INTEGRATION OF ENERGY AUDITS INTO LIFE CYCLE ASSESSMENT METHODOLOGY TO IMPROVE ENVIRONMENTAL PERFORMANCE OF RECIRCULATING AQUACULTURE SYSTEMS

In Recirculating Aquaculture Systems (RAS), water is continuously treated and recirculated as opposed to being discharged untreated into the environment as in other types of fish production systems; the design and production parameters will determine the overall energy consumption. This energy-intensive nature hampers their sustainability and cost-effectiveness. A combination of two methods (i.e. Life Cycle Assessment (LCA) with energy audits) to: improve environmental performance of RAS, identify energy consumption and thus, its environmental and monetary effects in order to seek cost reduction is proposed. Likewise, an online software analyzing system's consumption patterns (principal and partial consumptions); anomaly detection and correction of habits; identification of opportunities for improvement; and assessment of potential economic progress. The methodology was proved with a case study focused in a pilot-scale RAS unit used in codfish (Gadus morhua) production, located in the Basque coastal area (northern Spain). Feed and juvenile production/transportation, oxygen transportation and energy consumed during the whole experiment were considered as inputs for the assessment. Energy consumption was measured both continuously by an energy meter embedded in the RAS unit as well as with a portable energy analyzer to measure each of the energy-consuming devices independently. Main consumers included the heat pump, followed by the main and secondary pumps, respectively. Energy audit's results show the success in identifying the devices that consumed the largest amount of energy, and recorded data served to feed the Life Cycle Inventory and perform a more complete and precise LCA. Fossil fuel based on-farm electricity for the on-growing of fish was shown to be the most environmentally unfriendly input; it was the major impact producer in the assessed impact categories. It showed a temporal variability depending on the water temperature, which was the main factor linked to the energy use. The combination of LCA and on-farm energy audit presents a useful tool to conduct a more complete assessment with results that can be used to design a less energy intensive, profitable and sustainable system.