Benefits connected with the use of NG/biomethane

Tailpipe CO2 emissions

In real life, engine efficiencies on different test cycles will be different (compression ignition engines e.g. still with a higher efficiency than positive ignition engines) and vehicles using CNG cylinders will normally have a slight weight penalty compared to similar gasoline powered vehicles. The optimization with regard to cetane and octane ratings will also play a role. State-of-the-art NGVs achieve a 25 % CO2 benefit compared to a similar gasoline powered vehicle.

In a dual fuel vehicle with a compression ignition engine running on methane, but supported via pilot injection of diesel, the reduction of CO2 emissions compared to a standard diesel vehicle will depend upon the diesel substitution ratio (an 80 % substitution ratio would e.g. mean around 20 % reduction  of the CO2 emissions). Dedicated state-of-the-art positive ignition gas engines may presently reach around 10 % CO2 reduction in comparison to a similar diesel engine.

Technological developments and changes of exhaust emission treatment systems to meet future emission demands means that the relations quoted may shift over time. Positive ignition NG engines are likely to profit from these developments.     


Other emissions

• Uniquely low emissions of toxic or carcinogenic substances
• Almost zero particulate emissions
• No emissions of reactive hydrocarbons contributing to the formation of ground level ozone
• Reduced NOx emissions compared to compression ignition diesel engines
• Reduced noise and vibrations in comparison to compression ignition engines

Other advantages

• Much lower fuelling costs than for conventional fuels
• Offers the potential for future large scale use of renewable biomethane without any restrictions on blending ratios
• Can immediately offer large volume substitution of oil based fuels, thus reducing oil dependence