A study on life cycle assessment of energy consumption and CO2 emissions in the manufacturing and transportation processes of nitrogen and phosphate fertilizers
2001
Kobayashi, H. (Ibaraki Univ., Ami (Japan). Faculty of Agriculture) | Sago, R.
In order to apply the LCA method in evaluating environmental measures in agricultural activities, the first task is to draw up scenarios of alternatives for problem solving and subject them to analysis. Secondly, processes and items related to load calculation of life cycle need to be selected and basic data prepared. Then environmental loads produced throughout the life cycle for each scenario need to be calculated. In this paper, based on the assumption that the Life Cycle Assessment (LCA) would be used to evaluate measures to reduce environmental loads discharged in the process of agricultural nutrient input, attempts are made to calculate energy consumption and CO2 emissions throughout the life cycle of chemical fertilizer (nitrogen fertilizer, phosphate fertilizer, compound fertilizer and coating fertilizer) productions and transportations, which will provide basic data. The life cycle energy (LC-energy) in the manufacturing of urea, ammonium sulfate, diammonium phosphate (DAP), compound fertilizer and coating fertilizer were found to be 22.3MJ per 1kg of fertilizer (48.6MJ/kg-N), 4.3MJ/kg (20.5MJ/kg-N), 13.2MJ/kg (28.6MJ/kg-P), 2.0MJ/kg and 1.9MJ/kg respectively. Life cycle CO2 (LC-CO2) were 732g-CO2 per 1kg of fertilizer (1.59kg-CO2/kg-N), 262g-CO2/kg(1.25kg-CO2/kg-N), 894g-CO2/kg (1.94kg-CO2/kg-P), 142g-CO2/kg and 137g-CO2/kg respectively. Percentages of CO2 emitted during the transportation stage were approximately 2% for urea and 17% for DAP. In the production of DAP, about 16% of LC-CO2 was generated at the material collection stage. LC-energy figures obtained in this analysis are considered reasonable in comparison with existing figures.
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