Life cycle climate performance of urban plant factory versus rural greenhouse under China’s power-grid decarbonization: considering short-lived methane and nitrous oxide emissions

Abstract

Plant factories can potentially enhance the climate resilience of urban vegetable production by reducing the losses from climate hazards but generate high climate burdens - due to consuming carbon-intensive power generated by coal combustion with upstream methane emissions - unlike rural traditional sunlight greenhouses with nitrous oxide emissions. Here, we compared the life cycle Global Warming Potential (GWP) and Technical Warming Potential (TWP) metrics of lettuce production by plant factory and greenhouse, and explored the effect of power grid decarbonization on the climate performance of the cultivations. Results show that in the baseline scenario using the southern Chinese grid, the 100-year GWP of plant factory cultivation (14.9 kgCO2e kg-1) is over 50 times higher than that of the greenhouse (0.27 kgCO2e kg-1). The nitrous oxide emissions contribute 14% to the GWP of greenhouse, while methane contributes 16% to that of plant factories, which can be reduced to ~4% under a high grid decarbonization scenario in 2050. Electricity consumption (fertilizer and polyethylene film applications) shares 43%-99% (80%-89%) of the GWP of plant factory (greenhouse) cultivations. Grid decarbonization decreases the TWP metrics over time, meaning a rising climate advantage for plant factories. However, plant factories still fail to compete with greenhouses in mitigating climate change (with TWP ranging from 5-66), except if hydropower were fully deployed. Our findings add knowledge about climate-friendly and resilient vegetable supplies under China’s grid decarbonization efforts.