A new CNG bus, under the above assumptions, would produce approximately 38 metric tons of CO2e per year.
If all 49 Unitrans buses remain CNG buses, the emissions would be approximately 1856 metric tons of CO2e per
year. This is shown as the red bar in the bottom of Figure 4.
If charged on the WAPA grid, each electric bus will produce approximately 11 metric tons of CO2e a year, a
savings of 27 metric tons of CO2e emissions when compared to a single CNG bus. If the 5 buses to be replaced
in 2016 are electric buses, the emissions will be approximately 1720 metric tons of CO2e per year. With 13 electric buses in the 2019 scenario emissions will be approximately 1504 metric tons of CO2e in a year. Finally, if all 49 buses are replaced with new electric buses and charged on WAPA power, fleet emissions will be approximately 529 metric tons of CO2e in a year.
For each scenario, the GHG savings over the 12-year life span is calculated and are shown in Table 4 below.
The savings are measured against the business as usual scenario where all buses are to be replaced with new
CNG buses.
The existing UC Davis Blend is the most likely charging source for Unitrans. In this scenario, a single electric
bus charged will emit approximately 5 metric tons of CO2e in a year. This scenario provides a reduction of 33
metric tons of CO2e in a year when compared to the currently used CNG buses and 6 metric tons CO2e when