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Do electric cars cause more or less climate pollution than gasoline cars? Take a look.

Electricity has arrived as a fuel source for an increasing number of vehicles. Will this increase or decrease climate pollution compared to using gasoline?

I've heard so much confusion about this that I decided to make one of my Visual Carbon charts to allow informed comparisons at a glance. Turns out this was easier imagined than done. Determining the climate pollution from electric-fuelled vehicles requires compiling data on three new variables:

  1. ELECTRICITY: The amount of climate pollution released when generating electricity varies dramatically between regions. This is the primary factor determining how much climate pollution an electric vehicle causes.
  2. MAKING THE CARS: Making electric cars and their batteries is significantly different than making old-school gasoline cars. Studies show that the climate pollution is higher to make electric vehicles.
  3. BATTERY REPLACEMENT: The climate impact of replacing traction batteries during the lifespan of an electric car needs to be considered.

After two weeks of dissecting geeky studies, wading through energy databases and hunting through industry websites I found what I needed. The result is the chart below.

Chart notes:

  • Each bar in my chart shows the climate pollution released from building, and then driving, a particular vehicle.
  • The different colours in each bar represent: making the car (black); making the traction battery (purple); burning gasoline (brown) and generating electricity for fuel (orange).
  • The top rows show climate pollution from a typical all-electric vehicle. Next is a plug-in hybrid that uses both electricity and gasoline. At the bottom is a range of gasoline-only vehicles.
  • For electric-fuelled vehicles, several electricity scenarios are provided to show a range from dirtiest to cleanest.
  • You can click the chart to view it full size.


The big picture

Four main conclusions leap out of this chart for me.

1 -- In most regions, cars fuelled by electricity create less climate pollution than the very best all-gasoline fuelled car.

In regions with very high percentages of renewable electricity -- like BC, Ontario and Quebec -- the total climate pollution from electric vehicle is less than half what is created by the best gasoline-only cars. In BC, for example, an electric Nissan Leaf will create just 30% of the climate pollution that the best all-gasoline car does.

2 -- In dirty electricity regions, driving on electricity creates similar climate pollution to gasoline.

Regions that burn mostly coal and natural gas to generate electricity create high levels of climate pollution for each kWh. In Alberta, for example, a Plug-In Prius will cause a similar amount of climate pollution driving on gasoline as it does driving on Alberta's electricity.

Some electric car owners have worked around this problem by putting up their own solar panels, or by purchasing cleaner electricity directly from their utility.  

3 -- The climate pollution from burning gasoline vastly exceeds the climate pollution from making the car.

The average US car weighs around 1.5 tonnes but burns nearly 30 tonnes of gasoline. Thirty tonnes. For perspective that much gasoline would fill a stack of oil barrels much higher than the world's tallest tree, the Statue of Liberty or the Canadian Parliament.

As my chart shows, this gasoline causes 102 tonnes of CO2 (tCO2) while building the vehicle itself causes just 7 tCO2. Driving the car, not making it, causes almost all the climate damage.

4 -- There is a gigantic difference in how much climate pollution comes from today's cars.

For example an electric car fuelled by BC electricity will emit a tenth as much climate pollution (15 tCO2) as a large gasoline fuelled SUV (over 160 tCO2). Even within the ranks of all-gasoline cars, the difference can be over 100 tCO2.


Below I answer some of the most common questions I come across about climate pollution from electric and gasoline vehicles.

Q: How much climate pollution is created making an electric car and its battery?

A: Around 14 tCO2 = twice as much as for making an average gasoline-only car

DISCUSSION: Researchers have done several studies on this. The study I used estimates that twice as much CO2 is released building an EV as building an average gasoline-only car. Most of the difference is caused by creating the large traction battery. Specifically the study estimated:

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