When new emission legislation is introduced in the passed there has been a political ambition to promote early introduction of the new technology. For Euro V there was an exception for “Euro V incentive” engines not to meet the full demand specification concerning diagnostics and other supposedly peripheral demands in the legislation.
Now, when looking ahead towards the Euro VI legislation for buses again I hear about the demand for early introduction of the new legislation. What will the effect be on the environment?
When comparing the environmental impact of Euro V and Euro VI we can use the European directive for Public Procurement of environmentally friendly road transports where the cost for the society is monetised. (Read about the procurement here)
The contributions to e.g. health related cost from energy use, carbon dioxide, NOx, particulate matter and hydrocarbons are added to the total cost for society.
When going from Euro II to Euro III it was found that the fuel consumption increased when the NOx was brought down. For Euro VI with out knowing the details I have estimated the fuel consumption increase to 3%. Carbon dioxide will decrease with the corresponding number. For the emissions of NOx I have uses the change from 2 to 0.4 g/kWh for NOx and from 0.02 to 0.01 g/kWh for particulate mater. For the hybrid however we have found that the emissions of NOx are reduced by 50% when compared to the standard diesel bus and the hybrid can be equipped with an particulate filter reducing the particulate matter by 90%.
In the graph below we find that the Euro VI City Bus will decrease the total environmental impact by about 5% when compared to the Euro V bus, while the corresponding hybrid bus will decrease the environmental impact by about 33%.
I therefore say that for the environment, the best Euro VI incentive is a Volvo 7700 Euro V Hybrid Bus!