Thursday, October 14, 2021

Electric Vehicles Must Get Lighter

Here's something I didn't know until I read this article in Nature: electric vehicles are heavier than their equivalent fossil-fuel-powered model. For example, Ford's electric F-150 will be 700 kg heavier than the gasoline version. This is not a good thing, for several reasons. 

Electrifying vehicles adds yet more weight. Combustible, energy-dense petroleum is replaced by bulky batteries. And the rest of the vehicle must get heavier to provide the necessary structural support1. The electric F-150 weighs 700 kg more than its petrol-powered predecessor. Smaller electric cars are heavier than their petrol equivalents, too (see ‘Heavier electric fleet’).

Why does this matter? First and foremost is safety. The likelihood of passengers being killed in a collision with another vehicle increases by 12% for every 500-kg difference between vehicles2. This added risk wouldn’t apply if everyone drove cars of similar heft. But until they do, the number of casualties in crashes is likely to increase as heavy electric vehicles join lighter existing fleets. Pedestrians will also be at risk. If US residents who switched to SUVs over the past 20 years had stuck with smaller cars, more than 1,000 pedestrian deaths might have been averted, according to one study3.

Heavier vehicles also generate more particulate pollution from tyre wear. They require more materials and energy to build and propel them, adding to emissions and energy use.

How big a problem is this extra weight? A rough comparison between mortality costs and climate benefits shows that it is significant. Under the energy systems operating in most countries today, the cost of extra lives lost from a 700-kg increase in the weight of an electrified truck rivals the climate benefits of avoided greenhouse-gas emissions. 

I would still buy an electric vehicle, assuming the cost came down to the point where I could afford it, but I would factor weight into my consideration when looking for one.

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