iPoint Blog
Carbon Footprint of e-mobility strongly depends on the energy mix

Is e-mobility a truly sustainable solution?

E-mobility is a hotly debated issue right now, both in scientific circles and in the media. Some herald it as enabling mobility with fewer carbon emissions, while others claim battery production makes electric vehicles (EVs) just as ‘dirty’ as cars with internal combustion engines (ICE). These opposing positions can lead to a high level of uncertainty, both for consumers and for policy makers. As is so often the case, the verdict is a stout “it depends”, so it’s worth taking a closer look at the life cycle of electric cars.

A life cycle perspective for transparency issues

On June 26, 2019, ifu Hamburg, Member of iPoint Group, held their Life Cycle Workshop at the Stadthalle Reutlingen. The event brought together more than 50 life cycle enthusiasts from the fields of industry, research, and consulting to exchange their experience and knowledge about topics concerning Life Cycle Assessments.

This year, the workshop was part of the fw:transparency event, a joint event by ifu und its parent company iPoint, which focused on business transparency in the context of sustainability and compliance. Consequently, the Life Cycle Workshop’s main focus was “Transparency requires a life cycle perspective”.

The difficulty of assessing the e-mobility carbon footprint

Kirsten Biemann presenting about e-mobility at the Life Cycle Workshop
Dr.-Ing. Biemann presenting about e-mobility at the Life Cycle Workshop

Dr.-Ing. Kirsten Biemann from the ifeu Institut für Energie und Umweltforschung Heidelberg has been working with Life Cycle Assessments for nearly 10 years and earned a doctorate in the field of comparative LCAs in 2014. She has been a Research Associate at ifeu since 2015 and now focuses on analysis of the environmental impact of the various modes of transportation along the entire process chain.

At the Life Cycle Workshop 2019, she explained that, when ifeu performed a meta study of the climate impact of EVs, they discovered findings that ranged from 50 to 210 g of CO2 per km driven. Biemann reported that the huge gap is due to a variety of factors, primarily lifetime mileage of a vehicle, the type of driving (short or long range), the fuel mix used for charging the car during its use phase, and the impact of battery production.

Factors influencing the carbon footprint of EVs

ifeu then created its own model, based on a generic, mid-sized electric car. The study focused on the vehicle’s overall carbon footprint and the resulting climate impact over its entire life cycle. Modeling was done with the Umberto software developed by ifu, using the ecoinvent data base. The following results are all based on the Umberto model seen below:

Carbon footprint model for a generic e-car created with the software Umberto
Excerpt of a carbon footprint model for a generic e-car created with the software Umberto

Calculating the energy mix correctly is key so, assuming an average use phase of 10-12 years, the model also took projected future changes into account. Currently, the energy mix in Germany still includes a high percentage of fossil fuels; but during the time the car will be on the road, it is expected to move toward much more renewable energy, and thus a considerably smaller carbon footprint.

Another important factor is the vehicle’s overall lifetime mileage, which can vary greatly. So rather than simply arriving at a fixed number for CO2/kwh used, ifeu decided to pinpoint break-even points as identified by their comparative carbon footprint analysis.

Carbon footprint of e-cars
Carbon footprint of e-cars compared to ICE powered cars under consideration of the energy mix (Source: Agora Verkehrswende (2019): Klimabilanz von Elektroautos.)

Generally, the initial energy input during the manufacturing phase is about the same for both electric and conventionally powered cars. But EVs add another large energy chunk to their ecological impact in the form of battery production. So, it’s only during the use phase that e-vehicles really shine: their CO2 impact is a lot smaller than that of ICE powered cars and the relative CO2 savings increase the longer the car is on the road.

Which brings us back to the break-even point. In this mid-sized car scenario, it occurs between 60 – 80,000 km, well within a car’s typical lifespan.

Fine-tuning results by changing modeling parameters

By adjusting some of the variables in their model, ifeu was able to show just where the critical points are to make e-mobility more sustainable. In a scenario called “City”, the analysis was based on the fact that electric cars are often the second vehicle in a household and therefore mainly used in city traffic for short range driving. Based on that, the model assumes a smaller, low-range battery and also lower lifetime mileage.

The result is a break-even point that is reached much sooner, at around 40,000 km. So, despite the higher up-front carbon input during the production phase, the biggest reduction of climate impact with electric vehicles remains during their use phase. Which makes the energy mix used to power them a key issue!

The dirty little secret of battery production

The critically important factor in the life cycle of an EV is still its battery. Nearly 50% of the battery’s overall CO2 impact is generated during its manufacturing phase, due to the high energy input required. So, the energy mix used is a crucial variable.

Currently, EV batteries are mainly produced in the US, China, Japan, and Korea – all of which still have high rates of fossil fuels in their energy mix. A switch to using more renewable energy during battery production could thus significantly lower the overall carbon footprint of the vehicle.

CO2 balance of the e-car battery
Power consumption and energy mix in cell production dominate the CO2 balance of the battery (Source: Agora Verkehrswende (2019): Klimabilanz von Elektroautos.)

You can read more about the role of batteries in e-mobility in our blog article on LCA of lithium-ion batteries.

Assuming that cell production continues its dynamic advancement – using fewer raw materials and less energy while achieving higher efficiency – the break-even point of a 35 kWh battery could be reached as early as 30,000 km, or 50,000 km for a longer range, 60 kWh battery.

Future outlook: more sustainable e-mobility by 2030

So, how can we improve the LCA numbers for e-vehicles by 2030 and achieve a lower carbon footprint?

  • Decarbonize the energy mix both in manufacturing and use
  • Increase engine efficiency
  • Lower charging losses
  • Keep battery capacities as small as possible while still achieving consumer acceptance
  • Improve the efficiency of battery production

These suggested improvements could cut the carbon footprint for battery production in half compared with today. In addition, higher lifetime mileage also has a positive impact. In combination, these improvements could make the transition to a truly sustainable e-mobility feasible.

Improvements in e-car cell production by 2030
Expected improvement in GHG emissions from battery cell production by 2030 compared to today (Source: Agora Verkehrswende (2019): Klimabilanz von Elektroautos.)

The complete ifeu study is available only in German, but you can find the Executive Summary in English at: https://www.agora-verkehrswende.de/en/publications/lifecycle-analysis-of-electric-vehicles-study-in-german-with-english-executive-summary/

 

Presentations and videos of the Life Cycle Workshop are available at: https://www.ifu.com/en/events/life-cycle-workshop/

The next Life Cycle Workshop will take place in 2021. To receive an invitation for the next workshop ► Subscribe to our newsletter

ifu Hamburg

1 comment

  • I am wondering what would be the realistic implication of the fact, that e-cars may last much longer than combustion engine cars.
    Just think about the idea/goal of E. Musk to build cars and batteries to last a million miles.