Comprehensive Life Cycle Analysis of Diverse Hydrogen Production Routes and Application on a Hydrogen Engine

Abstract

In the effort of achieving net-zero greenhouse gas (GHG) emissions, hydrogen is becoming increasingly relevant in several sectors such as automotive, cogeneration, maritime, off-road, and railroad. However, hydrogen can be produced from different routes involving different production processes and feedstocks. Contrarily to the key role of hydrogen in the transport sector's decarbonization, publications that claim to address the environmental impacts of hydrogen are often focused on global warming potential (GWP). This paper focuses on the environmental impacts of hydrogen production considering different production routes (i.e., steam methane reforming (SMR), SMR with carbon capture and storage (CCS), coal gasification (CG), CG with CCS, and electrolysis from fossil fuels and from renewables) and a broad set of environmental indicators. The life cycle assessment (LCA) methodology is applied in the present study with a twofold aim. The first aim is to develop the LCA models of diverse hydrogen production routes and address present and potential well-to-tank (WTT) impacts. The second aim is to apply the previous findings to develop a cradle-to-grave LCA of a hydrogen engine, serving as a case study for the automotive sector. The LCA models are developed using simapro v.9.4.0.3 as LCA software and ecoinvent v3.8 as background database. The functional units are 1 kg of hydrogen for the cradle-to-gate boundary and 1 mile of vehicle lifetime for the cradle-to-grave boundary. The traci 2.1 method developed by the U.S. Environmental Protection Agency (EPA) is used.