Life Cycle CO2 Emissions Analysis of a High-Tech Greenhouse Horticulture Utilizing Wood Chips for Heating in Japan

High-tech greenhouse horticulture offers efficient crop cultivation that is unaffected by outdoor climate. However, compared to conventional cultivation systems, energy requirements, such as greenhouse heating and control, are larger, and concerns about the associated increase in CO2 emissions exist. Although several previous studies have analyzed CO2 emissions from high-tech greenhouse horticulture, few have covered the entire life cycle. This study aimed to analyze CO2 emissions from high-tech greenhouse horticulture for tomatoes in Japan across the entire life cycle. A hybrid method combining process and input–output analyses was used to estimate life cycle CO2 (LC-CO2) emissions. The emission reduction potential of replacing liquefied petroleum gas (LPG) for greenhouse heating with wood chips was also examined. The results show that LC-CO2 emissions were estimated to be 3.67 kg-CO2 per 1 kg of tomato, 55.6% of which came from the production and combustion of LPG for greenhouse heating. The substitution of LPG with wood chips has the potential to reduce LC-CO2 emissions by up to 49.1%. However, the improved LC-CO2 emissions are still higher than those of conventional cultivation systems; thus, implementing additional measures to reduce LC-CO2 emissions is crucial.