Process Modeling and Life Cycle Assessment of a Large Pilot-Scale Aquaponics Facility at Auburn University

Abstract

Aquaponics has often been hailed as a more sustainable approach to fish and crop production when compared to traditional aquaculture and hydroponics. However, there have been insufficient data to support claim in addition to a general lack of studies seeking to model the biological and chemical interactions within system operation. In an effort to address this knowledge gap, an internally consistent life cycle assessment (LCA) was conducted on a decoupled, semi-commercial aquaponics facility which produced tilapia and cucumbers. The LCA was able to quantify environmental impacts such as global warming potential (GWP), Marine Eutrophication (MEP), Freshwater Eutrophication (FWP), water depletion (WD), cumulative energy demand (CED) and land usage (LU) for one calendar year. In order to further understand the water and nutrient flows through the system, a process engineering model was constructed and calibrated based on elemental composition data of biological materials, soluble nutrient concentration, greenhouse gas emissions, water flows and feed inputs. The resultant model was utilized to understand how changes in upstream inputs affected downstream impacts. The assessment found that seasonal differences of environmental impacts existed within normal system operation stemming from operational changes as well as changes in system demands such as heating requirements in the winter and increased ventilation during the summer months. Utilizing the process model for scenario analyses found that sufficient nutrients exist for further plant production which could lower eutrophication environmental impacts.