This is how many kilometres it takes for an EV to become cleaner than a petrol car

You glide silently out of the Tesla showroom in your sleek new electric Model 3, satisfied you're looking great and doing your bit for the planet.

But keep going — you'll have to drive another 21,725km before you're doing less harm to the environment than a petrol-guzzling saloon.

That's the result of a Reuters analysis of data from a model that calculates the lifetime emissions of vehicles, a hotly debated issue that's taking centre stage as governments around the world push for greener transport to meet climate targets.

The model was developed by the Argonne National Laboratory in Chicago and includes thousands of parameters from the type metals in an electric vehicle (EV) battery to the amount of aluminium or plastic in a car.

Argonne's Greenhouse Gases, Regulated Emissions and Energy Use in Technologies (GREET) model is now being used with other tools to help shape policy at the US Environmental Protection Agency (EPA) and the California Air Resources Board, the two main regulators of vehicle emissions in the US.

Jarod Cory Kelly, principal energy systems analyst at Argonne, said making EVs generates more carbon than combustion engine cars, mainly due to the extraction and processing of minerals in EV batteries and production of the power cells.

But estimates as to how big that carbon gap is when a car is first sold and where the “break-even” point comes for EVs during their lifetime can vary widely, depending on the assumptions.

Kelly said the payback period then depends on factors such as the size of the EV's battery, the fuel economy of a petrol car and how the power used to charge an EV is generated.

Norway's a winner:

Reuters plugged a series of variables into the Argonne model, which had more than 43,000 users as of 2021, to come up with some answers.

The Tesla 3 scenario above was for driving in the US, where 23% of electricity comes from coal-fired plants, with a 54kWh battery and a cathode made of nickel, cobalt and aluminium, among other variables.

It was up against a petrol-fuelled Toyota Corolla weighing 1,358kg with a fuel efficiency of 7,1l/100km. It was assumed both vehicles would travel 278,659km during their lifetimes.

But if the same Tesla was being driven in Norway, which generates almost all its electricity from renewable hydropower, the break-even point would come after just 13,518km.

If the electricity to recharge the EV comes entirely from coal, which generates the majority of the power in countries such as China and Poland, you would have to drive 126,655km to reach carbon parity with the Corolla, according to the Reuters analysis of data generated by Argonne's model.

The Reuters analysis showed that the production of a mid-sized EV saloon generates 47 grams of carbon dioxide (CO2) per mile during the extraction and production process, or more than 8.1m grams before it reaches the first customer.

By comparison, a similar petrol vehicle generates 32g/km or more than 5.5m grams.

Michael Wang, senior scientist and director of the Systems Assessment Centre at Argonne's Energy Systems division, said EVs then generally emit far less carbon over a 12-year lifespan.

Even in the worst case scenario where an EV is charged only from a coal-fired grid, it would generate an extra 4.1m grams of carbon a year while a comparable petrol car would produce over 4.6m grams, the Reuters analysis showed.

'Well-to-wheel:'

The EPA told Reuters it uses GREET to help evaluate standards for renewable fuel and vehicle greenhouse gases while the California Air Resources Board uses the model to help assess compliance with the state's low-carbon fuel standard.

The EPA said it also used Argonne's GREET to develop an online program that allows US consumers to estimate the emissions from EVs based on the fuels used to generate electric power in their area. 

The results of the Reuters analysis are similar to those in a life-cycle assessment of electric and combustion-engine vehicles in Europe by research group IHS Markit.

Its “well-to-wheel” study showed the typical break-even point in carbon emissions for EVs was about 24,140 to 32,186km, depending on the country, according to Vijay Subramanian, IHS Markit's global director of carbon dioxide (CO2) compliance.

He said using such an approach showed there were long-term benefits from shifting to electric vehicles.

Some are less positive about EVs.

University of Liege researcher Damien Ernst said in 2019 that the typical EV would have to travel nearly 700,000km before it emitted less CO2 than a comparable petrol vehicle. He later revised his figures down.

Now, he estimates the break-even point could be between 67,000km and 151,000km. Ernst told Reuters he did not plan to change those findings, which were based on a different set of data and assumptions than in Argonne's model.

Some other groups also continue to argue that EVs are not necessarily cleaner or greener than fossil-fuelled cars.

The American Petroleum Institute, which represents over 600 companies in the oil industry, states on its website: “Multiple studies show that, on a life-cycle basis, different automobile power trains result in similar greenhouse gas emissions.”

Argonne National Laboratory is funded by the US department of energy and operated by the University of Chicago.

FACTBOX:

Reuters analysed data generated by an Argonne National Laboratory model to determine at what point a typical electric vehicle (EV) becomes cleaner than an equivalent petrol car in terms of its lifetime carbon footprint.

Based on a series of assumptions, the data showed that a Tesla Model 3 in the US, for example, would need to be driven for 21,725km before it does less harm to the environment than a Toyota Corolla.

Following are the assumptions Reuters plugged into the Argonne model to produce different break-even scenarios, depending on how the power used to charge an EV is generated.

MID-SIZE SALOON:

Tesla Model 3 (EV) vs Toyota Corolla (petrol)

Lifetime vehicle miles travelled: 278,659km

Fuel economy (petrol): 7,1l/100km

Curb weight: Model 3 — 1,625kg, Corolla — 1,340kg

EV battery range: 482km

EV battery type: Lithium-ion EV battery size: 54kWh

EV battery cathode material: nickel-cobalt-aluminium (NCA)

Power scenario 1: 100% hydroelectric Break-even point: 13,518km

Power scenario 2: US average energy mix (23% coal-fired, plus other fossil fuels and renewables) Break-even point: 21,726km

Power scenario 3: 100% coal-fired Break-even point: 126,655km

MID-SIZE SUV:

Tesla Model Y (EV) vs Honda CR-V (petrol)

Lifetime vehicle miles travelled: 295,094km

Fuel economy (petrol): 7,8l/100km

Curb weight: Model Y — 2,003kg, CR-V — 1,513kg

EV battery range: 482km

EV battery type: Lithium-ion

EV battery size: 60kWh

EV battery cathode material: nickel-cobalt-aluminium (NCA)

Power scenario 1: 100% hydroelectric Break-even point: 14,805

Power scenario 2: US average energy mix (23% coal-fired, plus other fossil fuels and renewables) Break-even point: 123,818km

Power scenario 3: 100% coal-fired Break-even point: 143,231km