CO2 emissions electric cars

With the emergence of the electric car, people start questioning the environmental impact of electric cars, in particular the COemissions. Below you will find an article, based on scientific research, on the CO2 emissions of electric cars and how they compare to gasoline and diesel cars.

WTW, WTT en TTW

When COemissions are discussed, often the following abbreviations are used: WTW, WTT and TTW. Figure 1 shows what each abbreviation stands for.

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Figure 1: Well-to-Wheel, Well-to-Tank and Tank-to-Wheel (European Commission, 23-24 February 2015)

CO2 emissions electricity, gasoline and diesel

CO2 emission factors are factors that are used to calculate the CO2 emissions for organisations and activities. An example of a CO2 emission factor is the Well-to-Wheel (WTW) emission of 2.740 grams of CO2 for every liter of Dutch gasoline (co2emissiefactoren.nl, n.d.).

The Dutch website http://co2emissiefactoren.nl/ was founded by SKAO, Stimular, Connekt Milieu Centraal, the central government and various experts. This website contains a large database of CO2 emission factors. Table 1 shows the relevant CO2 emission factors for cars.

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Table 1: Overview of relevant CO2 emission factors for cars

The Dutch grey energy is, for approximately 30%, generated by coal, the rest is generated by natural gas and nuclear power. The average Dutch energy mix is a mixture of, i.a., coal, natural gas, nuclear power, biomass, solar, wind and hydropower (CBS, February 2015).

CO2 emissions related to car usage

When the CO2 emissions of a car are calculated, usually only the direct emissions are being taken into account. The New European Driving Cycle (NEDC) only considers the direct emissions and therefore only the Tank-to-Wheel (TTW) emissions. This is the reason for fully electric cars to be publicized as zero-emission. In order to make a fair comparison between electric and fossil fuel cars, the indirect (WTT) emissions should be taken into account as well.

To compare electric cars with fossil fuel cars, the CO2 emissions of different electric cars have been calculated. The electric cars are the Tesla Model S P90D (90 kWh), Tesla Model X 100D (100 kWh), Nissan Leaf (30 kWh), Renault Zoe (41 kWh), Opel Ampera-e (60 kWh), VW e-Golf (35,8 kWh), BMW i3 (33 kWh), and Hyundai Ioniq (28 kWh). These cars have been tested by EcoTest (EcoTest, n.d.). The Tesla Model S 75D and Model X 75D are more efficient, but since EcoTest has not tested these versions yet, they are not included.

The EcoTest data is used for the electricity consumption. The EcoTest is performed in Germany and takes into account the charge loss of charging electric cars by reading out the used energy by the charger (EcoTest, n.d.). The consumption per 100 km for these electric cars, including charge loss, can be found in table 2.

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Table 2: Energy consumption electric cars including charge loss

To calculate the CO2 emissions of the electric cars, the information in table 1 and table 2 can be combined. Table 3 provides an overview of the CO2 emissions and a comparison of the fuel consumption of gasoline and diesel cars to match the emissions of electric cars.

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Table 3: Overview of CO2 emissions electric cars and comparison with gasoline and diesel cars

Table 3 shows the difference in CO2 emissions between electric cars and cars running on fossil fuel. The difference between grey and average energy is significant, but even electric cars using grey energy are causing less CO2 emissions than comparable cars on gasoline or diesel.

CO2 emissions life cycle car

The indirect and direct CO2 emissions related to usage of the car are not complete without taking into account the CO2 emissions that are caused by producing and recycling the car.

If 100% coal powered energy is used to charge the electric car, the electric car causes 4% less CO2 emissions compared to a similar gasoline or diesel car (TNO, 14 July 2014). Coal powered electricity causes 935 grams of CO2 per kWh (TNO, 14 July 2014), the Dutch energy mix causes 355 grams of CO2 per kWh  (co2emissiefactoren.nl, n.d.).

Research from TNO shows that electric cars have less CO2 emissions than hybrid-cars and gasoline and diesel cars. The research takes the life cycle of the car into account, from producing to recycling and disposal. Looking at the life cycle of the car, an electric car causes, on average, 35% less CO2 emissions compared to a similar gasoline or diesel car (TNO, 7 April 2015).

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Figure 2: CO2-emissions of conventional and electric cars based on 220.000 km / 136.701 miles. Fabricage (production) includes maintenance and recycling (TNO, 7 April 2015)

Looking at the electricity production by source, it is safe to say The Netherlands has relatively grey, or dirty, electricity. Figure 4 provides an overview of the electricity production by source for Europe and the individual countries (Eurostat, 9 November 2015).

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Figure 3: Breakdown of electricity production by source, 2014

It is safe to say The Netherlands is producing a relatively high percentage of its electricity by fossil fuels (mostly coal and natural gas) compared to the rest of Europe. This means that the CO2 emissions per kWh are relatively high in The Netherlands. Having this information, it can be concluded that electric cars are causing less CO2 emissions in Europe than in The Netherlands.

Conclusion

In The Netherlands the electric car, using grey electricity, is causing significantly less CO2 emissions than a similar gasoline or diesel car.

A point of discussion that is not yet discussed, is the CO2 emission factor for electricity that is reported by some organisations to calculate the CO2 emissions of electric cars. This CO2 emission factor is based on grey energy and therefore provides the highest possible CO2 emissions for electric cars. As mentioned before, grey energy comprises of coal, natural gas and nuclear power. Since the average energy mix is also comprised of renewable energy sources, using the emission factor for grey electricity is misleading. For gasoline and diesel there is no room for discussion, since there is (in essence) only one type of gasoline and one type of diesel. It is unfair and misleading to use the grey energy emission to calculate the CO2 emissions of an electric car. It is less unfair to use the CO2 emission of the average energy mix, although that is still not considering electric cars that only use renewable electricity.

Individuals who would like to calculate their CO2 emissions caused by the usage of their cars, are advised to use the CO2 emission that reported on their energy label. This CO2 emission is the most accurate since it comes directly from the supplier.

Literature

CBS. (February 2015). Elektriciteit in Nederland. Consulted on 2 February 2016, from: http://www.cbs.nl/NR/rdonlyres/D694C055-66E0-49D4-A0EA-7F9C07E3861E/0/2015elektriciteitinnederland.pdf

Co2emissiefactoren.nl. (n.d.). Lijst emissiefactoren. Consulted on 9 December 2017, from: http://co2emissiefactoren.nl/lijst-emissiefactoren/#brandstoffen_voertuigen

EcoTest. (n.d.). ADAC Ecotest. Consulted on 9 December 2017, from: https://www.adac.de/infotestrat/tests/eco-test/default.aspx

European Commission. (23-24 February 2015). JEC Well-to-Wheels: considerations on methodology choices. Downloaded on 1 February 2016, from: https://www.concawe.eu/uploads/Modules/Events/Laura%20Lonza_JRC_Concawe%20Symposium.pdf

Eurostat. (9 November 2015). Electricity production and supply statistics. Consulted on 7 February 2016, from: http://ec.europa.eu/eurostat/statistics-explained/index.php/Electricity_production_and_supply_statistics

TNO. (14 July 2014). Indirecte en directe CO2-uitstoot van elektrische personenauto’s. Consulted on 2 February 2016, from: https://www.tno.nl/media/4404/tno-2014-notitie-directe-en-indirecte-emissie-elektr-voertuig_-14072014.pdf

TNO. (7 April 2015). Energie- en milieu-aspecten van elektrische personenvoertuigen. Consulted on 2 February 2016, from: https://www.rvo.nl/sites/default/files/2015/04/TNO%20Factsheets%20Elektrische%20Voertuigen.pdf

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