Electric, fuel cell or diesel?

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Are electric cars environmentally friendly? And what about fuel cell cars? Questions that have been hotly debated in the Golem.de forum lately. In a study, the Fraunhofer Institute for Solar Energy Systems ISE compared the two vehicle types with each other and with a diesel car.

The Freiburg researchers investigated the emissions of greenhouse gases that occur over the entire operating cycle of a vehicle, i.e. during production, operation and finally disposal. The study looked at a fuel cell vehicle with a 95 kilowatt drive and a 5.6 kilogram tank with a range of around 500 kilometers, two electric cars – one with a 90 kilowatt hour battery (kWh) and a range of 400 km, the other with a 60 kWh battery and a range of over 300 km – and a diesel vehicle.

For the fuel cell cars, the researchers used natural gas steam reforming as the worst way to obtain hydrogen, electrolysis with wind power as the best method, and a mix of half the two methods. In the case of electricity, they assumed solar power from a photovoltaic system to be the best option and the current German electricity mix to be the worst. The mileage in each case was 150,000 km.

It had been shown that for the period from 2020 to 2030 the emissions of a fuel cell car, even if it is operated exclusively with hydrogen from the natural gas reforming process, are lower than those of an electric car with a 90 kWh battery, which is charged with electricity according to the current mix. Compared to a car with a 60 kWh battery, they are slightly higher at 150,000 km.

If the electric cars are charged with solar power, they perform better than the fuel cell car if it is operated with the hydrogen mix. However, the fuel cell car emits the fewest greenhouse gases if it is filled exclusively with so-called green hydrogen.

The electricity mix changes

For the following decade, the ranking will change: electric cars charged with electricity from the socket will perform better than fuel cell cars powered by so-called black hydrogen. This is due not only to improved batteries but also to a changed electricity mix. Improvements in technology reduce overall emissions. The car with the 60-kWh battery, which is charged exclusively with solar power, performs best, closely followed by the fuel cell car, which is powered by green hydrogen.

The diesel vehicle, on the other hand, is better than its competitors in terms of production. However, its emissions mean that it is losing this lead again. With a mileage of 150,000 km, only the electric car with the large battery is slightly worse. But after just a few thousand kilometres, the diesel engine is already the leader in terms of emissions.

“The study also shows that battery and fuel cell vehicles complement each other ideally. Fuel cell vehicles are more climate-friendly for long ranges and battery vehicles for short ranges,” said Christopher Hebling, Head of Hydrogen Technologies at Fraunhofer ISE. However, the researchers limit that the study did not take into account a number of points, including Second Life for batteries, the effects of synthetic diesel fuels or the effects of land and water consumption.

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Mette Frederiksen is a The Washington Newsday correspondent. With her coverage of general science, NASA and the interface between technology and society, Frederiksen has been in the Science Desk's Technology Beat since joining Washington Newsday in 2018.

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