Comparison of carbon emissions: Electric cars vs. Petrol-powered cars
Check out this answer from Consensus:
Electric vehicles have the potential to significantly reduce carbon emissions compared to petrol-powered cars, particularly when charged with electricity from renewable sources. However, the environmental benefits of EVs are contingent on various factors, including the source of electricity, regional variations, and advancements in battery production and recycling technologies. Policymakers and consumers must consider these factors to maximize the environmental benefits of transitioning to electric vehicles.
The transition from petrol-powered cars to electric vehicles (EVs) is often touted as a significant step towards reducing carbon emissions and combating climate change. However, the environmental benefits of EVs depend on various factors, including the source of electricity used for charging and the lifecycle emissions of the vehicles. This article explores how the carbon emissions of electric cars compare to those of petrol-powered cars, drawing on recent research findings.
Lifecycle Carbon Emissions
Lifecycle assessments (LCA) provide a comprehensive view of the carbon emissions associated with both electric and petrol-powered cars. These assessments consider emissions from the production, use, and disposal phases of the vehicles.
Production Phase
The production of electric vehicles, particularly the manufacturing of batteries, is energy-intensive and can result in significant carbon emissions. For instance, producing batteries with photovoltaic electricity instead of Chinese coal-based electricity can decrease the climate impacts of battery production by 69%1. However, the initial carbon footprint of manufacturing an electric vehicle is generally higher than that of a petrol-powered car due to the energy required to produce the batteries4.
Use Phase
During the use phase, electric vehicles typically produce lower carbon emissions compared to petrol-powered cars, especially when charged with electricity from renewable sources. For example, the CO2 emissions from an electric vehicle can be 4.6 times lower than those from a diesel vehicle under certain conditions2. Additionally, electric vehicles charged with electricity from low-carbon sources such as wind or solar power can significantly reduce their overall carbon footprint4 5.
Disposal Phase
The disposal phase of electric vehicles, particularly the recycling of batteries, also contributes to their overall carbon emissions. However, advancements in battery recycling technologies are expected to mitigate these emissions over time3.
Real-World Driving Conditions
Real-world driving conditions can influence the carbon emissions of both electric and petrol-powered cars. Studies have shown that electric vehicles can compete well in terms of CO2 emissions per passenger kilometer with other modes of transport, such as diesel buses and trains, especially when optimized conditions are met1. In contrast, petrol-powered cars generally exhibit higher emissions due to the combustion of fossil fuels7.
Regional Variations
The carbon emissions of electric vehicles can vary significantly depending on the regional electricity mix. In regions where electricity is primarily generated from fossil fuels, the carbon emissions of electric vehicles may be comparable to or even higher than those of petrol-powered cars6 7. For instance, in Poland, where coal is a major source of electricity, the indirect emissions from electric cars can be higher than the direct emissions from petrol-powered cars7.
Comparative Studies
Several comparative studies have highlighted the potential of electric vehicles to reduce carbon emissions under specific conditions:
- A study comparing the cumulative CO2 emissions of electric and combustion cars found that electric cars result in lower cumulative CO2 emissions when charged with electricity from renewable sources4.
- Another study indicated that electric vehicles could contribute to a reduction in petroleum dependence and air quality improvement, provided that the electricity sector undergoes significant decarbonization9.
- Research comparing different powertrain passenger cars showed that battery electric vehicles (BEVs) have lower greenhouse gas emissions but higher freshwater eutrophication and ecotoxicity impacts compared to internal combustion and hybrid powertrains3.
Does a Tesla Emit More Carbon Emissions Than a Petrol-Powered Toyota Corolla or Mitsubishi Mirage?
Elliott Campbell has answered Unlikely
An expert from University of California, Santa Cruz in Environmental Science
If you live in the United States, your transportation choices might be the single most important issue for your overall carbon emissions. See for yourself with a personal carbon footprint tool like the CoolClimate Calculator.
Reducing personal vehicle miles is critical. But if you do need a ride, thankfully the U.S. EPA regularly conducts laboratory tests on new vehicles to make your choice easier. You can browse their user-friendly ratings at fueleconomy.gov. Comparing a full-size Tesla to a sub-compact Mirage is strange so it might make more sense to start by comparing the Mirage to a reasonably priced plug-in hybrid.
Take for example, the plug-in hybrid version of the Hyundai Ioniq. The Ioniq can be plugged in for up to 29 miles of electric-only range and has a gasoline engine that kicks in to get you the rest of the way so that arriving at your destination is never a problem. The Ioniq’s relatively small battery means you are driving on gasoline some of the time, but the EPA ratings still show that the Ioniq is a very strong environmental performer. The Ioniq’s carbon footprint is 30% smaller than the Mirage for the average of all U.S. electricity sources and only half the footprint of the Mirage in my hometown of Santa Cruz where renewables are more abundant. So when it comes to carbon, a little battery goes a long way. Even in regions where electricity is made in coal power plants with high CO2 emissions the Ioniq is still way ahead (e.g. West Virginia the Ioniq is 27% lower).
What is the EPA rating in your hometown? Find out at fueleconomy.gov. But what about vehicles with exceptionally large batteries like the Tesla? The EPA ratings account for tailpipe and power plant emissions but they don’t currently account for pollution from making the battery. Battery footprints are an important ongoing area of research. New science that also accounts for the battery production shows that the Tesla Model S outperforms the Mirage for the average U.S. electricity mix and has only somewhat higher emissions in regions that rely more heavily on coal. This is impressive given the apples to oranges comparison between a full-sized luxury car and a sub-compact. Some fun interactive visuals from this study are here, carboncounter.com.
But what about in Australia where nearly 80% of electricity comes from coal? The MP says that a Tesla is worse than a Mirage and he is only partly correct. The sub-compact Mirage does comes out ahead of the Tesla Model X, a 7-seater luxury SUV that accelerates to 60 mph in under 3 seconds. But, even with this apples to oranges comparison, the Model X will outperform the Mirage in regions of Australia that have electricity emissions similar to the United States.
So does the Tesla emit more than the Mirage? In the U.S. the answer is “unlikely” because for most of the U.S. the electricity is clean enough for the Tesla to be the winner. In Australia the opposite is true. Some of the vehicles with smaller batteries, like the plug-in hybrid Ioniq, will always top the Mirage. And so will your bike.
Does a Tesla Emit More Carbon Emissions Than a Petrol-Powered Toyota Corolla or Mitsubishi Mirage?
Kevin Gurney has answered Unlikely
An expert from Arizona State University in Atmospheric Science, Environmental Science
A Tesla and all electric vehicles can be assumed to be drawing their power from a local electrical grid (in some cases from residential solar systems, but let’s leave that aside for the moment). Calculations have been performed that consider the power production mix in each portion of the United States that cast the carbon footprint of the electricity consumed to the equivalent MPG of a conventional gasoline powered internal combustion engine. In most regions, the electricity (and the electric vehicle using that electricity) is very close to, or much less, than the stated Mitsubishi Mirage MPG of ~40 MPG. For example, the region of the US that includes Colorado, Nebraska, Illiinois, Indiana, Oklahoma, Michigan and parts of Wyoming and Texas have equivalent MPG’s of electricity that are in the range of 35-38 MPG. All other regions of the country have equivalent MPG values that exceed 40 MPG reaching as high as 135 MPG (New York). Hence, it is unlikely that a Tesla emits more carbon per unit mile driven than a mitsubishi Mirage. Of course that is for the “use” portion of the vehicle. There is also manufacturing to consider, but I will leave that for another time.
Does a Tesla Emit More Carbon Emissions Than a Petrol-Powered Toyota Corolla or Mitsubishi Mirage?
Chris Frey has answered Unlikely
An expert from North Carolina State University in Civil Engineering, Environmental Science
The answer is: “it depends”. This website allows comparison of specific vehicles with respect to CO2 emissions and other metrics of interest: https://www.afdc.energy.gov/calc/ I ran it for: 2017 Mitsubishi Mirage G4 Gasoline 2017 Tesla Model S AWD – P100D EV The Mirage fuel economy is rated at 35/42 mpg city/hwy. For typical driving conditions, and 11926 miles per year of driving, the Mirage will emit 7400 lbs of CO2 per year, based on 309 gallons per year of fuel consumed. There can be variability in these numbers depending on driving habits, mileage accumulation, vehicle maintenance, terrain, climate, etc. However, it is fairly common that gasoline vehicles emit more than their weight in CO2 emissions each year. The Tesla is rated at 36/32 kWh/100 miles for city/hwy driving. Based on a typical mix of city and hwy driving, the Tesla would consume approximately 4,028 kWh of electricity per year. The CO2 emissions for the Tesla will depend on the fuel mix for electric power. The web site allows users to select a U.S. state and estimates CO2 emissions based on the power generation fuel mix for that state. There are some caveats to this. One is that electricity is transmitted across state lines; thus, the power mix within a state is not necessarily the power mix of the electricity consumed at the outlet. Another is that the power mix varies with time of day. Vehicles charged overnight are more likely to be charged by baseload coal, nuclear, and hydro, whereas vehicles charged during the day might be more likely to be charged using intermediate or peaking load natural gas-fired gas turbines. However, the estimates below are a reasonable indication of averages. The energy consumption of the Tesla will also depend on driving habits, climate, terrain, etc.. Thus, actual energy consumption and emissions may vary. The CO2 emissions for the Tesla are estimated to be: Alabama: 4,500 lbs CO2 California: 2,400 lbs CO2 Florida: 5,100 lbs CO2 Kentucky: 9,300 lbs CO2 Illinois: 3,800 lbs CO2 Maryland 4,600 lbs CO2 New York 2,200 lbs CO2 North Carolina: 4,500 lbs CO2 Vermont: 9 lbs CO2 (this is not a typo – the electricity mix in Vermont is hydro and renewable sources). West Virginia: 10,100 lbs CO2 (the energy mix is mostly coal) (you can use the website above to try other states). Thus, despite potential sources of variation in these estimates, it is clear that the Tesla can have much lower CO2 emissions than the much smaller Mirage, unless one lives in a region with coal intensive power generation such as Kentucky or West Virginia.
Does a Tesla Emit More Carbon Emissions Than a Petrol-Powered Toyota Corolla or Mitsubishi Mirage?
Stefano Caserini has answered Likely
An expert from Politecnico di Milano in Environmental Science, Engineering
This source provides average consumption for Tesla of about 20 kWh/100 km. The CO2 intensity of power generation in Australia is between 0.14 kgCO2eq/kWh (Tasmania) and 1.08 (Victoria) kgCO2eq/kWh, with a reference value of 0.78 kgCO2eq/kWh for the National Electricity Market (table 5 and table 6 here www.environment.gov.au/system/files/resources/5a169bfb-f417-4b00-9b70-6ba328ea8671/files/national-greenhouse-accounts-factors-july-2017.pdf) Thus the emission factor for the Tesla charged in the Australian grid is between 28 gCO2/km and 216 gCO2/km, with an average of 156 gCO2/km. The average consumption for a Mirage it seems about 100 gCO2/km http://www.nextgreencar.com/emissions/make-model/mitsubishi/mirage/ but it is not clear if this is the “real world” emission factor. (caveats: The CO2 intensity of power generation in Australia is provided in CO2eq, but I believe that is not too different from the one in CO2. The life cycle CO2 is not considered, etc) So, my conclusion is that the CO2 emission from the two vehicles are not so different if electricity is produced by dirty fossil fuels.