Vertical farming as a land sparing strategy: GHG implications for UK agricultural landscapes.

Growing pressure on UK land, driven by demands for food production, renewable energy, biodiversity recovery and climate mitigation, is intensifying competition for limited land. Vertical farming (VF) offers a land-sparing strategy: by relocating crop production indoors and achieving extremely high yields per unit area, VF can free agricultural land for other uses. However, VF has high greenhouse gas (GHG) emissions compared to traditional field farming due to intensive electricity demand, so its environmental value depends on whether land-sparing outcomes can offset production-stage impacts. This study provides the first UK-wide, full-system assessment of lettuce production, comparing business-as-usual field farming with national-scale VF and alternative uses of spared land. A primary-data life cycle assessment (LCA) quantifies the impacts of VF; a separate primary-data LCA of field farming incorporates DNDC-modelled national soil emissions; and the Land Use Net-Zero Advisor (LUNA) evaluates the GHG, land-carbon and energy implications of repurposing spared land for solar, wind, afforestation, agroforestry and bioenergy. VF reduces land demand by 93% but has higher GHG emissions per-kg than field systems. System-level outcomes depend on how spared land is used. Solar energy provides the strongest mitigation, fully offsetting VF's operational emissions and reducing total system impacts below the field baseline. Forestry and agroforestry generate positive land-carbon outcomes but more modest GHG reductions. Across all scenarios, peat soils dominate land-carbon losses, underscoring the need to avoid land-use change on peat and prioritise restoration. Overall, VF's environmental value arises from the land-use transitions it enables. When incorporated into multifunctional land-use planning, VF can support domestic food production while facilitating renewable-energy deployment and ecosystem restoration within a highly constrained UK land system.