This paper examines the climate impacts of trucks running on liquefied natural gas and how they compare to those using diesel fuel. The analysis considers the emissions of all greenhouse gases, not only of CO2, over the complete well-to-wheel fuel chain. The results have important policy implications.
The main findings of the study are:
- Most trucks running on liquefied natural gas (LNG) emit about the same amount of greenhouse gases as diesel trucks, despite the lower carbon content of natural gas. This is mainly attributed to the methane emissions that occur during the extraction, transportation and use of LNG.
- To better capture the climate impact of LNG trucks in the European CO2 regulations, it would be necessary to account for direct methane and nitrogen oxide emissions at the vehicle level in the certification methodology.
- Introducing stringent limits for methane and nitrogen oxide as part of pollutant emission standards could improve the GHG performance of LNG and diesel trucks.
- Road tolls should take into account all GHG emissions of trucks, instead of only CO2, to avoid inadequate incentives for LNG trucks.
- Policy instruments aimed at subsidizing LNG trucks (e.g., purchase, road-toll exemption, energy taxes) are inefficient and can even be counter-productive.
- There is little potential for using climate-friendly liquified methane (biogas, synthetic e-methane) in trucks. Renewable methane from low-carbon feedstocks is limited and there is strong competition from other applications and sectors.