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More or less lithium in our vehicles?

February 14, 2020
Lithium Batteries

Today’s EV market race is about having the biggest autonomy possible to reassure us, the consumers, responding to our main question: how many kilometers can we drive on a single charge? If we care about being eco-responsible though, shouldn’t the question rather be:

How many kilometers do I need for my daily use?

EVs are not intrinsically low-footprint solutions. What makes a difference in their carbon footprint is the energy sources of electricity production, the energy consumption, and the battery size.

Considering these elements, we decided to launch a mobility study to figure out with our community the autonomy and battery size of the active, low-footprint vehicle we develop.

The carbon footprint of EVs

Electric vehicles (EVs) have several benefits. They help keep a good quality of air in cities, reduce sound pollution, and they are more efficient than internal combustion engine vehicles (ICEV).

However, EVs are not intrinsically better for the environment.

The environmental impact of a vehicle can be measured by using its life-cycle emissions. This metric considers the CO2 and other greenhouse gas emissions produced during the vehicle’s production, its use (we use 180 000 km as a reference here), and its recycling. Lifecycle emissions are usually expressed in tons of CO2 equivalent (tCO2-eq) or simply tons of CO2 (tCO2).

The potential of EVs to be low-emission solutions depends mainly on three factors mentioned hereinabove:

  1. The sources of energy used to produce the electricity they are powered with;
  2. Their energy consumption;
  3. Their production: An EV can have 30 to 90% higher production emissions than an ICEV of equivalent size, mainly due to its battery (Ellingsen et al. 2016).

Let’s look at the effect of these three factors.

Energy sources

The sources of energy used to fuel an EV can determine if an EV’s total emissions will be higher or lower than those of an ICEV.

The emissions of coal-produced electricity are actually higher than those of petrol or diesel. Thus, powering an EV from coal-produced electricity during its life results in higher emissions than using ICEV of equivalent size.

The life-cycle emissions of electricity generation range from 21 gCO2 per kWh for the wind energy to 1029 gCO2 per kWh for coal. The European electricity mix average is somewhere halfway these two at 521 gCO2 per kWh (Ellingsen et al. 2016). The image below illustrates the effect of these energy sources on the life-cycle emissions of EVs.

CO2 emissions by vehicle types
Powering an EV from coal-produced electricity results in a higher footprint than using an equivalent size ICEV that is fueled with petrol or diesel (Source: European Environment Agency)

Energy consumption

The energy consumption of a vehicle is directly affected by its weight. A heavier vehicle produces more emissions per kilometer than a lighter one as it requires more energy to move. In fact, the weight of an EV correlates to its energy consumption by a factor of 5.6 kWh/km per 100 kg (Ellingsen et al. 2016).

The energy consumption of a luxury EV that weighs 2100 kg (20.7 kWh/100km) is 42% higher than the energy consumption of a small EV that weighs 1100 kg (14.6 kWh/100km). This difference is directly reflected in their use phase emissions, where the luxury EV produces 42% more emissions than the small EV.

CO2 emissions by vehicle weights
A heavier vehicle produces more emissions per kilometer as they need more energy to move than a lighter vehicle (Source: CIXI)

The energy consumption is also directly affected by the energy efficiency of the propulsion system of the vehicle (EVs vs. ICEVs). EVs have tank-to-wheel (TTW) efficiencies ranging from 1.4 to 6.7 times higher than those of an ICEV.

Tank to Wheel efficiency
EVs produce fewer emissions than an equivalent size ICEV thanks to their higher tank-to-wheel efficiency and cleaner energy sources of electricity. (Source: CIXI)

When we compare a small EV to its equivalent-size ICEV, the EV produces 61% less emission than its ICEV counterpart. Similarly, a luxury EV produces 90% less emissions than its ICEV counterpart (considering Europan electricity mix). This is partly due to the cleaner energy sources, and greatly due to their higher tank-to-wheel efficiencies. These efficiencies allow EVs to have consumptions of 1.6 Le/100km for the small EV, and 2.3Le/100km for the luxury EV (with a conversion factor of 8.9 kWh per liter of gasoline. Source: Natural Resources Canada).

Use phase life cycle emissions
EVs produce fewer emissions than an equivalent size ICEV thanks to their higher tank-to-wheel efficiency and cleaner energy sources of electricity. (Source: CIXI)

Battery size

The size of the battery plays an important role in the footprint of an EV. It contributes 14% to 26% of the EV’s total life-cycle emissions.

The largest contribution of the battery to the footprint of an EV comes from its production, adding about between 0.5 to 5 tons of CO2 per 10 kWh (Hall et Lutsey 2018). This represents 33% to 46% of the total production phase emissions and puts EVs at a high initial environmental debt compared to ICEVs.

For the use and recycling phases, the battery contributes 4% to 11% and 14% to 23% of the phase emissions, respectively, depending on the vehicle and battery size.

Complete life cycle emissions
The battery contributes to 33% to 46% to the production phase, 4% to 11% to the use phase, and 14% to 23% to the recycling phase. The overall battery contribution represents 14% to 26% of the total lifecycle emissions of an EV. (Source: CIXI)

Beyond CO2

Electric batteries have other environmental impacts, aside from contributing to the carbon footprint of EVs. For example, 75% of the Lithium reserves are located in the water-scarce regions of Bolivia, Chile, and Argentina. The water-intensive extraction of Lithium puts extra pressure on water resources, introduces risks of water, soil, and air contamination, and destroys the local landscape (Hollender et Shultz 2010).

The most popular battery used by EV manufacturers is the Lithium Nickel Manganese Cobalt Oxide (NMC) because of its competitive energy density. This battery is 6% made of Cobalt. Cobalt is a toxic metal and it is extracted in an unregulated artisanal manner in poor and politically unstable Republic of Congo, who has 50 to 60% of the world resources (Mann 2017).

Considering the environmental costs of the three factors discussed (sources of energy, energy consumption, and vehicle production), as a hyfit manufacturer we ask ourselves the question:

How much lithium should we have in the vehicle we develop?

We decided to answer this question in the following way.

The hyfit vehicle

At CIXI we are building the hyfit, a new type of active and low-footprint vehicle that (re)introduces daily physical activity in our lives. We believe daily physical activity brings more than improved health. We also believe that people are ready to adopt new and lower environmental impact solutions.

In the spirit of creating a low-footprint vehicle, we are currently carrying out a study to better understand people’s daily mobility needs. The idea behind this study is to find out how big of a battery we should put in the hyfit to satisfy our pilots, without necessarily joining the market race of bigger-is-better.

This study consists on collecting and analyzing GPX files of a large sample of people that record their trips for one week. GPX files contain GPS information or their position over time. From these files, we can extract speed, acceleration, and elevation throughout a trip. With a simple model of a vehicle, we can then compute the energy consumption over the recorded trip.

This information allows us to do two things.

Firstly, it helps us understand the mobility needs of individuals: their autonomy, type of roads taken, type of trips, number of people. Considering this, we can better understand the battery size that would best satisfy people.

Secondly, we thank participants by preparing them a personalized report containing their energy consumption and environmental footprint in grams of CO2. This helps us and participants better understand the environmental impacts of their mobility. To give a little CIXI touch to this report, we also share the potential extra time people would have for exercising and developing a healthier lifestyle.

How the experiment takes place

People of our community that join the study install a GPX file-generating application in their mobile device. Then they are asked to record their trip every time they take their car during one week. At the end of each trip, participants rename the generated file and send it to us.

It is an effort to add these extra steps to their normal commuting, and naturally, people forget to record their trips the first day (we have already experienced it ourselves). Instead of coding a whole complex app, or making things more complicated we quickly tested with a small piece of paper that participants stick in their cars to help them not forget about the study.

Trips card
Trips card to remember the study for a week. (Source: CIXI)

Today, we are still in the data gathering process for our mobility study. If you want to know your environmental footprint while shaping an environmentally conscious choice on the next active EV, we invite you to join the CIXI community. You will be able to participate in our mobility study, get invited to test drives of prototypes, and shape the future of active, low-footprint transportation.

À bientôt,

References

  1. H. C. Righolt and F. G. Rieck, “Energy chain and efficiency in urban traffic for ICE and EV”, 2013 World Electric Vehicle Symposium and Exhibition (EVS27), Barcelona, 2013, pp. 1–7. doi: 10.1109/EVS.2013.6914820
  2. Linda Ager-Wick Ellingsen et al, “The size and range effect: lifecycle greenhouse gas emissions of electric vehicles,” 2016 Environ. Res. Lett. 11 054010. doi:10.1088/1748–9326/11/5/054010
  3. European Environment Agency. “Infographic: Range of life-cycle CO2 emissions for different vehicle and fuel types” Prod-ID: INF-66-en, Published 29 Aug 2017 Last modified 22 Nov 2017. Ragan’s PR Daily
  4. Hall et N. Lutsey, “Effects of battery manufacturing on electric vehicle life-cycle greenhouse gas emissions”, Thr international council on clean transportation — ICCT. Beijing, Berlin, Brussels, San Francisco, Washington, 2018, pp. 1–12.
  5. R. Hollender and J. Shultz, “Bolivia and its Lithium: Can the ‘Gold of the 21st Century’ Lift a Nation out of Poverty?” A Democracy Center Report, Cochabamba, 2010. pp. 1–57.
  6. E. Mann, “Digital Technology is Dependent on Forced Labor: The Exploitative Labor Practices of Cobalt Extraction in the Democratic Republic of Congo”, 2010.
About the author
Nina Omerovic-Beccalli

CIXI Team