More than half a million of electric cars were sold in the world in 2015, 40% in China and 20% in the US (1). Presented as a solution for climate change, electric cars are however harmful and sometimes even more than gas and diesel cars from life cycle analysis.
Depending where...
Batteries manufacturing is a highly energy consuming process. But the main reason why electric vehicles carbon footprint can be significant is the way electricity is produced. Indeed electricity emission factor is different according to the type of power plants (coal, natural gas, nuclear, hydroelectricity, windpower...). So greenhouse gases (GHG) emissions of an electric car change a lot from a country to another, due to the type of power plants.
Driving one kilometer in an electric car in Poland, China or India, where more than 80% of electricity is generated from coal produces more carbon dioxide (about 250 gCO2e) than in a gasoline car (180 gCO2e) (2). Biofuel cars produce about 120 gCO2e/km (3).
In France, electric car carbon emission factor is around 90 gCO2e per km, since nuclear power don’t produce GHG (but however radioactive wastes). Norway is often given as an example because one car sold out of 4 is electric and the government plans to forbid thermic cars by 2025. But in Norway, electricity is mainly produced by hydro plants.
...and when
Carbon footprint is also highly determined by the moment of the day batteries are reloaded. Electricity production is changing all along the day according to demand. In France, base load production is made by nuclear power plants, but peak demand (in winter or morning, noon and evening) is covered by fuel power plants and imports. Electricity emission factor can change for 1 to 5 according to season and hour of the day (3). An electric car with batteries reloaded after work (between 17.00 and 22.00) in winter would have a carbon footprint over 200 gCO2e/km (compared to 78 gCO2e/km with night reloaded batteries) (4).
On the basis of 2 millions electric cars in France by 2020, the Regulation Authority forecast that peak demand would rise of 11%, an increase of 10 GW, either more than 6 EPR nuclear power plants (5).
To make electric cars a real solution to fight climate change, renewable energies must be expanded. Technical solutions and financial incentives must also be implemented in order to have batteries reloaded in low demand periods.
Footnotes & references
(1) International Energy Agency : https://www.iea.org/publications/.../Global_EV_Outlook_2016.pdf
(2)« gCO2e » means gram of carbon dioxide equivalent and is the main unit for greenhouse gases measurement
(3) E85 biofuel available in France is a mix of gas and bioethanol, which share is between 65 % and 85 %.
(4) 2015 Annual Report of French Electricity Grid: http://www.rte-france.com/sites/default/files/2015_bilan_electrique.pdf
(5) From an intern memo of French Electricity Grid and French Agency for Energy & Environment : http://www.agirpourlenvironnement.org/pdf/contenuCO2longue.pdf
(6) French Energy Regulation Authority: http://www.smartgrids-cre.fr/index.php?p=vehicules-electriques
