What diesel cars

Emissions scandal and driving bans Pros and cons of diesel engines

The Federal Administrative Court in Leipzig is negotiating possible driving bans for diesel vehicles. For a long time, diesel engines were considered to be the better combustion engines, but this reputation has suffered greatly when exhaust gas manipulation became known, for example from Volkswagen. What are the advantages and disadvantages of diesel technology?

Advantages of diesel engines

Diesel engines are economical: They burn much better than Otto engines. "An energy yield that is up to 15 percent better, sometimes more, is possible compared to the Otto engine," says Professor Klaus Augsburg, Head of Automotive Technology at the Technical University of Ilmenau. Some even speak of 20 percent more efficiency. "That means the lowest consumption and unmatchable in relation to other internal combustion engines," says the expert. The diesel achieves almost 40 percent efficiency. The gasoline engine barely more than 20. This has further advantages.

Low CO2 emissions: Due to the low consumption, the CO2 emissions are also significantly lower than with the gasoline engine. "The CO2 issue has been important for many years. That is why the diesel engine has become widespread," says Augsburg. Around a third of the cars in Germany run on diesel. It is still unbeatable in the heavy haulage sector. 96 percent of trucks drive diesel. However, this is less due to the CO2 emissions than to the power.

Diesel engines are powerful: Due to the higher efficiency, the motor has more power and it lasts longer. Truck engines cover well over 1 million kilometers. Some even two million. Cars also crack the 500,000 kilometer limit, while the gasoline engine runs out beforehand.

Despite the advantages, the diesel boom in the passenger car sector is over. Last year, only 38 percent of the new registrations were diesel engines. That is a decrease of ten percent. The reason are:

Disadvantages of diesel

Diesel engines pollute the environment: Klaus Augsburg believes diesel engines could be much cleaner. Particle filters are so good today that they can filter fine dust 100 percent. But that costs money. "In this respect, a diesel engine is always expensive."

Particulate matter from diesel engines is harmful to health: Particulate matter from the diesel should be so small that it can penetrate the cells and cause cancer there. In addition, lung and cardiovascular diseases.

Diesel engines have high nitrogen oxide emissions: The gas causes acid rain, smog and accelerates global warming. It is said to be produced in larger quantities in diesel than in petrol. The reason: Diesel engines burn very efficiently with a high degree of efficiency. This creates temperatures of up to 2,500 degrees, which means that nitrogen oxidizes to nitric oxide.

So if I want to make the engine nitric oxide-free, I have to make it more inefficient. In addition, I have to switch on some filters afterwards and they are expensive and that is why there was the problem with the emissions scandal.

Prof. Klaus Augsburg, TU Ilmenau

Summary: Diesel engines are economical, have a long service life, produce less CO2 than gasoline engines, have more power than gasoline engines, but are harmful to health and bad for the climate.

With money you can eliminate the disadvantages, the technology is there. Ultimately, the diesel will be around for a long time because there are no more environmentally friendly alternatives, Klaus Augsburg assesses the situation.

However, if you compare the combustion engine with modern technology, for example with a motor that is supplied with electricity via a fuel cell, it would be out of the running immediately. "If I look at the environmental balance, then a fuel cell operated with hydrogen is already in the direction of non plus ultra," says Augsburg.