HGVs powered by liquefied natural gas (LNG) are no better for the climate than diesel trucks and pollute the air more than manufacturers claim, a report by a clean transport campaign group has concluded.

Transport & Environment (T&E) said only zero-emissions HGVs such as battery electric vehicles should be supported by lawmakers and it called for gas fuelling stations to be kicked out of EU fuel infrastructure targets and the end to government subsidies for LNG trucks.

However, the renewable gas industry heavily criticised the study and said it was poorly referenced and failed to meet necessary scientific standards.

T&E commissioned on-roads tests of Iveco’s S-Way LNG truck and a Stralis diesel model and said the analysis showed the LNG vehicle emits 13.4% more greenhouse gases over a 20-year timeframe.

It said the Technical University of Graz found that the gas truck’s emissions savings at the tailpipe were “negligible” after testing for exhaust CO2, methane and nitrous oxide and when T&E analysed methane venting and upstream greenhouse gas emissions, it claimed that over a 100-year timeframe the LNG truck emits just 7.5% less than the diesel alternative.

T&E also said that the LNG vehicle was far worse for cancer-causing particle emissions in cities and rural driving and while it accepted that the gas truck performed better than the diesel for NOx emissions, it said that it did not deliver the 90% savings that the truckmaker claimed.

Fedor Unterlohner, T&E freight manager, said: “LNG trucks are held up as saviours of air quality, but tests show they pollute far more than manufacturers claim.

“They are also a lot worse than diesel for the smallest and most harmful particles, including in city driving, where they are used for deliveries.

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“Ultimately, gas trucks are just another fossil fuel technology that can never clean up freight.”

Iveco did not respond directly to the results, but it told motortransport.co.uk that it was “fully aligned” with the comments and analysis published by the European Natural Gas Vehicle Association (ENGVA).

This pointed out that numerous studies over the last 20 years repeatedly proved that methane-powered propulsion systems were better than diesel in terms of greenhouse gas emissions.

“The claim that methane-powered vehicles produce more greenhouse gas emissions than diesel vehicles does not correspond to the state of the art,” said the ENGVA.

“Methane-powered vehicles are generally better in terms of greenhouse gas emissions than a comparable vehicle powered with diesel fuel.”

James Westcott, chief commercial officer at Gasrec, also criticised the T&E study:

“We would strongly challenge the findings of the report, which is poorly referenced, involved just two trucks – one diesel and one LNG – from a single manufacturer, and puts far too much weight on performance during stop-start journeys in rural and urban environments,” he said.

“Only last year, the £20m government-funded, three-year Low Emissions Freight Trial, from the Low Carbon Vehicle Partnership, highlighted the significant environmental and financial benefits of gas over diesel, particularly in long-haul applications – which is where the vast majority of our customers are using these trucks.”

DAF Trucks said it was regularly asked why it didn’t offer LNG and CNG engines and that the reason was that the greater efficiency of diesel engines balances out any CO2 savings gained by burning gas.

“More gas than diesel is required for a truck to travel the same distance,” it said.

“This makes the difference in CO2 emissions from ‘tank to wheel’ negligible.

“In fact, if you consider the whole cycle from ‘well to wheel’, using LNG results in higher CO2 emissions than diesel.”

Phil Moon, DAF Trucks marketing manager, said the T&E report highlighted “the negligible and ofttimes negative environmental benefits from using natural gas instead of diesel.

“And of course, gas-fuelled vehicles can incur higher ownership costs and face significant operation limitations,” he added.