Life cycle assessment of marine power systems onboard roll-on/roll-off cargo ships : framework and case studies

Abstract

A study into the environmental impact of marine power systems was performed in proximity with the defined research objectives: (i) present an overview on Annex VI The International Convention for the Prevention of Pollution from Ships, cargo ships, marine power systems and technologies; (ii) review life cycle assessment (LCA) methodology development; (iii) develop an LCA framework for marine power systems; (iv) carry out case studies to determine environmental impact, significant components and critical processes; (v) apply scenario analysis to investigate the sensitivity of the results to selected parameters; and (vi) compare power systems under study to verify their environmental benefits. Built upon literature and the proposed LCA framework, LCA case studies on conventional, retrofit and new-build power systems were performed using a bottom-up integrated system approach, where data were gathered and LCA models were created for individual technologies using GaBi software. Life cycle impact assessment was performed using CML2001, International Reference Life Cycle Data System (ILCD) and Eco-Indicator99 to estimate the environmental impact of the systems. It was found that disposing metal scrap of significant components was the principal cause of ecotoxicity potential, which was the impact category that showed the top two highest indicator results; and operating diesel engines and auxiliary generators or diesel gensets was mainly accounted for other impact categories. When compared with the conventional system, both retrofit and new-build systems consumed less fuels and released less emissions during operation but involved more materials and energy during other life cycle phases, leading to a decline in most impact categories to the detriment of a few burdens. The life cycle of marine power systems must be planned, managed and monitored appropriately for reduced environmental implications. Further research should address limitations presented in this study and explore other factors that might affect the environmental burdens of marine power systems.