Carbon footprint analysis of non-fossil heating strategies for agricultural greenhouses in Switzerland

• Heating and lighting impact carbon footprint based on location and scheduling. • Biogas CHP can achieve net-negative emissions in greenhouse. • Non-fossil heating cuts emissions from 1.08 to 2.75 to –1.7–0.83 kg CO 2 -eq/kg. • Biogas CHP and ORC cover both heat and electricity for greenhouse operations. The use of fossil fuels to heat greenhouses results in a substantial carbon footprint. This study uses life cycle assessment to quantify and analyze the carbon footprint of greenhouse tomato production in six regions of Switzerland, considering four non-fossil-based heating strategies: (1) wood chips boiler, (2) heat from biogas Combine Heat and Power (CHP) system, (3) waste heat recovery systems (direct and Organic Rankine Cycle (ORC) integrated), and (4) heat pumps. The results are compared with two conventional fossil-based strategies, including (5) natural gas boilers and (6) natural gas CHP for two greenhouse scheduling practices (with and without winter months). Spatiotemporal modeling was employed to estimate heat and supplementary lighting demand of the specific regions. The results show the importance of non-fossil heat strategies that generate electricity in addition to providing heat for greenhouses. Biogas CHP (−1.69 to −0.20 kg CO 2 eq./kg crop) and waste heat ORC systems (0.26–0.47 kg CO 2 eq./kg crop) show the lowest carbon footprint of tomatoes in each region. As expected, all non-fossil fuel strategies (−1.69 to 0.83 kg CO 2 eq./kg crop) result in lower carbon footprints than fossil fuel strategies (1.08–2.28 kg CO 2 eq./kg crop). Also, all non-fossil fuel strategies (excluding heat pumps) can compete with the carbon footprint of unheated greenhouse crops imported from Spain, Morocco, and Italy. The findings offer a roadmap for environmental policymakers on the technological impacts on greenhouse production and the influence of plant scheduling on environmental impacts.