Environmental life cycle assessment of a commercial aquaponic system

Abstract

This study aimed to analyse the environmental performance of a commercial aquaponic system in Sweden. The system produces rainbow trout and 40+ varieties of leafy greens, edible flowers and herbs, about 50 % of which is lettuce, in total about 1200 kgs of plants was sold in 2022. Attributional life cycle assessment was employed to assess the environmental impacts of producing rainbow trout and leafy greens, with functional unit of 1 kg of leafy greens, employing system expansion for replaced conventionally produced trout. Results show a climate change impact of 3.94 kg CO₂eq/kg plant. The results suggest that energy, infrastructure, and consumables were the main contributors to most environmental impact categories of the modelled system. Electricity contributed to 52 % of climate change impacts. Specifically, electricity used for artificial lighting represents 45 % of the electricity use. Reduced photoperiod was found to lead to reduced impact in all impact categories assessed. Another scenario explored the use of an insect-based feed using insects produced in Sweden as a possible pathway for increased circularity of the system. For the insect-based feed results depended on modelling choices (e.g. burden or no burden) for the food waste used for insect farming. Furthermore, the results were sensitive to the choice of electricity mix employed. This study advances the LCA literature in aquaponics by providing an actual case study with empirical evidence of aquaponics' sustainability and improvement pathways. The evidence shows results that existing and future aquaponics systems can use to optimise their performance and address potential trade-offs.