Pathways to net-zero farming: a carbon footprint comparison of vertical versus traditional agriculture

Agriculture is one of the leading causes of climate change, contributing nearly a quarter of global greenhouse gas emissions. Indoor vertical plant farming (VPF) is a novel form of agriculture offering space savings, water efficiency, and hyper-local production. A significant caveat is the associated CO₂ emissions from energy consumption. We conduct a carbon life-cycle analysis of lettuce production comparing imports from a Spanish field-based farm with hydrogen fuel cell-powered vertical farm in a UK context. We examine the implications of energy source trade-offs and the effects of deforestation. Experimental data using blue hydrogen energy shows emissions for VPF as 3.79 kg CO₂e kg^-1 without and 4.45 kg CO₂e kg^-1 with the impact of deforestation considered. Associated emissions for field-based imported lettuce are 1.14 kg CO₂e 
kg^-1 and 5.05 kg CO₂e kg^-1 without and with deforestation, respectively. Sensitivity analysis of energy sources in VPF shows tidal energy reduces emissions to 1.57 kg CO₂e kg^-1 with deforestation considered, a third of the emissions from conventional agriculture. Wind, tidal and geothermal energies also show promise for low carbon footprints. The results show that VPF with renewable energy sources could provide a lower carbon footprint than imported lettuce from a field-based farm. We believe this is the first attempt to make such a comparison based on real-world data from a VPF and consideration of the effects of deforestation.