Compare The CO2 Emissions Of A Hybrid Vehicle To Those Of A

Compare the CO2 emissions of a hybrid vehicle to those of a plug-in electric vehicle

Last year I needed to buy a new car and decided to get a hybrid – specifically a 2019 hybrid Toyota Avalon. It runs on gasoline, but also has a battery and electric motor that extends its driving range on a gallon of gasoline. It gets more than double the MPG that my old Lexus achieved. I also considered buying a plug-in electric vehicle, such as a Tesla Model Y. In this assignment, I will compare the environmental impact of operating a hybrid vehicle like my Avalon with that of a plug-in electric vehicle like a Tesla Model Y.

This comparison considers several factors, primarily focusing on carbon dioxide (CO2) emissions, but also including other emissions relevant to environmental impact. The analysis takes into account the specifics of the driving conditions—10,000 miles per month in Tucson, Arizona—and the electricity generation profile of Tucson Electric Power (TEP). While it seems obvious that electric vehicles (EVs) have no tailpipe emissions, it is crucial to account for the emissions produced during electricity generation when charging EVs. Conversely, hybrid vehicles produce emissions directly through combustion, alongside emissions associated with fuel production. The goal is to evaluate which vehicle presents a lower environmental impact in terms of overall emissions, considering their lifecycle and operational emissions.

Comparing CO2 Emissions of Hybrid and Electric Vehicles

The primary difference between hybrid and fully electric vehicles lies in their modes of power generation. Hybrids like the Toyota Avalon consume gasoline and emit CO2 directly through combustion, but benefit from increased fuel efficiency, leading to lower emissions per mile compared to traditional gasoline-only vehicles. Conversely, Tesla Model Y operates entirely on electricity, thus producing zero tailpipe emissions. However, its overall emissions depend heavily on the cleanliness of the electricity grid used for charging.

To quantify CO2 emissions, I first assessed the fuel consumption of the hybrid Toyota Avalon. The Avalon’s average fuel efficiency is approximately 39 miles per gallon (EPA, 2020). Operating 10,000 miles per month equates to roughly 256 gallons of gasoline consumed monthly (10,000 miles / 39 MPG). Given that burning one gallon of gasoline produces about 8.89 kg of CO2 (EPA, 2020), the Avalon emits approximately 2,278 kg of CO2 per month (256 gallons x 8.89 kg). Over a year, this amounts to approximately 27,336 kg of CO2 (12 months).

In contrast, the Tesla Model Y consumes electricity instead of gasoline. Its energy consumption is roughly 28 kWh per 100 miles (Tesla, 2023). Driving 10,000 miles per month requires about 2,800 kWh (10,000 miles / 100 miles x 28 kWh). In Tucson, the electricity grid’s emission factor is approximately 0.54 pounds of CO2 per kWh (U.S. EPA, 2022), which converts to about 0.244 kg per kWh. Therefore, the monthly emissions from electricity used to charge the Tesla are around 683 kg (2,800 kWh x 0.244 kg), totaling approximately 8,200 kg annually (12 months). This indicates that, based on electricity emissions alone, the Tesla contributes significantly less CO2 emissions during operation compared to the hybrid Avalon.

Other Emissions from Hybrid and Electric Vehicles

While CO2 is a primary concern due to its impact on climate change, other emissions also pose health and environmental risks. Hybrid vehicles emit pollutants such as nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), and volatile organic compounds (VOCs) during combustion. These emissions contribute to smog formation, respiratory problems, and environmental degradation. According to the EPA (2020), gasoline vehicles emit NOx at levels that can cause smog and acid rain formation.

Electric vehicles, on the other hand, produce no tailpipe emissions, thus eliminating direct emissions of pollutants like NOx, CO, and PM. However, upstream emissions from electricity generation can include pollutants depending on the energy mix. In Tucson, since a significant portion of electricity still comes from fossil fuel sources (coal and natural gas), EVs indirectly contribute to emissions of NOx, SOx, PM, and other pollutants emitted during power plant operation (U.S. EPA, 2022). Transitioning to cleaner energy sources would further reduce these emissions, making EVs more environmentally advantageous over time.

The Overall Environmental Impact of Hybrid vs. Electric Vehicles

When comparing the environmental impacts, several factors emerge. The hybrid Toyota Avalon, while more fuel-efficient than traditional gasoline vehicles, still relies on fossil fuels and produces direct CO2 and pollutant emissions during operation. Its annual CO2 emissions in this scenario amount to approximately 27,336 kg, with significant contributions from tailpipe pollutants contributing to smog and health issues.

The Tesla Model Y, operating on electricity with emissions of roughly 8,200 kg CO2 annually in Tucson, produces no tailpipe emissions, reducing local air quality issues. Its greater environmental benefit depends heavily on the electricity grid’s energy mix. In regions with cleaner grids—such as areas largely powered by renewables—EVs could have substantially lower overall emissions (Breetz et al., 2018). Investments in renewable energy and grid decarbonization are crucial for maximizing the environmental benefits of electric vehicles.

Furthermore, electric vehicles have an advantage in lifecycle emissions, as manufacturing batteries can be energy-intensive, but improvements in manufacturing efficiency and battery technology are reducing these impacts (Ellingsen et al., 2016). Over its lifespan, an EV may offset its higher manufacturing emissions through lower operational emissions, especially if charged from renewable sources. Conversely, hybrid vehicles strike a balance, reducing emissions relative to traditional vehicles but still limited by reliance on fossil fuels.

In conclusion, the overall environmental impact of a Tesla Model Y is likely lower than that of a hybrid Avalon, primarily when electricity generation is increasingly based on renewable sources. As electricity grids become cleaner, electric vehicles will become the more sustainable choice, whereas hybrids may continue to serve as effective transitional technologies. Effective policy measures aimed at expanding renewable energy and incentivizing electric vehicle adoption are vital to achieving significant reductions in transportation-related emissions.

References

  • EPA. (2020). Greenhouse Gas Emissions from a Typical Passenger Vehicle. United States Environmental Protection Agency. https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle
  • Tesla. (2023). Tesla Model Y Energy Consumption and Range. Tesla Inc. https://www.tesla.com/models
  • U.S. EPA. (2022). Greenhouse Gas Equivalencies Calculator. United States Environmental Protection Agency. https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator
  • Breetz, H. L., Meckling, J., & Sadownik, N. (2018). The politics of electric vehicle adoption: Beyond consumer preferences. Environmental Politics, 27(3), 375-394.
  • Ellingsen, L. A.-W., Majeau-Bettez, G., Singh, B., et al. (2016). Life cycle assessment of a lithium-ion battery vehicle propulsion system. Environmental Science & Technology, 50(17), 8794–8804.
  • Union of Concerned Scientists. (2021). Electric Vehicle Benefits. https://www.ucsusa.org/resources/electric-vehicles
  • International Energy Agency. (2022). Global EV Outlook 2022. IEA Publications.
  • Faria, R., Moura, P., Delgado, J., & de Almeida, A. T. (2013). A sustainability assessment of electric vehicles considering energy sources and recycling. Energy Policy, 57, 234-242.
  • Hawkins, T. R., Singh, B., Majeau-Bettez, G., & Strømman, A. H. (2013). Comparative environmental life cycle assessment of conventional and electric vehicles. Journal of Industrial Ecology, 17(1), 53–64.
  • Sharma, A., & Khare, S. (2020). Environmental implications of electric vehicles: An overview. Sustainable Energy Technologies and Assessments, 42, 100829.

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