Marine fuels are the main sources of pollution from shipping industry. Hydrogen and ammonia have been suggested to be alternative fuels for shipping as these two fuels do not emit carbon dioxides in the combustion process. This study employed life cycle assessment method to compare the environmental performance of propulsion systems using hydrogen and ammonia as marine fuels to fossil fuels. 2-stroke and 4-stroke engines of tankers using fossil fuels were chosen as base case scenarios. Alternative scenarios using ‘green’ and ‘blue’ hydrogen and ammonia with the support of pilot fuel were then compared to the base case scenarios. While the performance of the coming combustion concepts for hydrogen and ammonia engines are still unknown, preliminary estimations were used in this study. The results showed that hydrogen and ammonia could substantially reduce the global warming potential, compared with the fossil fuel scenarios. Hydrogen and ammonia are also expected to be highly effective in cutting down the particulate matter and the emission of black carbon.

Life-cycle assessment has been widely applied in many industry sectors for years and there are some applications of this method in the shipping sector. Fuel consumption and material consumption are considered as crucial factors in the life cycle of ship. This study uses the life-cycle assessment method to show the effects of fuel consumption reduction and light displacement tonnage on the environmental performance of ships. This is done by comparing the environmental impacts of 25 investigated scenarios with different fuel consumption and light displacement tonnage. CML2001 methodology is used to evaluate the impact assessment and the results are calculated using GaBi software. The results show that fuel consumption reduction could cut down the environmental impacts. However, some scenarios are not environmentally beneficial due to the increase in light displacement tonnage. The effects of fuel consumption and light displacement tonnage on 12 CML2001 environmental indicators are different. It is recommended that the life-cycle assessment method should be used to fully assess the environmental impacts of ships before applying any techniques in order to achieve the environmental benefits.

In this study, the life cycle assessment (LCA) was used to compare the environmental performances of a conventional bulk carrier (baseline vessel) and a wind-energy-optimised bulk carrier equipped with modern on-board technologies working in synergy (future vessel). Fossil fuels was used for the baseline vessels, whereas the future vessel used liquefied biogas (LBG) and hydrotreated vegetable oil (HVO) as marine fuels. The entire life cycle phases of the vessels, namely, construction, operation, maintenance, and end-of-life, were included. The results showed that the future vessel could reduce 31.23% energy consumption, compared to the baseline model. Furthermore, the significant reduction in CO₂ (48.6%), NO_X (88.6%), SO_X (100.0%), and black carbon (94.0%) in the tank-to-wake phase was achieved owing to energy-saving technologies working in synergy and alternative fuels. This study emphasizes the vital role of energy efficiency, technologies, and alternative fuels to achieve the zero-emission ambition of the maritime industry. Furthermore, the impacts of ship construction, maintenance, and end-of-life need to be fully considered in order to decarbonize vessel from a life cycle perspective.

Seaborne transport plays an important role in global transportation, and ships’ emissions are worth considering. By applying life cycle assessment method, the environmental impacts of ships could be evaluated. Life cycle assessment is an effective tool as this method provides a holistic perspective of a product or a service in its life cycle. In an attempt to clarify emissions released from the cradle-to-gate life cycle of ships, especially from processes in shipbuilding which were not considered adequately from some previous studies, this study conducts life cycle assessment method to assess the environmental impacts of a Panamax bulk carrier from raw material extraction to shipbuilding phase. In order to clarify life cycle emissions, some helpful mathematical formulas are also established. Ten environmental categories of CML 2001 life cycle impact assessment methodology that are relevant to the marine context are chosen for evaluating the environmental impacts. To obtain emission inventory and impact assessment results, a life cycle assessment software—GaBi—has been used. The results show that material extraction and production phase accounts for more than 85% carbon dioxide, carbon monoxide, nitrous oxide, and methane, while shipbuilding phase is responsible for 99.91% volatile organic compounds, 36.08% non-methane organic compounds, and 26.76% particulate matter emissions. In relation to environmental indicators, material consumption is much more significant than other processes and accounts for more than 86% of values of 10 environmental categories. This study is useful as it provides necessary information for life cycle assessment in the shipping industry in the future.