unit connecting it to the New Zealand wide 'Internet of Things' (IoT). The network is made available by ThinXtra utilising Sigfox technology — an ultra-low power, low cost, long range network that is particularly good for transmitting small amounts of information. Performance of the heat and chill unit could then be checked and targeted maintenance can be conducted before breakdowns occur, reducing potential downtime that could otherwise cause temperature fluctuations.

The Result

Moana is happy with the solution. They continue to fine tune the system with the help of Hot Water Heat Pumps Ltd and the information provided by remote monitoring. Joss Birss, Pāua expert at Moana New Zealand commented, "Since the Performance Plus heat and chill unit was installed, we have not lost any of our breeding stock, and we are seeing increased rates of growth which will only increase productivity."