Book excerpt: Most heavy trucks should be fully electric, using a combination of batteries and catenary electrification, but heavy trucks requiring very long unsupported range will need chemical fuels. At the scale of heavy trucks, compressed hydrogen can match the specific energy of diesel, but its energy density is five times lower, limiting range to around 2,000 km. Scaling green hydrogen production and addressing leakage must be priorities. Hydrogen-derived electrofuels—or “e-fuels”—have the potential to scale, and while the economic comparison currently has unknowns, clean air considerations have gained new importance Decarbonized Power Options for Long-haul Commercial Vehicles discusses these energy sources as well as the caveats related to bioenergy usage, and reasons to prefer ethanol or methanol to diesel-type fuels. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2023005