Evaluation of environmental and economic implications of a cold‐weather aquaponic food production system using life cycle assessment and economic analysis

Abstract

Aquaponics, in which fish and plants are grown in a symbiotic closed-loop industrial metabolism, are promising test beds to implement industrial ecology in food production at a commercial scale. These systems have the potential to enhance the environmental and economic performance of aquaculture systems by reducing the overall burden on natural ecosystems (i.e., reducing resource and emission-based impacts per unit of food produced). To holistically evaluate the environmental and economic implications of aquaponics, specifically in a cold-weather climate, Life Cycle Assessment (LCA) and Economic Analysis (EA) were performed on a Midwestern United States aquaponic system, using data from 3 years of annual operation cycles with varying fish species production; tilapia, conventional walleye, and hybrid walleye. For the LCA, environmental impacts were quantified using 10 midpoint indicators. Assessments indicated that 1-kg production of live-weight tilapia, conventional walleye, and hybrid walleye resulted in 20.2-13.8-11.7 kg CO 2 -eq, 23.0-7.8-3.9 g N-eq, and 0.2-0.3-0.4 kg SO 2 -eq, consecutively, using the investigated system. The most sensitive parameters for environmental impacts were heat, aquafeed, electricity, and infrastructure (in all scenarios).For EA, benefit to cost ratios (BCRs) and three other widely used indices were analyzed for production cycles. The BCRs were 0.47, 1.16, and 1.75 for tilapia, conventional walleye, and hybrid walleye, respectively (using a 10% discount rate and a 20-year horizon), highlighting the necessity of optimizing both cash inflows (e.g., energy costs) and outflows (plant and fish revenues) to achieve practical enhancement of return on investments. The major cost contributors were infrastructure, labor, and heat (contributing to >89% of total costs for all cycles). Suggested steps for in-effect improvement of the investigated aquaponic system's environmental and economic favorability include heat and infrastructure optimization by (a) applying effective heating strategies (e.g., advanced insulation techniques), and (b) expanding the system's operational lifespan (e.g., prevention of waste accumulation).

Life cycle assessment of a retail store aquaponic system in a cold-weather region

“…(SF) was also calculated by dividing the relative variation of the results by the relative change in input data (Ghamkhar et al, 2020(Ghamkhar et al, , 2022. For input parameters with a SF of <0.1 in all impact categories (i.e., changing the input parameter by ±10% will lead to <1% change in the results), the impact results are excluded, and the parameter is thought to be less influential.…”

“…Electricity is widely regarded as the most significant contributor to the impact of aquaponic systems (Hindelang et al, 2014;Boxman et al, 2016;Maucieri et al, 2018;Jaeger et al, 2019;Verdoodt, 2019), with more electricity required in cold weather aquaponics (Chen et al, 2020;Ghamkhar et al, 2020Ghamkhar et al, , 2022Valappil, 2021) due to lower temperatures and shorter daylight hours (Valappil, 2021). Similar results were observed in this study, with electricity consumption (primarily for lightning) accounting for more than half of the impact in nearly all categories.…”

“…In terms of heating, the contribution reported in this study was lower than other cold-weather aquaponics research, which can also be attributed to the heating source. For example, Ghamkhar et al (2020Ghamkhar et al ( , 2022 aquaculture in Sweden have been found (see e.g., Nilsson and Martin, 2022). Further reduction in heating demand can be achieved through better insulation and effective space heating through optimization of the volume of the aquaponic system (reducing unnecessary space) (Ghamkhar et al, 2022).…”

“…For example, Ghamkhar et al (2020Ghamkhar et al ( , 2022 aquaculture in Sweden have been found (see e.g., Nilsson and Martin, 2022). Further reduction in heating demand can be achieved through better insulation and effective space heating through optimization of the volume of the aquaponic system (reducing unnecessary space) (Ghamkhar et al, 2022). Heating can also be recycled from exhaust heat in nearby buildings or factories, including the refrigerated cooling rooms in the adjacent supermarket as suggested by Körner et al (2021).…”

“…Cold-climate countries have lower temperatures and shorter daylight hours, resulting in aquaponics requiring more energy to operate, which can significantly increase their environmental impacts (Valappil, 2021). While several studies have been conducted on cold-weather aquaponics (Cohen et al, 2018;Ghamkhar et al, 2020Ghamkhar et al, , 2022Körner et al, 2021;Valappil, 2021), they are based on theoretical or smallscale applications.…”