A new study by the US Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) finds that with continued improvements in vehicle and fuel technologies (in line with DOE targets and vetted with industry), zero-emission vehicles (ZEVs) can reach total-cost-of-driving parity with conventional diesel vehicles by 2035 for all medium- and heavy-duty (MD/HD) vehicle classes (without incentives).

Further, assuming economics drive adoption, the study finds that ZEV sales could reach 42% of all MD/HD trucks by 2030, reflecting lower combined vehicle purchase and operating costs (using real-world payback periods). In this scenario, ZEV sales reach more than 99% by 2045, and 80% of the MD/HD stock transitions to ZEVs by 2050, reducing CO₂ emissions by 69% from 2019.

The study finds that both battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) are viable in multiple market segments, offering alternative pathways for decarbonization.

• BEVs tend to become cost-competitive for smaller trucks before 2030 and for short-haul (<500-mile) heavy trucks before 2035.

• Hydrogen FCEVs tend to become cost-competitive for long-haul (>500-mile) heavy trucks by 2035

The study looked at three different vehicle classes—light-medium (Class 3) 10,000-14,000 lbs; medium (Class 4-6) 14,000-26,000 lbs; and heavy (Class 7-8) 26,000+ lbs—and eight different use cases/driving distances.

ZEV adoption is more rapid in lighter and shorter-distance vehicles, which also tend to be centrally fueled, reducing infrastructure risk. Based on external studies, buses are assumed to fully transition to ZEV by 2030 (100% sales).

The NREL team noted that results are highly sensitive to assumed fuel prices (both for new technologies and for existing diesel fuels). Energy management techniques, proactive utility and clean fuel investment planning, and associated policies are needed to lower final energy costs, the authors said.

The results are also very sensitive to technology improvement trajectories, adoption decision-making, and uncertain assumptions about future freight demand, logistics, and vehicle use.

Medium- and heavy-duty vehicles account for less than 5% of the vehicles on the road but produce more than 20% of the emissions from the transportation sector, which currently accounts for more than one-third of US greenhouse gas emissions.