What is the carbon footprint of a conventional car?
Summary
On average, a combustion engine car emits around 4.6 tonnes of CO2 per year, and understanding the carbon footprint of a combustion engine vehicle is essential to assess its environmental impact. In this article, discover the factors influencing these emissions, how to calculate the carbon footprint of a combustion engine car and tips for reducing it.
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Understanding the carbon footprint of internal combustion vehicles
The carbon footprint of an internal combustion vehicle is the total amount of carbon dioxide (CO2) and other greenhouse gases emitted throughout its life cycle. This includes direct emissions from fuel combustion while driving, as well as indirect emissions from fuel production, transportation and refining. Emissions generated during the vehicle’s manufacturing process and those produced during its maintenance and end-of-life are also taken into account.
Factors influencing the carbon footprint of an internal combustion vehicle
Fuel type
The type of fuel used by an internal combustion vehicle has a significant impact on its carbon footprint. Petrol generally produces more CO2 per litre consumed compared to diesel, but diesel emits more fine particles and nitrogen oxides (NOx), which are harmful to health.
Alternative fuels such as biofuels or synthetic fuels can reduce CO2 emissions, although their production and availability are still limited. The choice of fuel directly influences the overall carbon footprint of the vehicle.
Fuel consumption
Fuel consumption depends on several elements, such as the size and weight of the vehicle, the efficiency of the engine, and driving style. Heavier and less aerodynamic cars generally consume more fuel, thus increasing their CO2 emissions. Aggressive driving, with frequent acceleration and braking, can also increase fuel consumption. Finally, regular maintenance can improve the fuel efficiency of a vehicle, thus reducing its overall carbon footprint.
Vehicle life cycle
The carbon footprint of a combustion engine car is not limited to its use, but also includes its entire life cycle. This starts with the emissions related to the extraction of raw materials and the manufacturing of the vehicle components. Then, the production and assembly of the car also contribute to emissions. During the use phase, emissions mainly come from fuel combustion. Finally, the end of life of the vehicle, with recycling and waste management, generates additional emissions. A life cycle analysis (LCA) makes it possible to quantify these impacts at each stage, providing a global vision of the carbon footprint.
How to calculate a car’s CO2 emissions?
Calculating a car’s CO₂ emissions is a key step in understanding its environmental impact and identifying ways to reduce them. This calculation is based on several methods, taking into account not only fuel consumption but also the entire life cycle of the vehicle.
Using emission factors
Emission factors are coefficients that convert the amount of fuel consumed into CO₂ emissions. They are provided by reference organizations such as ADEME or the GHG Protocol.
These factors vary depending on the type of fuel used:
- Petrol: approximately 2.31 kg of CO₂ emitted per liter consumed.
- Diesel: approximately 2.68 kg of CO₂ per liter.
- LPG (Liquefied Petroleum Gas): approximately 1.66 kg of CO₂ per liter.
These factors generally include direct emissions related to fuel combustion, but in some cases, extended emission factors may also include emissions related to fuel production and transportation (upstream emissions).
Calculation based on fuel consumption
To calculate the annual CO₂ emissions of a combustion vehicle, the basic formula is as follows:
CO₂ emissions (kg) = Annual fuel consumption (litres) × Emission factor (kg CO₂/litre)
Example of a fuel consumption calculation:
If a car consumes 1,200 litres of petrol per year:
1,200 litres × 2.31 kg CO₂/litre = 2.77 tonnes of CO₂ per year.
To refine this calculation, it is also recommended to take into account:
- Actual consumption rather than the manufacturer’s official values, which are often more optimistic.
- Driving style, which can significantly influence consumption (sporty driving increases fuel consumption).
- Type of journey: driving in an urban environment is more fuel-intensive than on the motorway due to frequent stops and slowdowns.
Life Cycle Analysis (LCA)
Life Cycle Analysis (LCA) is a more comprehensive method used to assess the total carbon footprint of a vehicle. It takes into account all stages, from manufacturing to the end of the car’s life, and provides an overall view of the associated CO₂ emissions.
LCA includes:
- Manufacturing phase: Extraction of raw materials (steel, aluminium, plastic), manufacturing of parts and assembly of the vehicle. This phase represents on average 20% to 30% of the total carbon footprint of a thermal car.
- Use phase: The most emitting, representing approximately 60% to 70% of total emissions, particularly due to fuel combustion.
- End-of-life phase: Dismantling, recycling of materials and waste management. Although this step has less impact in terms of CO₂ emissions, it remains important for a complete analysis of a car’s carbon footprint.
Example of LCA for a thermal car over 150,000 km:
Manufacturing: approximately 6 tonnes of CO₂
Use (fuel combustion): approximately 18 tonnes of CO₂
End of life: approximately 1 tonne of CO₂
A total of approximately 25 tonnes of CO₂ over the entire life cycle of the car.
Tools for calculating CO₂ emissions from a car
To simplify the calculation, online calculators are also available. These different tools, offered by platforms such as ADEME or specific applications, make it possible to quickly estimate the CO₂ emissions of a vehicle by entering data such as:
- The car model
- The fuel type
- The average consumption
- The annual mileage
These tools can also integrate extended emission factors to include indirect emissions, thus providing a more precise estimate of the environmental impact of the thermal vehicle.
CO2 Emissions Cars: Integration of indirect emissions
Beyond fuel combustion, it is advisable to take indirect emissions into account when calculating the CO2 emissions of cars, such as:
- Oil extraction and refining: These different energy-intensive processes generate significant emissions even before the fuel is available to individuals.
- Logistics and fuel transport: The transport of fuel from refineries to service stations also contributes to the overall carbon footprint of thermal cars.
- Vehicle maintenance: Replacing parts, changing oil, and even manufacturing tires are also factors in a car’s indirect emissions.
Incorporating these parameters into the calculation provides a more realistic and comprehensive estimate of a thermal car’s CO₂ emissions.
Reducing the carbon footprint of combustion engine cars
Improving energy efficiency
Improving the energy efficiency of combustion engine cars is essential to reducing their carbon footprint. This not only reduces CO₂ emissions, but also saves fuel in the long term.
- Regular maintenance: Keeping the vehicle in good condition, with correctly inflated tires and clean air filters, improves fuel consumption. A well-maintained engine runs more efficiently, reducing energy losses. In addition, regular checks of engine oil levels and braking systems help to optimize vehicle performance.
- Using innovative technologies: The integration of modern engine management systems and particle filters also significantly reduces pollutant emissions. In addition, technologies such as stop & start (which automatically switches off the engine when stationary) or optimized automatic transmissions improve energy efficiency by adapting consumption to driving.
- Eco-responsible driving: Adopting a smooth driving style and avoiding sudden acceleration and braking also helps save fuel. Maintaining a stable speed and using the engine brake when decelerating are simple practices that reduce fuel consumption. In addition, anticipating traffic and avoiding unnecessary idling helps limit unnecessary emissions.
- Reducing vehicle weight: Using lightweight materials, such as aluminum or composites, can significantly improve fuel efficiency by reducing the load to be moved. Avoiding carrying unnecessary loads in the trunk or on the roof also limits fuel consumption. Finally, lightweight rims or thinner windows can contribute to a gain in performance without compromising vehicle safety.
Alternatives to reduce the carbon footprint
To reduce the carbon footprint of thermal cars, several alternatives can be adopted:
- Alternative fuels: Using biofuels or synthetic fuels reduces CO₂ emissions compared to traditional fossil fuels. These fuels, derived from organic materials or more sustainable chemical processes, help reduce the vehicle’s overall carbon footprint. In addition, these alternative fuels can often be used in existing engines with few modifications, which facilitates their large-scale adoption.
- Opt for hybrid vehicles: Hybrid vehicles combine a thermal engine and an electric motor to improve energy efficiency and reduce fuel consumption. This technology helps limit CO₂ emissions, particularly in urban areas, where the electric motor takes over during low-speed phases. In addition, hybrid cars offer greater autonomy than 100% electric vehicles, while maintaining lower costs.
- Switch to electric vehicles: Electric vehicles do not emit CO₂ during use, making them a key solution for reducing the environmental impact of transport. They are significantly more energy efficient than combustion engines, and are particularly advantageous when electricity comes from renewable sources. In addition, maintenance costs are generally lower, as they have fewer mechanical parts subject to wear.
- Soft mobility: Encouraging the use of public transport, carpooling, cycling and walking is an excellent way to reduce the carbon footprint in everyday life. These modes of transport limit greenhouse gas emissions while promoting better air quality in urban areas. In addition, soft mobility helps to relieve road congestion, reduce noise pollution and promote a healthier lifestyle for individuals.
CO2 emissions cars: thermal car vs electric car
The average carbon footprint of a thermal car and an electric car can vary depending on several factors such as the model, use, and the source of electricity for electric vehicles.
Thermal car
Average annual carbon footprint: Around 4.6 tons of CO2 per year.
Total life cycle: Around 24 tons of CO2 for a car traveling 150,000 km (including manufacturing, use and end of life).
Electric car
Average annual carbon footprint: Around 1.5 tons of CO2 per year (this figure can vary widely depending on the source of electricity used).
Total life cycle: Around 12 tons of CO2 for a car traveling 150,000 km (including manufacturing, including batteries, use and end of life).
Electric cars have a higher initial carbon footprint due to the production of batteries. However, they compensate for this carbon footprint, through cleaner use. Thermal cars, on the other hand, emit CO2 throughout their life, mainly when burning fuel.
The overall carbon footprint of electric cars depends on the source of electricity used: electricity from renewable sources significantly reduces their impact, which is not the case if the source is not renewable. So in general, electric cars tend to have a lower carbon footprint over their life cycle compared to thermal cars.
The carbon footprint of a thermal car depends on many factors, including the type of fuel, consumption and the life cycle of the vehicle. By improving energy efficiency and adopting alternatives such as hybrid or electric vehicles, it is possible to significantly reduce these emissions and contribute to a more sustainable future.
