Environmental sustainability of alternative marine propulsion technologies powered by hydrogen-a life cycle assessment approach

Shipping is a very important source of pollution worldwide. In recent years, numerous actions and measures have been developed trying to reduce the levels of greenhouse gases (GHG) from the marine exhaust emissions in the fight against climate change, boosting the Sustainable Development Goal 13. Following this target, the action of hydrogen as energy vector makes it a suitable alternative to be used as fuel, constituting a very promising energy carrier for energy transition and decarbonization in maritime transport. The objective of this study is to develop an ex-ante environmental evaluation of two promising technologies for vessels propulsion, a H-2 Polymeric Electrolytic Membrane Fuel Cell (PEMFC), and a H-2 Internal Combustion Engine (ICE), in order to determine their viability and eligibility compared to the traditional one, a diesel ICE. The applied methodology follows the Life Cycle Assessment (LCA) guidelines, considering a functional unit of 1 kWh of energy produced. LCA results reveal that both alternatives have great potential to promote the energy transition, particularly the H-2 ICE. However, as technologies readiness level is quite low, it was concluded that the assessment has been conducted at a very early stage, so their sustainability and environmental performance may change as they become more widely developed and deployed, which can be only achieved with political and stakeholder's involvement and collaboration.

Automated summary

Shipping is a major contributor to global pollution, and finding sustainable alternatives for maritime transport has become crucial in the fight against climate change. This study conducted a life cycle assessment of two promising propulsion technologies for vessels, indicating their potential to promote energy transition. However, as these technologies are still in early stages of development, their sustainability and environmental performance may change with further advancements and the involvement of stakeholders.