Environmental impact assessment of local decoupled multi-loop aquaponics in an urban context.

Fresh vegetables available on Northern European markets usually originate from a high number of sources. Environmental impacts for these goods typically arise from the resources used in production and the long-distance transport in air-conditioned trucks. As such, environmental impacts are mainly attributed to direct energy consumption, water use and nutrient supply. The aim of this paper was therefore to investigate and evaluate possible solutions to reduce the environmental impacts of vegetables available on urban markets in Northern Europe. We hypothesise that for the production of lettuce and tomatoes in Northern Europe, a 4-step solution, i.e. 1) local production, 2) climate-controlled efficient greenhouses, 3) decoupled aquaponics, and 4) combined building architecture with waste heat and green waste reuse, will enable a low environmental impact. We defined the metropole Berlin as case example, and used simulation results from a proven greenhouse simulator as input to a comparing life cycle assessment of fresh lettuce and tomato. The assessment included a list of 12 midpoint environmental impact categories, e.g. global warming potential with 100 year horizon (GWP 100 ; kg CO 2 eq.), depletion of fossil fuel reserves (FRS; kg oil eq.), and water use (WCO; m3 water). Most impact categories decreased systematically when increasing the complexity of the local vegetable production. Compared to the mix of vegetables from different locations available on the market, the complete 4-step solution reduced WCO from water consumption to water saving: i.e. from 14.2 L or 3.3 L to −10.1 L or −0.21 L per package of 500 g tomatoes or 150 g lettuce, respectively. GWP 100 and FRS were below the values of the available market mix, e.g. GWP 100 decreased with 8.7% in tomatoes and 49.9% in lettuce. In conclusion, with the right set-up, local vegetable productions in urban regions can surpass the imported mix on environmental performance in Northern Europe. [Display omitted] • Full-scale greenhouse vegetable production and aquaponics simulator was combined with LCA. • Compared to hydroponics energy consumption was reduced by 19% or 30% in tomato or lettuce. • Compared to lettuce import-mix, local aquaponics can reduce global warming potential by 50%. • Lettuce and tomato produced in multi-loop aquaponics have negative water use. [ABSTRACT FROM AUTHOR]