How to evaluate the electric vehicle’s carbon footprint?
In order to understand the electric vehicle’s “well-to-wheel” carbon footprint, two phases must be distinguished: energy production and vehicle use. In the use phase, the electric vehicle does not emit any C02, but it does consume a certain quantity of “outlet-to-wheel” energy. In fact, the battery needs to be charged in order to drive the vehicle. This energy expenditure, measured in kWh, can be related to each kilometre or every 100 km travelled in order to make an analogy with thermic vehicles.
In the energy production phase, which is necessary to charge the battery, the “well-to-outlet” C02 emissions are variable. The average number of C02 grams emitted per kWh and distributed to the outlet depends on the energy mix. In France, this C02 content is in the region of 85 g/kWh, which is much less than the European average (of around 400 g/kWh). And for good reason: the electricity produced in France comes predominantly from nuclear power (80%), with the balance coming from water-powered stations (15%) and from gas or coal (5%), according to the IEA (the International Energy Agency). The situation is different elsewhere in the world where nuclear power and renewable energy are rarer. It hits 850 g/kWh in China and 875 g/kWh in India. Electricity in those countries thus has high carbon content as it is produced in the majority by coal-powered stations.
Ultimately, in order to calculate the C02 emissions per kilometre of an electric vehicle, one has to multiply the average annual C02 content of a country (in g/kWh) by the consumption of the vehicle (in kWh/km). This latter fluctuates, depending on the electric vehicle, between 0.15(1) and 0.25 kWh/km according to ADEME (the French Environment and Energy Management Agency). One therefore achieves a result in grams of C02/km that can be compared to that of a thermic vehicle.
(1) Renault’s Fluence family saloon claims consumption of 0.15 kWh/km (or the lowest value of ADEME’s criteria), thanks in particular to its braking energy recovery mechanism.
Figures and hypotheses
According to Maxime Pasquier at ADEME, an electric vehicle’s carbon footprint (of the Renault Fluence type) is between 12 and 20 g/km in France, because of the dominant nuclear power. However, elsewhere in Europe, with the current energy mix, this same vehicle will have a footprint of between 60 and 100 g/km. Only in the extreme case of China, because of its huge use of coal-powered stations, does the EV footprint become greater: between 127 and 212 g/km. This case, however, should not serve as a benchmark, especially as the country’s energy distribution is constantly evolving.
The fact remains that the electric vehicle should allow C02 emissions in Europe to be substantially reduced. This scenario is corroborated by IEA (International Energy Agency) figures. According to François Cuenot, analyst in the Transport department, “the average thermic vehicle in 2010(2) emits 32 tons of C02 during its total lifespan (10 years on average)”. Over the same lifespan, the electric vehicle discharges “between 2 tons of C02 in the best of cases (in France) and 24 tons in the worst (in China)”. A range that says a lot about the electric vehicle’s environmental potential.
(2) According to the IEA, the average thermic vehicle, taken from the worldwide number of cars on the road, covers 15,000 km (9,320 miles) per year over 10 years, or 150,000 km (93,200 miles) over its total lifespan. In 2010, this vehicle is, on average, 8 years old (the average age of the worldwide number of cars) and consumes around 8.5 l/100 km. In the end, it emits 213 g/km of C02, including well-to-tank emissions (up to 10% of the vehicle’s total emissions).
