Natural gas contains less carbon than traditional hydrocarbon fuels and therefore emits much less CO2 as a vehicle fuel: between 25 and 30 percent less in passenger cars and light commercial vehicles and 10 to 20 percent less in trucks and buses. The full potential of gas engines has not been deployed, yet. Optimised gas engines (using direct injection and higher compression ratios) will become as energy efficient as diesel engines, meaning another 10-20% of CO2 savings can be achieved. Natural gas blended with biomethane or synthetic gas (power to gas) from renewable sources can further diminish CO2 emissions significantly (up to 95%).
|CO2 emissions of different fuels (source: IPCC)||Pollutants: NGV values vs EU limits (source: OEMs)
Natural gas, biometahne and synthetic methane contain virtually no particulate matter (PM) and have low emission levels of nitrogen oxides (NOx), making it an ideal fuel for extensive use in urban areas. Methane as a vehicle fuel emits up to 95 percent less PM and up to 70 percent less NOx compared to the very strict European emission standards for new heavy duty vehicles (Euro VI) and light duty vehicles (Euro 6). Exhaust gases from natural gas engines are also free of other harmful and carcinogenic pollutants. CNG and LNG technology is very mature and simple (using a 3-way-catalyst) and does not require further chemical treatment (e.g. Adblue injection) to meet emission limits. Gas engines have thereforen an economic advantage over diesel engines, which require a costly and complicated emissions treatment system connecting several catalysts (SCR = Selective Catalytic Reduction). Engines on methane are also much quieter than engines on traditional fuels, up to 50 percent.
Gas engines meet the highest safety standards, systems are tight and robust. Natural gas is lighter than air and can be used in ventilated car parks. Fuelling methane is as easy and quick as filling up with petrol or diesel.