What is the least practical vehicle

Which vehicle drive generates the least CO2?

Hybrid, electric car, fuel cell or classic combustion engine? Young researchers have investigated which drive technology is the most climate and environmentally friendly in a practical test. The result: In terms of consumption and CO2 emissions, the plug-in hybrids have the lead with today's electricity mix, followed by the electric car. The fuel cell drive, on the other hand, can only show its advantages if the hydrogen is generated from renewable sources.

It seems clear: In car traffic, alternative drives to the classic combustion engines are needed. Because diesel and gasoline engines produce fine dust, nitrogen oxides and the greenhouse gas carbon dioxide. If the air in cities is to get better and climate protection to move forward, more environmentally friendly drive technologies are therefore necessary. There are already models with electric drives and various hybrid solutions, and hydrogen vehicles already exist. But which are the most environmentally friendly?

Five vehicle drives in the test

Vehicle technology students at Esslingen University have now examined this in a practical test. They wanted to know: How do five vehicles with five different drives perform in a practical everyday test? What do they consume in the city, on the motorway and when driving overland? How much climate-damaging CO2 do you emit in the process? To answer these questions, the young researchers first selected five test vehicles of similar size: mid-range vehicles with a diesel engine, a gasoline engine, an electric vehicle with a battery drive, a prototype with a fuel cell and an author with a plug-in hybrid drive.

For their test, the young researchers chose a 68-kilometer circuit north-west of Stuttgart - around the city of Leonberg - as a real model. In this route, city trips as well as country roads and motorway sections were represented. The students then transferred the characteristics of this route to the roller dynamometer in the university's laboratory and tested the five vehicles there. The consumption, converted uniformly into kilowatt hours, and the CO2 emissions were compared. For the electric vehicles, the researchers used today's electricity mix as a basis.

Hybrid is ahead

The result: "In practice, the plug-in hybrid car does by far the best thanks to the combination of a classic gasoline engine and an electric drive," explains study leader Werner Klement. On average, the hybrid vehicle emitted the least amount of CO2 and had the least impact on the environment. "The result is almost unbeatable," said Klement. The vehicle with the purely electric drive, on the other hand, was only superior to the hybrid model in phases: In operating states with a lot of energy recovery (recuperation), there was an advantage over the hybrid vehicle - however, the CO2 pollution from battery production was not taken into account.

As expected, the vehicles with classic combustion engines performed worst. In terms of consumption and CO2 emissions, the diesel and gasoline vehicles were almost on par in real operation. According to the researchers, the differences are negligible. The vehicle with the fuel cell performed better. In terms of consumption, it was clearly superior to gasoline and diesel cars. However, when it comes to CO2 pollution, such a drive is only ahead if the hydrogen is generated from renewable sources. With the current electricity mix, the CO2 pollution would be greater than with conventional drives, as the young researchers report.

Source: Esslingen University of Applied Sciences

December 28, 2018

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