The Power Behind the Plants: Energy Scenarios in Vertical Farming

Vertical farms are often promoted as environmentally friendly options; however, evidence on the environmental performance of commercial facilities is limited, particularly within Mediterranean climates. This study reports a cradle-to-grave life cycle assessment (LCA) of a large-scale commercial vertical farm producing lettuce in the Lombardy region of northern Italy. The functional unit was defined as 1 kg of edible lettuce. Environmental impacts were assessed applying the Environmental Footprint (EF) 3.1 characterization method across nine impact categories: climate change, acidification, terrestrial ecotoxicity, freshwater eutrophication, marine eutrophication, land use, water use, and abiotic depletion of fossil and mineral resources. The current operational configuration, based on biomethane-fueled combined heat and power (CHP) cogeneration, was evaluated against four alternative energy pathways: the Italian national electricity grid, natural gas cogeneration, renewable electricity procurement, and biomethane production from alternative feedstock compositions. The biomethane CHP scenario yielded a climate change impact of 3.02 kg CO2-eq per kg of edible lettuce, compared to 6.16 kg CO2-eq per kg under natural gas cogeneration and 6.06 kg CO2-eq per kg under the Italian grid mix. Minimum climate change impact was obtained under fully renewable electricity supply, at 1.38 kg CO2-eq per kg. Biomethane performance showed marked sensitivity to feedstock composition, with climate change impacts ranging from 3.02 to 6.44 kg CO2-eq per kg depending on organic residue and manure proportions. Although biomethane reduced climate change impacts relative to fossil-based configurations, pronounced trade-offs were identified in freshwater eutrophication and terrestrial ecotoxicity, attributable to upstream feedstock handling and digestate management. Electricity consumption for lighting, cooling, and dehumidification constituted the dominant environmental hotspot across all scenarios, while infrastructure embodied impacts represented a secondary yet substantial contributor to fossil and mineral resource depletion. Collectively, these results establish energy sourcing as the principal determinant of environmental performance in Mediterranean vertical farming, with all evaluated pathways directly actionable under the European Renewable Energy Directive (RED II, Directive (EU) 2018/2001). Direct electrification with verified low-carbon electricity delivered the greatest environmental improvements across impact categories. Where biomethane-based cogeneration is maintained, realizing consistent environmental benefits requires careful feedstock selection, stringent methane-loss control, and robust digestate management practices. Mitigating infrastructure-related burdens additionally demands targeted design optimization, responsible material procurement, and appropriate end-of-life management strategies.