Energy and exergy utilization, and carbon dioxide emission in vegetable oil production

Energy and exergy utilization and carbon dioxide emission during production of soybean, sunflower, and olive oils are assessed. In all cases, agriculture is the most energy and exergy intensive process and emits most of the carbon dioxide, and diesel is the dominant energy and exergy source. The cumulative degree of perfection (CDP) for soybean and olive oil is 0.92 and 0.98, respectively, whereas the CDP for the sunflower oil is 2.36. Decreasing diesel consumption with good agricultural practices and substituting with biodiesel from renewable resources would decrease the cumulative exergy consumption, as a result, CDP of olive and soybean oil rises to 1.6 and sunflower oil to 2.9.Major contribution to the carbon dioxide emission is due to the excessive use of fertilizers. The most energy intensive process is olive oil production. However, since the fertilizer consumption here is limited, total carbon dioxide emission is less than those of the other two processes are. On the other hand, excessive fertilizer consumption during the soybean agriculture results in a rather large CO₂ emission.