Life cycle emissions of electric, hydrogen, and fossil-fueled heavy-duty trucks: Trade-offs in CO2, CH4, and NOx reductions

Heavy-duty vehicles produce approximately one-third of road transport greenhouse gas emissions and remain a critical bottleneck in transport decarbonization. Prior life cycle studies have focused on a single fuel or pollutant, leaving a gap in the joint assessments of carbon dioxide, methane, and nitrogen oxides across hydrogen routes and operationally distinct vehicle classes. This study applies GREET 2023 within the ISO 14040 framework to a well-to-wheels life cycle assessment of long-haul trucks, refuse trucks, and intercity buses operated on low-sulfur diesel, liquefied natural gas, methanol, electricity, and hydrogen from steam methane reforming, biomass gasification, and solar or nuclear electrolysis. Steam methane reforming hydrogen produces 1105 g of carbon dioxide per km for long-haul trucks, whereas nuclear electrolysis reduces this to 16 g per km. Liquefied natural gas reduces carbon dioxide by 8% for refuse trucks and 5.6% for long-haul trucks and lowers nitrogen oxides by 31%–33%. The findings establish heavy transport decarbonization as a portfolio problem in which renewable hydrogen offers the strongest long-term performance subject to infrastructure expansion, while liquefied natural gas serves as a transitional fuel conditional on supply chain methane management.