Modelling thermal environment of a recirculating aquaculture facility

Economic viability of fish production in a recirculating aquaculture system (RAS) facility depends, in part, on minimizing the energy requirements of operating such facilities. A step-wise, steady-state thermal model was developed to simulate the RAS thermal environment and energy expenditure for heating, ventilation, water pumping, biofilter operation, and lighting over a production cycle. The model was validated using temperature and energy data collected from the RAS facility of Virginia Tech during 1992. Simulations were performed with various production scenarios. Heating makeup water and the building required the most energy (40-70% of total), followed by water pumping, biofilter operation, lighting, and ventilation. The heating energy requirement of the facility increased with an increase in either fish stocking density or wastewater discharge from the facility due to increased heat loss through water replacement. However, the energy cost of production ($/kg) was the lowest for high stocking- density production scenario. Heat recovery from discharged wastewater is recommended to reduce the energy cost of fish production in RAS.