The government should continue to back the development of gas-powered trucks, according to a DfT study.

The study found that Euro-6 dedicated gas powered trucks produce almost half as much nitrogen oxides (NOx) and less than one third of nitrogen dioxide (NO2) than diesel powered Euro-6 trucks.

The study, Emissions Testing of Gas-Powered Commercial Vehicles,  carried out by the DfT and the Low Carbon vehicle Partnership, also found evidence that diesel powered Euro-6 vehicles are pumping out “higher than expected” nitrous oxide (N2O) emissions and called for further investigations.

The study tested a range of both dedicated and dual fuel trucks running on “natural gas”.

The tests found that Euro-6 dedicated gas vehicles produced  NOx emissions of around 135 mg/km, on average, compared to an average of around 230 mg/km  from the Euro-6 diesel comparators.

The vehicles also produced around 20 mg/km of NO2 emissions, less than one-third of the 78 mg/km produced on average by diesel comparators. They also produced “very little” methane.

The dual-fuel diesel and natural gas system retrofitted to a Euro-6 diesel vehicle for the study did not perform as well. It delivered increases in average NOx emissions and hydrocarbon (THC) emissions in dual-fuel mode compared to its diesel-only mode. Carbon monoxide (CO) emissions were lower though.

The dual-fuel diesel and LPG system retrofitted to a Euro-6 diesel vehicle performed better, producing lower NOx emissions in its dual fuel mode compared to its diesel-only mode, although CO and THC emissions increased.

The study concluded that dedicated gas vehicles “have potential to deliver significant greenhouse gas savings”.

“DfT should therefore continue to support the development of gas vehicle infrastructure and gas-powered vehicles, particularly dedicated gas,” it said.