Electrification of vehicles is necessary to reduce greenhouse gas emissions, but in Quebec the increasing weight of the battery-powered vehicles could cause electricity demand to rise well beyond projections.

That’s the conclusion of an analysis by Université de Montréal researchers Frédérik Lavictoire and Simon Brassard, supervised by Normand Mousseau, a professor in the Department of Physics.

Their results are published in the journal Sustainable Futures.

Cars are getting heavier

Between 2011 and 2021, the average weight of vehicles sold in Quebec increased by 11 kg per year for over 10 years, from 1,566 kg to nearly 1,700 kg.

New vehicles weigh an average of 135 kg more than the existing fleet average, while vehicles that are being retired are 104 kg lighter. A vehicle purchased today weighs an average of 110 kg more than the one it replaces.

With 60,000 vehicles being added to Quebec’s fleet each year, the cost of maintaining the road network—and the electrical grid—is likely to be steep, the UdeM researchers say.

Small SUVs, which accounted for 12.6% of the fleet in 2011, have surged in popularity to reach 28.3% in 2021. They have been the leading category since 2020.

Meanwhile, compact vehicles declined from 28.5% to 25.4% of vehicles on the road, and sedans and minivans fell from 19.7% to 14.6%.

With their heavy batteries, EVs in Quebec now weigh about 23% more than gas-powered vehicles, or an extra 344 kg.

Heavier vehicles also take a toll in terms of premature wear and tear on the roads and more serious injuries in accidents. And as they continue to get heavier, they also put a strain on Quebec’s power grid.

Between 2021 and 2040, the UdeM researchers project that the amount of electricity used by EVs in the province will increase from 0.24 terawatt hours (TWh) to 29.03 TWh.

Harsh winters increase demand

EVs accounted for about 13.6% of Quebec’s total electricity demand in 2019. By 2030, when the government aims to have two million EVs on the roads, EV consumption would reach 7.68 TWh.

That’s roughly consistent with Hydro-Québec’s projection of 7.8 TWh for 2032.

However, Mousseau is concerned about the grid’s capacity in the province’s harsh winter months, when cold spells can be protracted and extreme.

EVs use more power in winter than in summer because cold temperatures reduce battery efficiency, increase tire friction and increase air density.

In January, when the average temperature is -10.3°C, monthly EV consumption will rise to 3.1 TWh once Quebec’s vehicle fleet is fully electrified, compared with 1.9 TWh in August, the UdeM researchers project.

At -20°C, the required capacity is almost double that on a summer day.

“In winter, we need to control electricity usage because adding capacity to meet peak demand costs $150 to $200 per kilowatt,” Mousseau said.

“With a fully electrified fleet in 2040, EVs would require an average additional capacity of 5,261 megawatts when the temperature is -20°C. That’s 12.1% of the total peak demand recorded in 2022.

“If the increasing weight of the EV fleet adds another gigawatt to peak demand, it will cost hundreds of millions of dollars more to generate that electricity.”

Three possible scenarios

The researchers modeled three scenarios for the period 2021-2040.

In the first, they allow the trend toward heavier vehicles to continue without intervention. In this case, the average mass would increase to 2,114 kg by 2040. The fleet’s annual electricity consumption would increase to 29.03 TWh and the additional required capacity on a cold winter’s day would be 5,261 megawatts.

In the second scenario, the increase in weight is limited to the weight of the EV battery: on average in Quebec, about 344 kg.

In the third scenario, the average vehicle weight is frozen at the 2021 level of 1,566 kg. This would reduce EV electricity demand by 17.6% in 2040, from 29.03 to 23.91 TWh. The required capacity on a -20°C day would drop from 5,261 to 4,332 megawatts.

The saving of almost 6 TWh is equivalent to three percent of Hydro-Québec’s current total production. It would avoid the need to build costly infrastructure that would be needed only for a few hours a year, during winter peaks.

In scenario 1, by 2035, EVs will require additional capacity of 3,232 megawatts when the temperature is -20°C. That is 40.4% of all the additional power projected in Hydro-Québec’s action plan by 2035.

“Electrification of the vehicle fleet will entail system costs that will have to be borne,” said Mousseau. “We believe that reducing the average weight of vehicles is one solution that should be explored.”

Regulations could make batteries lighter

How can the weight of EVs be reduced? The researchers suggest several possibilities.

One is to reduce the weight of the battery, a significant technological challenge but one they believe is achievable with technological progress.

“Between 2017-2018 and 2021-2022, batteries were improved to increase range, but unfortunately, this improvement also increased the weight of the vehicles,” Mousseau said.

The simplest solution would be to amend the existing “Act to increase the number of zero-emission motor vehicles in Québec,” he suggested.

“Manufacturers could be required to comply with a specific average weight, or to offset the additional weight by paying a fine or tax.”

This approach, which has proven effective in stimulating the production of EVs, could also be used to control their weight, Mousseau said.

“For example, Tesla has benefited from the credit transfers allowed by the Act, demonstrating that it is possible to have manufacturers, not consumers, bear the cost of design choices.”

‘Strong global pressure’

Although the Quebec government recently backtracked on banning the sale of gasoline-powered vehicles by 2035, Mousseau is confident about the future of electrification.

“There is strong global pressure: the electrification of road vehicles will happen,” he said.

By postponing electrification, “Quebec is temporarily burying its head in the sand, but it cannot indefinitely block access to more efficient and less expensive electric vehicles, such as those made in China.”

Mousseau also pointed to an important economic issue: “For 20 years, we have watched other countries develop green technologies. What will we be producing 20 years from now, if we keep letting others take the lead? If we don’t put our foot on the accelerator, there’ll be significant economic risks.”