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2019.11.05 09:00

Lithuanian researchers show diesel cars to be less polluting than petrol-fueled vehicles

LRT.lt 2019.11.05 09:00

New diesel-powered passenger vehicles are not only more fuel efficient, but also emit less CO2 than similar vehicles with petrol engines, a Lithuanian study suggests.

Researchers of the Faculty of Transport Engineering at Vilnius Gediminas Technical University (VGTU) conducted emission tests on cars with petrol and diesel engines made in 2019, according to a VGTU press release.

Measurements were taken at three different speeds: 50 km/h, 90 km/h and 120 km/h. In addition, the engine load was increased during the tests, taking into account that, in reality, cars accelerate during overtakes, uphill drives or on bends.

The results show that diesel engines need 26 percent less fuel and emits 16 percent less CO2 compared with petrol engine cars. Emission of other pollutants was insignificant due to the effective functioning of emission control systems in the tested cars.

In general, both types of engine meet the latest EURO 6 standard.

“After testing the engines at three different speeds, we have found that the actual CO2 emission is similar to the one declared by the manufacturing company. Also, we have estimated that emissions of a diesel engine are 15-20 percent smaller than those of a petrol engine,” says VGTU Associate Professor Alfredas Rimkus. “The tested cars have systems that reduce emissions, so emissions of other pollutants – carbon monoxide, hydrocarbons, nitrogen oxides – are very close to zero.”

One of the main reasons for lower CO2 emissions is that diesel engines of new passenger vehicles are more efficient, that is, they use less fuel.

Rimkus notes, however, that pollution parameters of both types of car engines depend on age and installed technologies: particulate filters, catalytic converters.

“We have tested new passenger vehicles and these usually do not have particulate emissions. Typically, particulate and nitrogen oxide emissions are higher in older diesel cars where emission control systems are not renewed or poorly maintained,” says Rimkus.

The type of fuel that is used is also relevant, he adds. New generation biodiesel, manufactured with latest technologies, contains less carbon, which is replaced with hydrogen. Therefore, CO2 emissions can also be reduced by choosing more environmentally-friendly types of fuel.