Methane's Potential As A Clean Car Fuel: Unlocking Its Power

Methane is not used as a fuel for cars because it has a high global warming potential. Methane emissions from NG-fuelled vehicles can be reduced by exhaust aftertreatment devices to low levels, but not necessarily for all engine concepts.

Methane emissions from NG-fuelled vehicles can be reduced by exhaust aftertreatment devices

Methane is a fuel with a high global warming potential and energy consumption of methane-fuelled cars is lower than that of gasoline-fuelled cars. Methane emissions from NG-fuelled vehicles can be reduced by exhaust aftertreatment devices to low levels, but not necessarily for all engine concepts.

Methane emissions from a CNG bus were around 150 mg/km in older studies and even as high as 2750 mg/km. Methane emissions from NG-fuelled vehicles can be reduced by exhaust aftertreatment devices to low levels, but not necessarily for all engine concepts.

Compressed methane (CNG, CBG): natural gas or biomethane has been compressed after processing; mainly used for vehicles and typically compressed up to 200 bar.

Liquefied methane (LNG, LBG): natural gas or biomethane has been liquefied after processing. Temperature is about -161.7 °C at atmospheric pressure and, when used as an automotive fuel, it can be stored in on-board cryogenic tanks (vacuum-isolated stainless-steel vessels), which have different operating pressure.

Methane has a high global warming potential

Methane fuelled cars have lower energy consumption than gasoline-fuelled cars because of the higher hydrogen-carbon ratio of methane (CH4) when compared to diesel (C15H28) or gasoline (C7H15). This generally leads to less or comparable tailpipe CO2 emissions with CNG as for diesel and gasoline engines depending on engine efficiency.

Methane can be stored in on-board cryogenic tanks (vacuum-isolated stainless-steel vessels), which have different operating pressures.

Methane can be produced locally and therefore distribution is different from natural gas in many respects. However, both bio-origin and fossil methane is used in compressed or liquefied state for storage and for transportation purposes. Compressed methane (CNG, CBG) is mainly used for vehicles and typically compressed up to 200 bar. Liquefied methane (LNG, LBG) is natural gas or biomethane that has been liquefied after processing.

Final quality and composition of biomethane depends on the operational parameters of the final use and on the upgrading technology used. Depending on the source, several trace components have to be closely controlled when using biomethane as a vehicle fuel, including: Siloxanes (risk of abrasion and increased probability for knocking), Hydrogen (risk of embrittlement for the metallic materials), Water (risk of corrosion and driveability problems), Hydrogen sulfide, H2S (corrosive in the presence of water could affect after-treatment devices, and combustion products could create problems by sticking the engine valves).

Trace components in biomethane can cause driveability problems

Siloxanes are one of the trace components in biomethane that can cause driveability problems. Siloxanes can cause abrasion and an increased probability for knocking.

Hydrogen is another trace component in biomethane that can cause driveability problems. Hydrogen can cause embrittlement for the metallic materials.

Water is a trace component in biomethane that can cause driveability problems. Water can cause corrosion and driveability problems.

Hydrogen sulfide, H2S, is a trace component in biomethane that can cause driveability problems. Hydrogen sulfide, H2S, is corrosive in the presence of water and can affect after-treatment devices. Combustion products can create problems by sticking the engine valves.

Methane has a better carbon intensity than diesel or gasoline

Methane-fuelled cars have lower energy consumption than gasoline-fuelled cars.

Methane emissions from NG-fuelled vehicles can be reduced by exhaust aftertreatment devices to low levels, but not necessarily for all engine concepts.

Methane has a high global warming potential (GWP over 100 years is 28 for methane).

Methane can be produced locally and therefore distribution is different from natural gas in many respects. Both bio-origin and fossil methane is used in compressed or liquefied state for storage and for transportation purposes. Compressed methane (CNG, CBG): natural gas or biomethane has been compressed after processing; mainly used for vehicles and typically compressed up to 200 bar. Liquefied methane (LNG, LBG): natural gas or biomethane has been liquefied after processing. Temperature is about -161.7 °C at atmospheric pressure and, when used as an automotive fuel, it can be stored in on-board cryogenic tanks (vacuum-isolated stainless-steel vessels), which have different operating pressure.

Methane can be stored in compressed or liquefied states

Natural gas or biomethane can be stored in compressed or liquefied states. Compressed methane (CNG, CBG) is natural gas or biomethane that has been compressed after processing and is mainly used for vehicles. It is typically compressed up to 200 bar. Liquefied methane (LNG, LBG) is natural gas or biomethane that has been liquefied after processing. Temperature is about -161.7 °C at atmospheric pressure and, when used as an automotive fuel, it can be stored in on-board cryogenic tanks (vacuum-isolated stainless-steel vessels), which have different operating pressures.

Frequently asked questions