Emission and Fuel Consumption Measurements for Transit Buses Running on Gaseous Fuels Using a Mobile Measurement System

The emissions of heavy-duty engines have traditionally been measured in Europe by using steady-state engine dynamometer tests. However, several studies have proved that emissions of real stop-and-go driving are much higher than the steady-state results indicate.

In this study, a mobile measurement system, located inside a vehicle, was utilized. The emissions and energy consumption of different gaseous fuel powered transit buses were measured by using two duty cycles, and the results were compared with diesel technology.

The results indicated that NO_X emissions of gaseous fuels were in the range of 30-90 % lower than diesel, depending on vehicle technology and fuel. However, energy consumption of gaseous fuels was found to be around 20-45 % higher than in the case of diesel.