Comparison Well-to-Tank

Emissions for the different vehicles (diesel and natural gas; hydrogen fuelled fuel cell vehicles emit no harmful emissions) were calculated using two tools, Copert [6] for Diesel vehicles and Mobile 6 [7] for CNG vehicles.

Consumption, mileage values and vehicle characteristics where obtained directly from STCP.

3.2.1. Hydrogen Vehicles

For the hydrogen vehicles an autonomy of 200km was accepted with the consumption of 40 kg of hydrogen (reference value suggested by DaimlerChrysler, road test confirm this value as a good estimate) [9]. Final energy consumption is 23,9 MJ/km.

3.2.2. Diesel Vehicles

For Diesel vehicles, the results for a Euro III vehicle are presented in Table 13.

Table 13. Results for a Euro III diesel bus operating in regular service in Porto.

Energy consumption

18,4 MJ/km


l,340E+03 g/km


3.000E-02 g/km


8,600E-02 g/km

C02 equivalent

l,370E+03 g/km