As Project Manager of one of the largest electric bus fleets in Europe for six years, I strongly refute the figures used in Energy on the Move (routeone, 15 February) to calculate the carbon footprint of electric buses, which is quoted as 0.7793kg/km.
I have calculated the economy (derived from vehicle telemetry measurements) of two types of electric bus in our fleets:
Our BYD fleet over a week. It is in the region of 1kWh/km, giving a carbon footprint of 0.680kg/km
Two of our Optares (which form the majority of our 58-bus fleet and have a battery pack size of 100kW/h). Energy consumption is 0.8kW/km and the carbon footprint is 0.523kg/km.
To put this into context, a Euro 5 average diesel equivalent bus produces well-to-wheel emissions of 0.998kg/km of CO2.
Additionally, the published figures do not take into account the impact of regenerative braking. Our telemetry shows that around 35% of the energy used by our electric buses is regenerated energy. That has a significant impact on any calculations, further lowering greenhouse gas emissions, and it should not be ignored.
I’ll leave it to you to recalculate your figures using real-world information, but let’s not forget, all vehicle exhaust emissions are harmful, except those from hydrogen fuel cells.
It is better that these emissions are produced away from people, and with the benefit of flue gas after-treatment at power stations, rather than in densely populated areas.
Steve Cornes
Electric Bus Project Manager
Nottingham City Council
