Feature Article: How much CO2 do electric vehicles, hybrids and gasoline vehicles emit?
Release date: 2018-09-12
The adoption of electric vehicles (EVs) can contribute to greenhouse gas (GHG) emissions reductions. However, this depends on the source of electricity that will power EVs. EVs can be partly or wholly powered by electricity purchased from the grid, which has different carbon intensitiesFootnote 1 depending on where you are in the country. In some provinces, like Quebec, Manitoba and British Columbia, some EVs can emit almost no carbon dioxide (CO2), because these provinces have low-carbon electricity generation. As it is explained in this article, in some provinces, the emissions from burning fuel for electricity generation can be more than the emissions from burning gasoline in the engines of some conventional vehicles.
By the second quarter of 2018, Canada had about 69 000 EVs, which represented about 0.2% of the total number of registered vehicles.Footnote 2
Do electric vehicles emit CO2?
Although electric motors do not emit CO2 when they run, CO2 can be emitted during the generation of electricity that EVs draw from the electrical grid and store in their batteries. The carbon-intensity of electricity generation varies by province because each province generates electricity differently.Footnote 3 For example, some provinces heavily rely on hydro power while others rely more on coal-fired power plants.
The bar chart below shows potential emissions from different 2018-model vehicles, including battery electric, plug-in-hybrid, hybrid electric, and gasoline. Emissions are shown by province and territory. Emissions for each vehicle are based on its potential electric and gasoline emissions, where applicable.Footnote 4 This article does not include lifecycle emissions of mining raw materials, manufacturing, shipping, and scrapping the vehicle, or from the production of fuel. These emissions comparisons only examine the emissions from the combustion of fuel, whether from a power plant generating electricity or from a vehicle consuming gasoline, as applicable. While there are emissions related to producing the fuel that goes into vehicles or power plants, be it refining gasoline, mining coal or extracting natural gas, these emissions are not included here. This bar chart only shows a sample of vehicle models. For information on more vehicle models, see Natural Resources Canada’s Vehicle Emission Comparison Tool.
The shaded map below shows the consumption carbon-intensities of electricity in each province and territory. Consumption carbon-intensity is the amount of GHGs emitted per unit of electricity consumed. This describes the emissions from the electricity that is consumed in each province or territory, which may not be the same as the emissions from the electricity generated in that province or territory. This includes line loss, which is lost energy from resistance in transmission lines, and includes electricity imported from other jurisdictions.
- Internal combustion engine (ICE): ICE vehicles are normally fueled with gasoline or diesel. When the fuel is combusted, expanding gases push pistons and turn a drive shaft that propels the vehicle. These are also referred to as conventional vehicles.
- Battery electric vehicle (BEV): BEVs are powered by electricity, which is stored as chemical energy in batteries. The energy powers an electric motor that propels the vehicle.
- Hybrid electric vehicle (HEV): HEVs are like a combination of ICE vehicles and BEVs. There are two main kinds of HEVs. Some HEVs use gasoline or diesel to fuel a generator that charges a battery and/or powers an electric motor that propels a vehicle. Other HEVs use an ICE to propel a vehicle while an electric motor assists during acceleration. Unlike fully electric vehicles, HEVs are only fueled with petroleum and their emissions do not depend on the regional electricity grid. The HEV’s battery is charged during “regenerative braking”, when brakes convert kinetic energy to electrical energy to slow the vehicle. The batteries can also be charged when the ICE acts as a supplemental generator.
- Plug-in hybrid electric vehicle (PHEV): PHEVs are HEVs whose batteries can also be charged by plugging the vehicle into a power source. This means PHEVs can operate as either a BEV or a HEV. In this article, PHEVs are modeled as running on electricity only.
Source and Description
Description: This bar chart shows the CO2 emissions of different vehicles per kilometre driven. The emissions from EVs and PHEVs change depending on the province, but the emissions from HEVs and ICE vehicles do not. There is a menu to select different provinces and territories. Alberta and Quebec represent the upper and lower emissions bounds because they are respectively the most and least carbon intensive provincial grids. In Alberta, compact HEVs emit the least. There are EVs and PHEVs that emit more than some gasoline vehicles. In Quebec, EVs and PHEVs emit almost nothing while the highest emitting vehicles are gasoline trucks and minivans.
This shaded map shows the carbon-intensities of electricity consumption by province in grams of CO2 equivalent per kWh. The maps shows the following:
British Columbia: 11.7; Alberta: 900; Saskatchewan: 730; Manitoba: 2.2; Ontario: 40; Quebec: 1.7; Newfoundland and Labrador: 40; New Brunswick: 350; Nova Scotia: 690; Prince Edward Island: 350; Yukon: 50; Northwest Territories: 220; Nunavut: 760.
Why are emissions from electric vehicles so different across provinces?
If an EV is charged from the grid, its emissions depend on the generation-mix of local power generation. Quebec, British Columbia, Manitoba, Newfoundland and Labrador, and Yukon, have less carbon-intensive generation because of abundant hydro resources. Ontario has a lower carbon-intensity because of a large amount of nuclear generation. Conversely, grid-charged EVs in Alberta, Saskatchewan, Nova Scotia, and Nunavut emit more GHGs, because Alberta, Saskatchewan, and Nova Scotia generate a large share of their electricity from coal while Nunavut generates a large share of its electricity from diesel.
However, charging from the grid is not the only option for owners of electric vehicles. Distributed generation, such as roof top solar, is a growing source of non-emitting electricity generation. In the future, it could allow EVs to lower their emissions even more, because charging stations at homes and at businesses can become less dependent on a grid’s carbon intensity.
Where are electric vehicles in Canada located?
About 95% of all registered EVs in Canada can be found in Quebec, Ontario and British Columbia. Most EVs in Canada are located in regions with current or previous incentive programs. Quebec and British Columbia have rebate programs for purchasing new battery and plug-in hybrid EVs, as well as incentives to install EV chargers. Ontario offered up to $14 000 depending on battery size, number of seats, and cost until July 11, 2018 when the program was cancelled. In addition to cash rebates, Quebec has a ZEV mandate which requires automakers to meet annually increasing ZEV sales targets. Quebec has a target of 100 000 sales by 2020, which equates to roughly 5% of total light-duty vehicle sales.
The pie graph map below shows the estimated number of EVs by propulsion type in each province and territory. The size of the pie and the purple shading is proportional to the number of EVs in that region. You can zoom-in to view the map details. Under “propulsion type”, you can also check the “ICE” box to see the number of EVs in relation to all vehicles.
Source and Description
Description: This map of Canada shows the cumulative number of electric vehicle sales by province and territory, from 2011 to Q2 2017. The number of BEVs and PHEVs per province, starting with the highest numbers, are Quebec (12 465 BEVs, 15 441 PHEVs), Ontario (13 049 BEVs, 13 094 PHEVs), British Columbia (8 102 BEVs, 4 485 PHEVs), Alberta (760 BEVs, 790 PHEVs), Manitoba (135 BEVs, 168 PHEVs), Nova Scotia (87 BEVs, 82 PHEVs), New Brunswick (BEVs 41, PHEVs 115), Saskatchewan (BEVs 62, PHEVs 82), Newfoundland and Labrador (BEVs 12, PHEVs 23), Prince Edward Island (BEVs 16, PHEVs 9), Northwest Territories (BEVs 4, PHEVs 2), Yukon (BEVs 2), Nunavut (PHEVs 1).
Appendix: Calculation Methods
The CO2 emissions of EVs and PHEVs (which are modeled as running on electricity only) can be calculated by multiplying the carbon intensity of electricity generation by the wall-to-wheel efficiency of the vehicle, as shown below:
The carbon-intensity of electricity is the rate at which CO2 is released per unit of electricity generated, and can be expressed in grams of CO2 per kW.h (g CO2/kW.h). These calculations use Canada’s National Inventory Report to the UNFCCC data on emissions and carbon-intensities. Consumption intensities were used because they include line losses and other inefficiencies in delivering electricity to the user’s plug-in.
Wall-to-wheel efficiency, which can be expressed in kilowatt hours per km (kW.h/km), refers to the amount of energy required to drive a vehicle per unit of distance at a certain speed. This includes energy losses while converting electricity into battery charge, and the loss of converting energy in the battery into distance traveled. These calculations assume a mix of 55% city, 45% highway driving. This data is from Natural Resources Canada.
If an electric vehicle was charged using grid electricity, the emissions rate (in g CO2/km) is calculated by multiplying the wall-to-wheel efficiency of the vehicle (in kW.h/km) by the carbon intensity of the local electrical grid (in g CO2/kW.h).
For gasoline powered vehicles (conventional internal combustion engines and hybrid), only CO2 emissions are shown. CO2 makes up 95% to 99% of total vehicle GHG emissions. The remaining emissions, comprised of methane, nitrogen dioxide, and hydrofluorocarbons, are not shown. Gasoline vehicle emissions rates are based on the Natural Resources Canada formula and assumes 2.29 kg of CO2 released per litre burned.
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