دانلود رایگان مقاله انگلیسی روشی برای تجزیه و تحلیل سیستم های حمل و نقل دریایی در رویکرد چرخه زندگی - الزویر 2017

ABSTRACT

The International Maritime Organization considers decarbonizing international shipping an important and necessary step towards a sustainable global trade economy. There have been commendable studies focusing on nearly all stages of maritime transport from shipbuilding, to operation and maintenance, to engine performance optimization, to fuel options, and to dismantling and recycling, but the number of whole system level life cycle analyses (LCA) on maritime transport is far less than that on energy and goods production. This scarcity highlights the need for more independent studies to enrich the LCA literature on shipping. In response, we propose a method that adapts existing methods for the analysis of energy and goods producing systems. This approach provides crucial continuity in the serial development of a generic process chain analysis framework to ensure consistency in system and boundary formulations. Findings from the case study suggest that “slow-steaming” may not always be desirable and that 12 knots could be considered as a reference optimum speed for tankers of all size categories. Cruising at 12 knots over selected routes between top oil import and export countries, a reference range of life cycle carbon emission factors is found to be 6–9 mg of carbon dioxide for moving 1 tonne of crude oil over 1 km distance (mg-CO2/t-km). These developments demonstrate the ability of the proposed method to provide independent assessments on the life cycle carbon emissions of maritime transport systems and to derive new and/or alternative insights on the decarbonizing measures conceived by earlier studies.

6. Conclusion

We have demonstrated two key contributions in this study. The first and most important contribution is the further development of a PCA method for analyses of life cycle systems providing services. This is a significant and concluding step for the serial developments of the PCA method developed in 2014. The serial developments up to the present study have transformed a generic PCA method for analysis of energy producing systems to manufacturing systems, and to service providing systems. The serial developments and particularly the developments presented in this study have demonstrated the advantages of the quantitative formulations in deriving the system and boundary conditions. More importantly, this study represents the completion of the first stage of a larger study for the development of a global LCA model, which is recommended as future research works.

The next contribution lies with the new insights we have derived from the case study. Findings from this study show that indiscriminate speed reduction is not always desirable. Although the absolute quantity of the life cycle carbon emissions is reduced with reductions in ship speed, the total amount of crude oil transported over the tanker’s life time is also reduced. In effect, the energy and carbon efficiency of crude oil transport is also lowered if the ship speed is too low. When measured by the amount of carbon emissions released as a result of moving one tonne of crude oil over a distance of 1 km (mg-CO2/t-km), findings from this study suggest 12 knots as a reference speed at which the life cycle energy and carbon efficiency of crude oil transport is optimized. Using the reference optimum speed of 12 knots, we find that 5–10 mg-CO2/tkm can be used as a reference range of life cycle carbon emission factors for crude oil transport.