“The green electricity needed to power every single vehicle would be three times less than that needed to fuel them with hydrogen”

Expert Interview – November 11, 2022

Johannes Buberger and his team from the UniBw M University in Munich (Universität der Bundeswehr München) have compared the carbon footprint of electric vehicles with that of cars fueled by diesel or gasoline. E-cars are the clear winner in terms of overall emissions.

Your publication shows a comparison of 790 modern passenger car variants, assessing and evaluating their CO2 balance across their entire life cycle. What is the difference to the studies conducted by Swedish Environmental Research Institute from 2017 and 2019, and what are the findings of your study?

The main difference is that in our study, we provided a broad market overview by investigating and comparing the vehicles currently available on the market covering many different combustion engines and power output sizes. The Swedish studies came to the conclusion that the “CO2 baggage” caused by battery production for electric vehicles has become less heavy in the last few years. Our study, on the other hand, has found that the overall emissions across the life cycle of a car are the crucial factor, and that they are much lower for electric vehicles. This means that the CO2 baggage can be “worked off” earlier.

Which carbon emissions are caused throughout the life cycle of a car?

You can break down the life cycle of a car into three phases, starting with production, which causes emissions during vehicle development and testing, the extraction of raw materials, processing and assembly, as well as transport and trade. The second phase is the period during which a vehicle is used by customers, with the respective fuel or power consumption being very good indicators for wheel-to-wheel emissions. Our study references WLTP data, a scientifically proven test method, enabling a fair comparison of the vehicles. Scrapping and recycling a vehicle is the third phase. The emissions caused at this stage can nowadays be offset against the emissions that can be saved when new vehicles are produced from the recycled materials. This equally applies to combustion engine vehicles and BEVs.

How did purely electric vehicles compare to vehicles fueled by gasoline or diesel, and how did hybrid vehicles fare?

Combustion engine cars fueled by gasoline have the worst carbon footprint because their consumption is relatively high. While diesel vehicles have a lower fuel consumption, they emit more CO2 per liter of diesel. Nevertheless, across its entire lifespan, a diesel combustion engine car creates around 20% less CO2 compared to a gasoline-fueled car. Battery electric vehicles have by far the best carbon footprint. This is not only true if they are powered by green electricity exclusively, but even when run on Germany’s standard energy mix. But our study also looked at and assessed the various types of hybrid cars, i.e. vehicles that use LPG, natural gas or hydrogen.

Is hydrogen the future when it comes to carbon emissions?

As things stand, hydrogen-powered vehicles have a worse carbon footprint because the available hydrogen is grey hydrogen produced from natural gas.

Would the carbon footprint of a hydrogen car compared to BEV look better if it were fueled by green hydrogen?

I don’t think so because green electricity also has a low carbon footprint and the losses during hydrogen production are considerable. The green electricity needed to power every single vehicle would be three times less than that needed if we used hydrogen.

Did the study also look at energy mix used during battery production in the manufacturing countries?

Yes, carbon emissions from battery production range from 60 to 100 kilograms of CO2 equivalent per produced kilowatt hour of lithium-ion batteries. Our assessment was based on the mean value of 80. That means we didn’t specifically take into consideration where a vehicle was produced but applied the mean value across the board.

So how sustainable are batteries?

The carbon footprint of batteries has been falling considerably, for example thanks to production in gigafactories powered by green electricity. But even in Asia, more and more production plants have been embracing sustainable energy sources. And the energy consumption of the production process itself has been dropping and is constantly being optimized.

What service life did you base your study on?

Our study was based on a vehicle service life 230,000 kilometers, a figure taken from the Kraftfahr-Bundesamt’s registration figures (Federal Motor Transport Authority – KBA). This assumes that a passenger car on average drives around 15,000 kilometers for 15 years before being scrapped.

But BEVs could last longer, couldn’t they?

Yes, as a matter of fact the battery warranties offered by vehicle manufacturers, cover 160,000 or 8 years on average. A combustion engine car on the other hand only comes with a 3-year warranty, maybe 12 for no-rust. Today, manufacturers such as Lexus issue blanket warranties for 1 million kilometers. A study by the Technical University of Munich has demonstrated that a service life of 160,000 kilometers is easily reached. A simulation using VW ID.3 cells resulted in a loss of capacity after 150,000 kilometers of less than 10%. If manufacturers guarantee a maximum loss of 30%, then that adds up to a mileage of 400,000 kilometers.

The calculations of your study were based on 230,000 kilometers. That would mean a battery could continue to be used even after the car itself has been scrapped. Does that mean that the manufacturer’s information is actually exceeded?

The warrantee period is a widely-discussed topic. Battery manufacturers have to make conservative estimates so that neither they nor the car manufacturer end up paying the price. For now, companies act on the side of caution when it comes to warranties.

Your publication’s vehicle usage data was based on WLTP figures. Are these calculations rather optimistic or rather pessimistic, or does it depend on the vehicle?

In general, WLTP figures for combustion engine vehicles tend to be on the optimistic side, regardless of how the vehicle is used. Generally speaking, consumption is higher in urban traffic than it is for long-distance driving, but driver behavior also plays a role. This applies to both combustion engine cars and BEVs. The faster you drive, the higher your consumption for both.

Let’s end by taking a look at batteries and current trends in this field: Will we ever be able to put range anxiety behind us?
Some people will always struggle with this, even if their anxiety is unfounded. We’re working our way towards a range of 500 kilometers. Add to that fast charging, and that’s more than enough for commuters.

This interview is an excerpt from an episode of The smarter E Podcast. You can listen to the full interview here

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