Compressed natural gas – or CNG for short – is increasingly being mentioned as an alternative to conventional fuels. It most commonly takes the form of natural gas, a naturally clean fuel.
It is used in millions of households to provide heating and hot water, as well as for cooking. CNG is an equally suitable everyday source of energy in the world of mobility. It is already used by almost 100,000 cars on Germany’s roads – cars that produce significantly fewer emissions than their diesel and gasoline-driven brethren with no loss of driving performance. This is because CNG burns more cleanly than gasoline and diesel, releasing practically no particulate matter in the combustion process.
Since it also has a high energy density, users benefit in terms of price too: the cost of running a car on CNG is around half that of a gasoline-driven vehicle and just over two-thirds of that of a diesel. The lower energy tax, recently extended until 2026, boosts the price advantage further, while reduced CO2 emissions also result in lower vehicle tax.
A sustainable source of energy, CNG benefits from tax concessions, as do the vehicles that run on it. Not only is it a low-cost alternative to conventional fuels, but it is also particularly future-proof, containing an ever-increasing percentage of CO2-neutral biogas from renewable resources.
Moreover, it can also be mixed with hydrogen generated in a climate-neutral process and in unlimited quantities using energy from renewable sources. Here, methane is extracted from plant residues, or even from manure, and then fermented in biogas plants to produce CNG, which is fed into the gas distribution system spanning some 500,000 kilometers.
Power-to-gas technology, which likewise enables climate-neutral energy production, is now also available. This involves generating hydrogen from renewable energy – that is, from wind or solar power – via electrolysis. Hydrogen can be fed directly into the gas distribution system in a similar manner to biogas. However, since the hydrogen admixture may not exceed five percent, hydrogen is “methanized” in a second step: it is combined with carbon dioxide to produce “synthetic natural gas” that can be fed into the gas distribution system in unlimited quantities.
The Volkswagen Group has joined forces with industry partners from the fields of energy production and supply as well as filling stations with the objective of increasing the number of CNG cars tenfold and doubling the network of filling stations to around 2,000 by 2025.
Audi is currently demonstrating the practical viability of this power-to-gas technology. The company has been operating a power-to-gas plant in Werlte, Lower Saxony, since 2013, producing enough synthetic natural gas every year to enable 1,500 CNG vehicles to cover 15,000 kilometers apiece in climate-neutral fashion.
Dr. Jens Andersen is in charge of Volkswagen’s natural gas activities and can quote several interesting comparative figures. For instance, a Golf running on natural gas emits just 103 grams of CO2 per kilometer. This figure falls to 24 grams of CO2 if the tank is filled with biogas from renewable energy sources, and to just 15 grams of CO2 per kilometer in the case of synthetic natural gas.
CNG is a readily available alternative to conventional fuels that is also sustainable, low-cost, future-proof and suitable for daily use. In terms of everyday driving, there is no difference between CNG cars and their diesel and gasoline-driven brethren when it comes to driving pleasure, comfort and agility.
The Volkswagen Group currently offers 14 passenger car models and a light commercial vehicle – ranging from the VW eco up!, SKODA Citigo G-Tec and SEAT Mii Ecofuel for outstandingly economical urban mobility all the way to premium Audi models. The offering also encompasses the ultra-modern and efficient natural gas vehicles manufactured by Volkswagen Truck & Bus, including the MAN and Scania brands, among others.