Decarbonizing the transportation sector is essential to achieving climate stabilization and reaching net zero greenhouse gas emissions by 2050. Hydrogen proton-exchange membrane (PEM) fuel cell vehicles (FCVs) is a promising novel solution to reach this target. There are three primary forms of hydrogen to power the PEM fuel cell vehicle: grey , blue , and green , produced from steam methane reforming (SMR), SMR with carbon capture and storage (CCS), and water electrolysis powered by zero/ low carbon energy sources, respectively. In this study, the focus is on grey and blue hydrogen due to their cost-competitiveness and technological availability. Saudi Arabia heavily relies on fossil fuels such as crude oil and natural gas as its main energy provider. As the sixth largest natural gas reserve, it has tremendous potential for natural gas development. Therefore, grey and blue hydrogen sources are considered to be more accessible and feasible for PEM fuel cell vehicle development in Saudi Arabia. Literature studies on the life cycle assessment (LCA) of heavy-duty vehicles are limited. A research gap exists in the environmental assessment of the application of battery electric (BE) and PEM fuel cell buses in Saudi Arabia, as well as the energy consumption and emissions. Furthermore, the complete LCA can be divided into two parts: fuel cycle and vehicle cycle, and only a few studies have focused on both. This study bridged these research gaps and explored the global warming potential (GWP), abiotic depletion potential (ADP), and acidification potential (AP) of using grey and blue hydrogen in PEM fuel cell vehicles operating in Makkah in Saudi Arabia. It compares the life-cycle emissions of 20 internal combustion engine (ICE) vehicles, 20 battery electric (BE) vehicles, and PEM fuel cell vehicles for heavy-duty transportation with a lifetime of 254,040 km. The emissions and energy use of refueling infrastructure for 3 types of vehicles for 5 years were also determined, as well as the emissions and energy use of hydrogen transportation from eastern Saudi Arabia to Makkah.
The emissions from upstream fuel production and delivery (or well-to-pump) are the most critical for the hydrogen PEM vehicles. This is due to the fact that the emissions in the usage phase are almost zero. Hydrogen can be produced and used inside Saudi Arabia employing gas tube trailers for fuel transport and has a potential to reduce the emissions at this stage. Blue hydrogen has most of its production emissions captured, hence it delivers lower total emissions compared to grey hydrogen. The LCA study highlights the importance of developing PEM fuel cell vehicles and provides guidelines to governments and companies for developing hydrogen PEM fuel cell vehicles in Saudi Arabia..