The right when & how enables low-CO2 electric car charging

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The right when & how enables low-CO2 electric car charging-charging

The number of registrations of electric cars is increasing significantly, and there is still a controversial debate about how environmentally and climate-friendly these cars really are. For a holistic view, you not only have to consider how much energy is used in the manufacture of the vehicle and what emissions are produced, but also how much emissions are used to generate the electricity with which the vehicle is charged.

One thing is clear: the more renewable energy flows into the batteries, the better the ecological footprint of the e-car. Therefore, the first step in the right direction is to conclude a green electricity contract for charging the battery. This ensures that the total amount of charged electricity has also been generated regeneratively, as Stadtwerke Munchen (SWM) explains in a current article on this topic.

But how much renewable energy actually gets into the vehicle, as long as German electricity is a mix of renewable and gray electricity? In most hours of the year, the demand for electricity is currently higher than the amount of renewable energy fed into the grid at the same time. Renewables generally generate as much electricity as the natural conditions (e.g. B. wind or sun) at that moment. Conventional power plants cover the rest.

Emissions from power generation are falling

According to calculations by the Federal Environment Agency in 2019 (the last year without the impact of the corona pandemic), the average CO2 emissions from all electricity generation in Germany were 408 g/kWh. According to calculations by SWM, an average of 850 g/kWh of CO2 was generated to meet the additional demand for electricity that arises from other large consumers such as electric cars. In the coming years, however, these emissions will continue to decrease, as more and more conventional generation plants are being taken off the grid and renewables are being further expanded.

For the year 2022, SWM is assuming 330 g/kWh for the German electricity mix and around 620 g/kWh for the additional electricity generation that would be necessary for charging e-vehicles.

In any case, e-cars save CO2

Many e-cars are charged uncontrolled. This means that they are simply “plugged in” and charged at full power, regardless of the time and regardless of the energy available in the grid. In such cases of “uncontrolled charging”, the electricity usually comes from conventional generation plants, since charging is also carried out when the demand for electricity is already high, for example at the end of the working day.

But even with this conventionally shaped electricity mix, there is already a clear CO2 advantage compared to conventional combustion engines:
Assuming that the use of one liter of petrol generates 2.33 kg of CO2, with an average consumption of 7.8 liters per 100 km, CO2 emissions are a good 18 kg per 100 km. In the case of an e-car with an average consumption of 20 kWh per 100 km, which is charged without control, it is only 12.4 kg for 2022 according to calculations by SWM. The e-car then avoids a good 5.6 kg of CO2 per 100 km compared to the combustion engine.

Charging during the day is the most ecological

The targeted choice of the charging period plays a significant role when it comes to further improving this saving. Calculations of the SWM show that, in the day between 10 and 17 clock, a particularly low-emission current mix for additional demand by e-cars results. Concretely, the SWM 2022 expect only 570 g CO2 / KWh during this period. The CO2 balance of the electric vehicle thus improves to 11.4 kg of CO2 / 100 km when loaded during the day – the lead to the gasoline engine continues to grow.

The CO2 emission is lower, as the increasing number of solar systems feed a lot of electricity during the daytime into the mains. Often it can even come to a power surplus in the early afternoon hours through the PV feed in the early afternoon hours. If the E-car is loaded during this time, the proportion of actually used renewable energy significantly increases. With the further expansion of solar systems, this effect is amplified: Each system reduces the CO2 load of the electricity mix and thus also the energy stored in the e-car. By 2035, the load from the additional electricity generated during the day is expected to drop to just 200 g CO2 per kWh.

The eco-champion: PV system & charging station

This perspective speaks in favor of significantly expanding the charging options in companies, or. in the case of home office at home. If you also have a PV system on the roof, the energy generated there can flow directly and CO2-free into your own electric vehicle. The more electricity is charged from your own roof, the more climate-friendly charging is.

Due to the limited energy yield per square meter of solar surface, it is only in the rarest of cases that you will be able to generate all the energy for the electric car with your own PV system. By generating your own electricity, however, you can significantly reduce the costs of the operating resources for the electric car, which also clearly reduces the total costs over the lifetime. Having your own PV system not only leads to lower CO2 emissions, but also has a positive effect on your wallet. An electric car that is charged during the day and also uses electricity from its own PV system is therefore the clear eco-champion in motorized private transport.

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5 thoughts on “The right when & how enables low-CO2 electric car charging”

  1. And back to the old stuff..

    For the year 2022, the SWM assumes 330 g/kWh (note.: CO2) for the German electricity mix and of around 620 g/kWh for the additional electricity generation that would be necessary for charging e-vehicles.

    … as if the e-car were responsible for the additional dirty electricity.

    1 liter of gasoline burns too 2.33 kilograms of CO2

    1 liter of diesel burns too 2.64 kilograms of CO2

    (Source: fuel monitor.en)

    Invoice for the year 2022

    330 g CO2 per kWh x 20 (25) kWh charging current over 100 km is the equivalent of 6.6 (8.2) kg CO2.
    620 g CO2 per kWh x 20 (25) kWh charging current over 100 km is the equivalent of 12.4 (15.5) kg CO2.

    Electricity consumption of electric cars: Current models in the ADAC test

    Consumption in the ADAC Ecotest in kWh/100 km

    Hyundai Ioniq Electric Style 16.3


    Renault Zoe R135 Z.E. 50 Intens (52 kWh) 19.0

    VW ID.3 per performance 1st max 19.3

    Tesla Model 3 Standard Range Plus 19.5


    Tesla Model X 100D 24.0

    Audi e-tron Sportback 55 quattro 24.4


    Polestar 2 long range dual engine 29.2

    (Source: – 25.10.2021)

    For comparison, the burners
    Petrol – 2.33 kg CO2 x 7.8 liters per 100 km is 18.174 kg CO2.
    Diesel – 2.65 kg CO2 x 7 liters per 100 km are 18.48 kg CO2.

    Even with dirty electricity, e-cars (BEV) will emit less CO2 than combustion engines in 2022.

    If you take the 2022 electricity mix, since all electricity consumers are in the same boat, then BEVs emit less than half the CO2 into the air compared to combustion engines.

    BEVs have reduced their CO2 rucksack during production after a few years and then drive for many years with much less CO2 emissions than combustion engines, even if they charge a mix of electricity and no green electricity.

  2. I know elctricityMap to retrieve the current CO2 value of the electricity mix. Which app/website can provide a forecast of the CO2 mix of electricity production for the next few days? Then I could adjust my charges to that if possible.

  3. Unfortunately, the marginal electricity is used again in the press release in order to set the CO2 load higher than the general electricity mix. However, one cannot blame new consumers according to the principle “I was there first, you only came now”. That would mean as soon as another major consumer would come along, e.g.B. Hydrolyzers or steel works, cement works, these would be the reason for marginal electricity and e-cars would suddenly be more environmentally friendly because they are then taken into account with the general electricity mix?!??
    The electricity mix is the electricity mix for all consumers and it must quickly reduce its CO2 emissions. Basta.

  4. Now the hour of the beautiful calculator has come again. The small electric cars like my e-up are simply compared with long-distance and transport cars like my Daimler C Kombi Diesel with hitch. Incidentally, it needs 5.2 liters of diesel and not 7 liters. And real consumption, so what I fill up. My e-up really consumes, i.e. what I really charge, approx. 18kWh. Even in this comparison, the diesel is doing well. Comparable e-cars consume approx. 30 kWh per 100 km.
    I load approx. 60% of my PV system. Since my PV electricity would certainly not leave the place, my fellow citizens purchase more gray electricity. It is only substituted.
    And another point: charging is always based on the current electricity mix. Then there is also the complete green electricity in it. However, a large part of this electricity has already been sold to private and commercial customers and is no longer available on the grid. Here the green electricity is counted twice. You should make a decision: either you take the electricity mix, in which case you don’t need green electricity contracts, or you do the math correctly.
    I am in favor of dealing honestly with the matter. Otherwise it could be that no one believes politics and science anymore.


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