Are electric cars really greener than gasoline cars?

Canada is stepping up efforts to reduce its greenhouse gas (GHG) emissions, in particular by encouraging the electrification of transport.

In particular, the federal government intends to require that at least 20% of new vehicle sales be zero-emission vehicles within four years. Eventually, Ottawa will require 100% of cars sold to be electric by 2040.

Louis Haché, from Dieppe, wonders, however, whether the electric car is even more ecological than the conventional gasoline car.

To find out, Science Matters turned to Jennifer Dunn, an object lifecycle expert at the Center for Sustainability and Resilience Engineering and a professor at Northwestern University in Toronto, Ontario.

The answer, says the expert, is yes. However, we should not be deceived, the electric car (EV) is not without consequences for the environment.


Unlike gasoline-powered cars, which release many polluting compounds from their exhaust pipes, including GHGs, EVs are emission-free.

When we look at how they’re made, however, it’s an entirely different story.

The problem is mainly in the extraction of precious metals – cobalt, nickel, copper, lithium – used in the manufacture of batteries for electric cars.

Its extraction and purification require large amounts of energy, sometimes obtained from the combustion of polluting sources such as coal.

“These metals are problematic in different ways,” says Jennifer Dunn. For example, sulfur is found in ore that contains nickel. During purification in smelters, this produces sulfur oxide emissions, implicated in acid rain. As some smelters are located in countries where there are few environmental standards, this can cause local problems of acid rain and significant GHG emissions as it is a very energy demanding process.”

Extraction of lithium — often called white gold because global demand for this metal has exploded in recent years — generates few GHGs but brings other challenges.

Most of the world’s lithium reserves are found in South America (Chile, Bolivia, Argentina), in the salt lakes of the Andean altiplano. Lithium salts are obtained by pumping water from these lakes and letting it evaporate to harvest the precious metal. Although this process requires relatively little energy, the practice is beginning to threaten the region’s ecosystems and create water supply problems for the populations of these regions.

By wanting to solve an ecological problem by ditching gasoline-powered cars, we will end up creating new ones and they will likely get worse as global demand for EVs increases.

Part of the solution could come from electric car battery recycling techniques to recover the metals used in their manufacture. At the moment, these processes do not allow the recycling of lithium from batteries, but many research processes are being developed to make this possible.

a better balance

The production of an EV can be up to twice as polluting as that of a gasoline car, but its GHG emissions balance over its lifetime remains better.

“For every kilometer driven, there are fewer GHG emissions than a conventional car, even taking into account the extraction of the metals used to make the batteries,” says Dunn.

However, the EV must travel a certain distance before it has a more interesting GHG emissions balance than a conventional car.

In a study published by Hydro-Quebec in 2016, it was observed, for example, that an electric car had to drive more than 32,000 km in Quebec before it had a better emissions record.

After this distance, a conventional car emits more and more GHG over its lifetime. For example, after driving 150,000 km, an EV will have emitted 65% less GHG than a gasoline-powered car that traveled the same distance. At 300,000 km, there are 80% less emissions.

Obviously, this balance is less good in places where the electricity used to recharge EV batteries comes from a polluting energy source.

Social impact of electric cars

Traditionally, scientists interested in analyzing the life cycle of objects measured their environmental impact without, however, paying attention to the social consequences of their manufacture.

Jennifer Dunn therefore teamed up with social scientists to understand the human impacts of nickel mining in the Democratic Republic of Congo.

In a study published in December, researchers found that this industry was notably associated with an increase in violent conflict and food insecurity. Some Congolese also reported being forced to leave their homes or farms and work in unsafe conditions.

“Electric cars play an important role in addressing the climate crisis, but it is important to look closely at the supply chain for these metals and do everything possible to reduce the environmental and social impact on the communities where they are mined,” says Jennifer Dunn.

Acadie Nouvelle journalist Justin Dupuis answers your science questions every Saturday. You can send yours to:

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