Hydrogen and electric buses are considered effective options for decarbonizing the public transportation sector, positioning them as a leader in this transition. This study models the environmental and economic performances of a set of bus powertrain technologies, considering a real case-study of suburban public transport in Italy, and including fuel cell electric vehicles (FCEV), battery electric vehicles (BEV), biomethane-powered vehicles (CBM), natural gas (CNG), and diesel buses. The environmental performances of FCEV and BEV are significantly influenced by the energy source used for hydrogen production or battery charging. Specifically, using the electricity mix for FCEV leads to the highest greenhouse gas emissions and fossil fuel demand. In contrast, BEV show better environmental performance than conventional powertrains, especially when powered by photovoltaics. When powered by photovoltaics, BEV reveal similar results to FCEV in terms of environmental impacts, except for resource depletion, where both perform poorly. Transitioning from diesel to BEV or FCEV can enhance local air quality, regardless of the energy source. The economic analysis indicates that FCEV are the most expensive option, followed by BEV, both of which are currently costlier than diesel and CNG systems. CBM from waste streams emerges as a cost-effective and environmentally friendly solution. This study suggests prioritizing biomethane derived from biowaste, manure, and residual biomass (excluding energy crops) as a part of the fuels for public transport decarbonization in the EU to advance EU decarbonization goals, despite limitations due to resource availability. Furthermore, BEV powered by renewables should be prioritized whenever their range is adequate.∗