Environmental life cycle assessment of lettuce production in a container-based vertical farm

Summary Vertical farms have expanded rapidly in recent years as an approach to secure more sustainable and resilient food provisioning worldwide. However, few sustainability assessments of vertical farms are available to validate such claims. This study aims to provide an environmental life cycle assessment of a container vertical farm employed by IKEA in Sweden to provide the store cafeteria with fresh lettuce. To assess the environmental performance of this system, a life cycle assessment (LCA) was conducted to assess the overall impact of producing 1 kg of lettuce supplied to the cafeteria. The LCA also highlighted key processes for improvement and compared conventional sourcing. The vertical farm had greenhouse gas (GHG) emissions of roughly 1.24 kg CO 2 -eq. kg -1 lettuce. The largest impacting processes were the energy demand for light-emitting diodes and the ventilation system, which contributed largely to all impact categories assessed. The results were also found to be sensitive to the choice of life cycle inventory data, e.g., the electricity mix. For example, employing the Nordic electricity mix could increase GHG emissions by 18%. A future scenario for using farm and cafeteria wastes for circular nutrient solutions was reviewed, but no significant benefit was found. Assessments and comparisons to conventionally imported lettuce were also conducted, illustrating that the vertically farmed lettuce had similar, or lower, GHG emissions compared to imported lettuce in most months. However, domestic production had lower impact, but was only available in the summer months, suggesting sourcing should be considered seasonally. In conclusion, despite its high energy demand, the vertical farm can supply lettuce with comparable emissions to imported lettuce. The findings shed light on the sustainability and viability of local food provisioning for the life cycle assessment and controlled environment agriculture fields.