A 2017 research by Carnegie Mellon University compares life cycle agency and social costs, as well as other particular challenges for eight alternative fuel technologies for transit buses, including: conventional diesel, diesel hybrid electric, rabid-charging battery-electric, slow-charging battery-electric, compressed natural gas (CNG), liquefied natural gas (LNG), 20-percent biodiesel (B-20), and 100-percent biodiesel (B-100).

The full report is available online:  Which Alternative Fuel Technology is Best for Transit Buses?