Carbon dioxide emissions from diesel and compressed natural gas buses during acceleration

Document Type

Journal Article

Publication Date


Subject Area

mode - bus, planning - environmental impact, policy - environment, technology - alternative fuels


Carbon dioxide, Greenhouse gas emissions, Traffic congestion, Bus emissions


Motor vehicle emission factors are generally derived from driving tests mimicking steady state conditions or transient drive cycles. Neither of these test conditions, however, completely represents real world driving conditions. In particular, they fail to determine emissions generated during the accelerating phase – a condition in which urban buses spend much of their time. We analyse and compare the results of time-dependant emission measurements conducted on diesel and compressed natural gas buses during an urban driving cycle on a chassis dynamometer and we derive power-law expressions relating carbon dioxide emission factors to the instantaneous speed while accelerating from rest. Emissions during acceleration are compared with that during steady speed operation.


Permission to publish abstract has been given by Elsevier, copyright remains with them.


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