Electric vehicles – More or less sustainable than conventional vehicles?

Electric vehicles are usually presented to the mass population as the solution to decarbonise the transportation sector. However, are we really helping the environment by investing in such vehicles?

Controversial studies have been carried out showing that, in fact, the battery manufacturing of the EV plus the emissions produced during the lifetime of the vehicles lead to results in which EV would pollute more than conventional vehicles. This article seeks to present a discussion on the origin of those affirmations and why other studies are showing the exact opposite results. For the aim of simplification, everything will be linked to greenhouse gas emissions (grams of CO2 eq). Variables such as land use or materials obtention will remain out of scope for this analysis.

 

Where do the results of these studies come from?

One might think that the results of similar scientific studies should be, at least, similar. Then, it is hard to believe that there is science defending the electric vehicle whereas some studies are doubting their efficiency in GHG emissions abatement.

To understand the difference in the results, it is important to learn what are the LCA (Life Cycle Assessment) studies: These studies assess the environmental impact of a product or good by considering all the steps in the process of manufacturing of the product, its use and can include its disposal or recycling. It is the most “complete” environmental study that can be performed nowadays. The steps to carry out an LCA are the following:

  1. Goal and Scope definition
  2. Inventory Analysis
  3. Impact Assessment

As the first step shows, every time an LCA is performed, researchers will define the system boundaries, i.e. what inputs will be included in the study and what aspects will be excluded.

There is one particular environmental study popularly used for the transportation sector, the so-called well-to-wheel (WTW) analyses. According to the European Commission, these are the system boundaries in a WTW analysis:

Well-to-wheel analyses. Source: European Commission

As you might observe in this graph, the vehicle manufacturing would remain out of scope for this kind of analysis.

Now, imagine that there is a research group that would like to perform a comparison between electric and conventional vehicles. There are several factors that might highly affect the output of the study:

  • Is the study a WTW analysis? How is it including the “fuel” for the electric vehicles?
  • In case the study includes more elements than a WTW analysis, is the battery manufacturing included? What are the hypotheses considered for battery manufacturing calculations?
  • How many years is the battery thought to be useful for the vehicle?
  • Is the battery dismantling included in the study?
  • Which vehicles are being compared?
  • In which country and under which conditions are these vehicles compared?

All of these questions (and many more) might appear when performing an environmental analysis comparing several vehicles. Their responses will lead to different initial hypotheses, which at their turn will then lead to different results.

An example of what has been now exposed can be found in the following graph, which displays the result of different studies that were calculating the emissions yielded when manufacturing batteries (this is only one of the variables that could be included in a bigger study comparing EV to conventional vehicles):

Results obtained in several studies calculating the emissions produced in battery manufacturing. Source: Carbonbrief

As we can observe in the graph, one could affirm that manufacturing a battery emits 30kg Co2-eq/kWh capacity but also 330 kg Co2-eq/kWh. Choosing one or the other number could highly affect the results. If I was a politician, I could choose the number that would better support my political campaigns. If I was in favour of EV, I could take the lowest number!

Are the numbers wrong? Definitely not!

Each study considered different inputs and, therefore, different outputs were achieved. So, the new question would be, if every study shows a different result, how can we then calculate the sustainability in EV?

 

Understanding the results

As it was mentioned, each result considered different starting points. This means that the most generic affirmations are likely to be wrong. Some sentences like these ones should be avoided:

  • Electric vehicles are the key to abate GHG emissions.
  • Electric vehicles emit more than conventional vehicles.

Instead, affirmations like the following should be used:

  • Driving a Tesla Model 3 in Madrid will produce GHG savings compared to conventional vehicles.
  • Driving a Nissan Leaf in Beijing will produce higher GHG than driving a conventional vehicle.

An application of this way of thinking can be found in the following image:

Comparison between electric vehicles and conventional vehicles in the US. Source: CarbonBrief

In the image, we can see the comparison between two plug-in hybrid electric vehicles and one battery electric vehicle vs. a Mazda 3. As we can see in the image, there are some cases inside the US in which the electric vehicle emits more than the conventional vehicle, even if most of the time there is a small difference between them or the electric vehicle emits less.

How do I know if where I live I am more sustainable with an EV or a conventional vehicle?

There are two main variables that need to be taken into account:

  1. Where does electricity come from in your region?
  2. How is the battery of your electric vehicle manufactured?

 

Where does electricity come from?

You might check (even in real-time) the emissions of the electricity you are using in your region in sites like this one.

In Europe, countries like Norway, Iceland, Finland, France or Spain make it probable for your EV to become viable in terms of GHG emissions. Countries like Poland, some European islands, Germany or the Netherlands are more carbon-intensive electric systems.

Energy mix CO2 emissions heat map. Source: Electricitymap.org

How is the battery of your electric vehicle manufactured?

You don’t have to be aware of the way your car manufacturer is producing batteries, but here are some facts you might be interested in:

Tesla has built the so-called Gigafactory, which is the largest battery producer in the world, located in Nevada (US). Tesla’s Gigafactory is powered by renewable energies almost, which will lead to really low emissions during battery manufacturing. However, Nissan usually manufactures its batteries in Asia, which, in general, can entail around 20% higher emissions than batteries produced in the US. Therefore, a Nissan Leaf and a Tesla Model 3 will emit differently during their battery manufacturing.

 

Conclusion

Having reached this point, my personal recommendation would be: every time you read a controversial article, please verify other sources to obtain a more complete idea of the issue that is under discussion!

If you are planning on buying an electric vehicle and you want to be 100% sure on the GHG emissions abatement, try to find studies that are considering the region where you live or at least check the electricity mix of your country. And if you are planning on charging it at home, you can always contract your electricity with a 100% renewable energy retailer!

And also, take into account while deciding that during the coming years we will for sure experience an improvement in EV manufacturing, as well as a reduction in battery manufacturing emissions, which will create even a higher difference between EV and conventional vehicles. EVs have a higher room for improvement than conventional vehicles in terms of sustainability, so every year electric vehicles are more probable to become less pollutant than its internal combustion engine counterparties. 

 

Thank you for reading us and see you next month!

 

Author: Júlia Bayascas Caseras.

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