10 reasons why CNG is the new diesel

Diesel has long been the most economic fuel for fleets. It was also considered the most ecological liquid to combust until the truth about particulate matter and NOx emissions came out. OEMS have been cleaning up their act and have invested heavily to make their diesels comply with the stringent Euro 6d-temp emission standard, but it won't be tomorrow that the market has full faith in the "black fuel" again.

But if not diesel, then what? The answer could very well be compressed natural gas (CNG), especially for long-distance drivers, who will not be frowned upon when they pop into Hamburg's or any other big city's low-emission zone if their car carries a g-tron, TGI or G-Tec badge. Here's 10 reasons to go for gas.

1. Low fuel price. A kilo of CNG is 30 to 50% cheaper than a litre of diesel. The fuel consumption is roughly the same for both: between 4 and 6 units per 100 km, meaning that the fuel bill is equally reduced by 30 to 50%. 
2. Better for long distances than hybrids. Once a hybrid's battery is depleted - which happens after maximum 50km unless you have a new BMW X5 45e or Mercedes GLE 350de - the combustion engine has to work extra hard because of the added weight, resulting in a less than favourable fuel consumption. Not so with CNG: the average car can drive 300 to 400 km on natural gas and then between 70 and 150 km on petrol.
3. Very low NOx and PM emissions. Compared to diesel and even to petrol, natural gas creates far less nitrogen oxides (NOx) and particulate matter (PM) when combusted. The combustion process is also quieter. CNG is therefore a better 'urban' fuel than diesel.
4. Lower CO₂ emissions, both tailpipe and well-to-wheel. Cars that run on natural gas emit about 30% less CO₂ than their peers burning petrol and are more or less on a par with diesel. Looking at things from well-to-wheel, CNG wins from other fossil fuels hands down.
5. CNG is plentiful. The Earth’s natural gas reserves are huge, guaranteeing supply for decades to come. Also, natural gas prices do not depend on those of oil. They are less subject to fluctuation and have remained pretty stable over the past years.
6. CNG can be sustainable. It is possible to create methane – CNG’s main component – from biological waste and sludge. Audi even creates it by splitting water into oxygen and hydrogen, which is combined with CO₂, making it carbon neutral.
7. Less expensive than hybrids. A CNG car typically costs €1,500 more than the petrol model it is derived from. And the model offer is expanding: Audi, Fiat, Iveco, Mercedes, Opel, SEAT, Skoda and VW all have at least one CNG derivative on offer.
8. Expanding infrastructure. A major obstacle to the success of CNG cars is starting to crumble as more petrol stations offer CNG. From 860 today, Germany will have 2,000 natural gas stations in 2025. The tiny Belgium already has 100 stations.
9. CNG cars can park underground. Contrary to LPG powered vehicles, CNG vehicles are not banned from underground car parks. LPG is heavier than air and can spread over the car park’s floor, creating a risk. That is not the case with CNG, which is volatile.
10. CNG is safe. The gas tanks are subject to very strict safety protocols and are made of very strong materials such as carbon fibre reinforced plastic (CRFP). They can resist 750 bar of pressure, extreme heat and crash impacts. The tanks also have safety valves.

So should you replace diesel by CNG in your fleet? Read our analysis here.

Picture copyright: Audi, 2018