Decarbonizing bus and rail systems is central to Sustainable Development Goals (SDGs) 3, 7, 9, 11, and 13. This review combines a bibliometric analysis of 616 unique records retrieved from Scopus, Web of Science, and IEEE Xplore (2000 to 2025) with a structured synthesis of 20 focal studies selected through PRISMA-style screening, and places advanced biofuels, hydrogen, and synthetic fuels (e-fuels) on a common evidence footing that includes battery-electric buses as the benchmark. Hydrogen dominates the literature, whereas direct bus and rail applications of synthetic fuels remain untested. Waste-based biomethane and hydrotreated vegetable oil deliver greenhouse gas (GHG) savings of about 71 to 88 % relative to fossil references (in Turin, fleet emissions fall from 85.5 to 21.3 to 63.4 gCO₂ per passenger-km), whereas crop-based pathways achieve roughly 33 to 58 % before indirect land-use change. Battery-electric buses reach 63 to 76 % lower life-cycle GHG emissions than diesel on the EU grid and up to 92 % with renewable electricity, at the lowest reported cost (EUR 0.58 to 0.91 per km in an Italian case, against EUR 1.75 to 2.15 for fuel-cell buses). Fuel-cell buses save 15 to 33 % with fossil hydrogen and up to 89 % with renewable hydrogen, while using about three times more energy per kilometre than battery buses. Synthetic fuels achieve 50 to 70 % well-to-wheel savings in hybrid heavy-duty engines but require 2 to 14 times more electricity than direct electrification. We translate this evidence into a trigger-based decision framework: battery-electric operation by default; hydrogen where long range or non-electrified rail coincides with low-emission supply; biofuels as fleet-life-bound bridging options; and e-fuels for legacy niches. The indicative sequencing (biofuels to 2030, hydrogen scale-up in 2030 to 2040, selective e-fuel use after 2040) is conditional on these triggers. Coverage gaps are substantial: no focal study examined Sub-Saharan Africa or South Asia.

Title

Sustainable Energy Technologies and Assessments

Publisher

Elsevier

Publisher Country

Netherlands

Indexing

Scopus

Impact Factor

6.4

Publication Type

Both (Printed and Online)

Volume

95

Year

2026

Pages

105501