The food industry is a contributing factor to climate change, where innovative solutions, such as vertical farming, can be applied to promote sustainable food production. Vertical farming systems enable urban indoor farming, vertically on shelves, in controlled environments with cultivation chambers, lighting systems and usually soil-free cultivation methods (e.g. hydroponics), that are essential parts of the system. Temperature, relative humidity and artificial light are regulated to satisfy the crops needs. Hydroponic cultivation utilizes growing mediums such as rock wool instead of soil and the roots of the plants are in constant contact with the recirculating water in the system, which provides the plants with nutrients. Previous life cycle assessments of vertical farming systems, although limited in numbers,highlight the electricity consumption as the largest contributing factor to the environmental impact, as well as replacing different materials for a lower environmental impact.
This study aims to assess the environmental impacts and hot spots, through the use of life cycle assessment, on Swegreen's vertical farming system Freja, at ICA Maxi Solna. Furthermore the life cycle assessment aims to identify the phases and flows that accounts for significant environmental impact, as well as some suggestions for improvement. The vertical farming system applies the perspective of ‘cradle to use’for 30 years, not including the assembly or waste disposal phase. The use phase includes the life cycle of lettuce, from ‘cradle to grave’, not including the consumption phase. The functional unit is 1 kg of produced oak leaf lettuce, class 1,available to consumers. Data has been obtained from both Swegreen's digitized data and from a previous study conducted on Swegreen's farming system Saga. To process the data, the software SimaPro and the Ecoinvent 3.8 database was applied.
Results are analyzed with regards to the environmental impact categories ecotoxicity (freshwater), fossil resource use, acidification, climate change, land use,resource use (minerals and metals), water use and eutrophication (freshwater).Results indicate that the lettuce cultivation phase (containing electricity use) is the main hotspot of the system, followed by the raw material phase for the lettuce. Aphase that also dominates in all environmental impact categories, except for resource use (minerals and metals). Results cannot be generalized since they dependon the choice of functional unit, system boundaries and type of data. The sensitivity analysis regarding the energy production and waste disposal suggests that different alternatives cause the lowest environmental impact, depending on which environmental impact categories are considered the most important.