Life cycle carbon emission intensity assessment for photovoltaic greenhouses: A case study of Beijing City, China

The integration of greenhouse buildings and photovoltaic (PV) power generation improves the land utilization rate and reduces carbon emissions from agricultural production. However, there is uncertainty regarding the amount of emissions that can be reduced and how to compare the carbon emissions of different PV greenhouses, particularly in terms of the life cycle. This study establishes a quantitative evaluation method for carbon emission intensity throughout the entire life cycle of PV greenhouses. First, we propose a tiered hybrid analysis method based on dynamic emission factors to improve the accuracy and boundaries of the evaluation. Second, we design two carbon-emission intensity indicators to compare and evaluate various PV greenhouses. Third, we analyze the life-cycle carbon emission intensity of three typical PV greenhouses in Beijing, China. Plastic greenhouses had the lowest carbon emissions per unit area, at 1352.47 kgCO2/m2. The multi-span greenhouses had the lowest carbon emissions per unit crop yield, ranging from 99.09 to 103.96 kgCO2/kg. PV modules can decrease greenhouse carbon emission intensity by 21.09%–43.84 %, and a set of approximate estimation equations that relate the PV module installation ratio to carbon emissions are derived. Moreover, it is established that the main emission sources include plastic usage, material transportation, electricity consumption, and temperature control. Based on the assessment results, we suggest prioritizing the selection of multi-span greenhouses under conditions of abundant land resources and investment. Alternatively, we suggest choosing plastic greenhouses made of environmentally friendly or reusable materials.