Electric car emissions using power from the grid in countries with coal based generation are no different to average petrol vehicles, while in countries with low carbon electricity they are less than half those of modern hybrids.
The scale of this variation implies that the climate benefits of going electric are not evenly shared around the globe.
Electric car emissions
It is quite well understood that electric cars have the potential to reduce carbon emissions, but important to realize this potential is dependent on the type of electricity that charges the battery. Given that the vast majority of power generation around the world is grid-tied, where a car is charged plays a large role in determining electric car emissions. In addition, the manufacture of a car contains a hidden productions related carbon emissions.
AFDC calculates averages for car emissions in the U.S.
The Alternate Fuels Data Center which is a division of the Department of Energy in the US government surveys and calculates emissions. They note average electric car emissions are 3932 pounds of CO2 every year. This is averaged over distances, grid sources, car models etc, so is a very rough number. They note also gasoline car emissions are 11,435 pounds of CO2 per year. Therefore gas cars emit 2.9 times more carbon than electric cars, for the US and averaged over grid sources in different states.
Similarly, here by considering the full scope of emissions that occur in both electricity supply and vehicle manufacturing we compare the carbon emissions of electric cars in twenty of the world’s leading countries. Gasoline and petrol cars have carbon emission ratings as well, as we cover elsewhere.
Electric car emissions can be four times greater in places with coal dominated generation than in those with low carbon power.
The legend to the right of this chart helps explain what is driving the variation between countries. All the difference between Paraguay and India is a result of changes in the fuel mix, from low carbon hydro at the bottom to high carbon coal at the top.
In the United States, the average emissions of an electric car is 202 g CO2e/km. Is this good? Well, sure, it’s better than a gasoline or petrol car in the same country, but worse than electric cars in other countries which get their electricity from lower carbon sources.
Hydroelectric powerhouse Paraguay comes out on top. There the carbon emissions of electric cars are 70 g CO2e/km, inclusive of vehicle manufacturing, and electric driving, which is significantly lower than using solar power.
In contrast, in India, Australia and China, the dominance of coal in the fuel mix means that grid powered electric cars produce emissions ranging from 258g CO2e/km to 370 g CO2e/km, many multiples of those using low carbon sources.
Comparing Electric Emissions to Gasoline and Petrol Cars
Electric cars’ carbon emissions can vary from similar to average petrol cars to less than half those of the best petrol hybrids. We show this by first accounting for the difference in vehicle manufacturing emissions and then calculating the equivalent petrol vehicle emissions in terms of fuel economy, MPGUS. Presented in this way the results are more intuitive, allowing us to compare electric car emissions with conventional vehicles in a more familiar metric.
The legend to the right gives a rough idea of which petrol vehicle, if any, has carbon emissions comparable to an electric vehicle in each country.
In Paraguay electric cars results in carbon emissions equivalent to a 218 MPGUS (1 L/100 km) petrol vehicle. Contrast this with India where a full electric vehicle causes emissions comparable to a 20 MPGUS (12 L/100 km) petrol car. In China the figure is 30 MPGUS (9 L/100 km).
Based on data from 2009 the US petrol emissions equivalence is 40 MPGUS (9 L/100 km), similar to a modern petrol hybrid. But at the speed US electricity is decarbonizing this figure is rising quickly.
In the UK, Germany, Japan and Italy the broad fuel mix of natural gas, coal, nuclear and hydro means an electric vehicle’s carbon footprint is similar to the best comparable petrol hybrid, or most efficient diesel. In the UK this equals a petrol fuel economy of 44 MPGUS (5.4 L/100 km), while in Germany it rises to 47 MPGUS (5.0 L/100 km)
In Canada and France, where hydroelectricity and nuclear energy dominate, the petrol emission equivalences are 87 MPGUS (2.7 L/100 km) and 123 MPGUS (1.9 L/100 km) respectively. In these countries electric cars have the potential to more than halve total vehicle emissions.
Manufacturing Emissions Matter
As vehicles become increasing low carbon manufacturing emissions matter more and more.
Our central scenario for vehicle manufacturing was 70 g CO2e/km for an electric vehicle and 40 g CO2e/km for a petrol car. As explained in the report these estimates were made using the best available literature.
To highlight how important these assumptions are for low carbon vehicles we ran a crude sensitivity test by holding petrol manufacturing emissions constant while estimating a low (50 g CO2e/km) and high (90 g CO2e/km) scenario for electric vehicle manufacturing.
The results show that manufacturing emissions become increasingly important as electricity moves to low carbon sources.
At the bottom of the graph we can see that changing the manufacturing emissions assumptions does little to affect the equivalent emissions fuel economy. But as we reach countries like the US, UK and Germany the difference become significant. Finally at the top of the chart it has a very large effect.
Although we believe our central estimate of 70 g CO2e/km for electric vehicle manufacturing is a reasonable one, the more important point is to stress that in low carbon vehicles, whether hybrid, diesel, plug-in or full electric, manufacturing emissions are an important share of total emissions.
I founded Shrink That Footprint in November 2012, after a long period of research. For many years I have calculated, studied and worked with carbon footprints, and Shrink That Footprint is that interest come to life.
I have an Economics degree from UCL, have previously worked as an energy efficiency analyst at BNEF and continue to work as a strategy consultant at Maneas. I have consulted to numerous clients in energy and finance, as well as the World Economic Forum.
When I’m not crunching carbon footprints you’ll often find me helping my two year old son tend to the tomatoes, salad and peppers growing in our upcycled greenhouse.