CNG – the cost-effective alternative

CNG – the cost-effective alternative

Drivers of a CNG vehicle will be pleased when they fill up. Depending on the particular vehicle model, less than four euros are frequently sufficient to travel a distance of 100 kilometres (see chart). By comparison with conventional fuels, CNG is therefore a particularly cost-effective alternative. Drivers filling up with CNG are able to save virtually half the fuel costs by comparison with petrol, and nearly one third compared with diesel.

However, this cost benefit is not visible at first glance. At filling stations, the price of CNG is given in kilograms. For years, stakeholder groups and experts have been asking for the supply of CNG to be calculated in litres as is usual for petrol and diesel. Any initiatives directed towards the use of a uniform measurement unit have so far failed due to complicated conversion formulas, the German Calibration Law – and the laws of physics. CNG is stored in the distribution grid and at filling stations in compressed form and it is pumped into vehicle tanks at a pressure of 200 bar. The gas expands at lower pressures. Theoretically, the volume could therefore increase if the compression intensity were lower without the energy content increasing. Conformity with the German Calibration Law requires that the volume of CNG must therefore be given in kilograms because the weight always remains constant irrespective of the level of compression.

Ultimately, what customers want to know is the amount of energy they receive in their tank. In order to determine the overall cost benefit of CNG, it is therefore necessary for the energy content to be taken into account so that a comparison can be made with petrol or diesel. The energy content of one kilogram of CNG corresponds approximately to that of 1.5 litres of premium petrol or 1.3 litres of diesel fuel. Or put differently: a kilogram of CNG has an energy content that is almost 50 percent higher than a litre of petrol – 13.3 kilowatt hours (kWh) compared with 8.6 kWh. A litre of diesel has an energy content of 9.9 kWh.

The reduced energy tax rate also contributes to the price advantage of CNG at the filling station. The intention of the federal government is for this rate to promote the increased use of this fuel. In May 2017, the federal government extended the tax reduction for CNG – originally limited until 2018 – until the year 2026 on account of the considerable and potentially still growing contribution of CNG to reducing CO2 emissions.

Alongside more favourable fuel costs, the motor vehicle tax statement also favours a CNG model. When calculating motor vehicle tax, the CO2 emissions are also taken into account alongside the displacement of the engine. And since vehicles with a CNG power unit consistently have a particularly favourable CO2 footprint, the motor vehicle tax rate is also lower. For example, the tax authority only calculates 34 euros each year for a VW Golf Variant TGI BlueMotion 1.4 (instead of 46 euros for the comparable petrol model), while a ŠKODA OCTAVIA G-TEC Combi pays 36 euros (instead of 64 euros).

In addition, environmentally aware drivers already benefit financially when they purchase a CNG vehicle. Depending on the place of residence, numerous regional gas utilities support the purchase decision with a bonus of up to 1000 euros.

3.39 euros instead of 6.32 euros for fuel costs required to drive 100 kilometres.

As an example, anybody who drives a Golf Variant TGI BlueMotion 1.4 will pay only 3.39 euros per 100 kilometres at a CNG price of 0.96 per litre and with consumption of 3.6 kilos. Meanwhile, the owner of a comparable petrol car pays 6.32 euros for fuel costs (at 1.29 euros per litre).