Assessing the impact of bus technology on greenhouse gas emissions along a major corridor: A lifecycle analysis

This paper evaluates the impact of alternative bus transit technologies including compressed natural gas, biodiesel, and diesel-electric hybrid on greenhouse gas emissions along a busy transit corridor using a lifecycle analysis approach. In addition, we compare the operational emissions of buses running on these technologies using an instantaneous speed and an average speed model. Our results indicate that operational emissions make-up the largest portion of lifecycle emissions. When comparing instantaneous and average speed emissions we find that both methods produce consistent results for diesel, however, the average speed method underestimates biodiesel emissions by 21% and overestimates compressed natural gas emissions by 16%. Bus technologies ranked in increasing order of lifecycle greenhouse gas emissions are: hybrid, compressed natural gas, biodiesel, and conventional diesel.

► We conducted a lifecycle analysis of greenhouse gas (GHG) emissions for bus transit.
► Hybrid buses had the lowest lifecycle GHG emissions followed by compressed natural gas, biodiesel, and conventional diesel.
► Operational emissions make-up the largest portion of lifecycle emissions.
► Operational emissions depend on the modeling approach (average vs. instantaneous speed).