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

TLDR

Shipping is a major source of pollution, and hydrogen is being promoted as a promising energy carrier to reduce greenhouse gas emissions in maritime transport. The study aims to conduct an ex‑ante environmental assessment of a hydrogen polymeric electrolytic membrane fuel cell and a hydrogen internal combustion engine for vessel propulsion, comparing them to a conventional diesel engine. The assessment follows Life Cycle Assessment guidelines using a functional unit of 1 kWh of energy produced. Both hydrogen technologies show strong potential for decarbonization, especially the H2 ICE, but their early development stage means their environmental performance may evolve with broader deployment and stakeholder collaboration.

Abstract

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 H2 Polymeric Electrolytic Membrane Fuel Cell (PEMFC), and a H2 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 H2 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.