Electric VS Fossil Fuel Cars - G4 Physics
- Gabriela Bakun
- Jun 2, 2023
- 6 min read
Which cars emit more pollution considering how the energy in them is produced?
Cars powered by renewable energy sources such as wind, photovoltaic systems and solar energies
There is no getting around the fact that in today’s world, more and more air pollution is created. According to scientists this trend is forecasted to continue rising and will result in 2040 the greatest share of CO2 emissions. Then, changing this path down is a key major universal challenge. Were it not for cars powered by renewable energy sources, the production of pollution would be supposedly much higher. That’s why many countries rely much more on them.
A great example is Canada, where 79% of electricity is generated from renewables like hydro, and nuclear, representing one of the highest percentages in the world, ranking Canada a worldwide leader in clean transport. Compared to the U.S. and China, non-GHG-emitting sources provide less than one-third and one-fifth, respectively.
That’s why, I would like to present the differences between Canada - a leader in clean transport and Italy - an average developed in transport’s renewable energy sources country, and show how much pollution they emit considering the energy produced.
Figure 1. The energy produced from (a) Wind farms; and (b) Photovoltaic systems for Canada and Italy.
Figure 2. Emissions of CO2 spared replacing the vehicle fleet using wind farms for Canada and Italy. [NVFCanada and NVFItaly—the number of cars in circulation in Canada and Italy in 2014]
It can be clearly seen that Canada, as it produces more energy from wind which can be transmitted to transport spare more emission of CO2.
Figure 3: Emissions of CO2 spared replacing the motorcycles/mopeds park using renewable energy for (a) Canada; and (b) Italy.
As can be seen with the rise of renewable energy usage is proportional to the spared emissions of CO2. it is clearly shown that the distribution of Renewable Energy Sources (RES), electric vehicles (EVs) and electric motorcycles (EMs) can operate as a great opportunity for both the environment and the capacities and needs of energy production.
2. Cars powered by lithium ion batteries
Lithium-ion batteries are a type of rechargeable energy storage device that utilizes the movement of lithium ions between two electrodes to store and release electrical energy. They are widely used in portable electronic devices, electric vehicles, and renewable energy systems. The environmental impact of electric vehicles (EVs) compared to gasoline cars is a complex issue that depends on various factors. While the manufacturing of lithium-ion batteries does have some environmental impact, studies generally indicate that EVs have lower overall emissions and are less harmful to the climate compared to traditional gasoline cars1.
Battery manufacturing does contribute to the carbon footprint of EVs, primarily due to the energy-intensive processes involved in extracting and processing raw materials, such as lithium, cobalt, and nickel. Additionally, the production of battery cells and the assembly of battery packs require energy and resources. However, it's important to consider the full life cycle of both EVs and gasoline cars when assessing their environmental impact (Figure 1). The emissions from gasoline cars come from the burning of fossil fuels during both vehicle operation and the extraction, refining, and transportation of gasoline. EVs, on the other hand, produce zero tailpipe emissions during operation since they run on electricity. Studies have shown that, taking into account the emissions from battery manufacturing and electricity generation, EVs have lower lifetime emissions compared to gasoline cars. The exact emissions reduction depends on factors like the energy mix of the grid and the driving patterns of the vehicle owner3. Moreover, ongoing advancements in battery technology and manufacturing processes aim to reduce the environmental impact of lithium-ion batteries further.
In summary, while the manufacturing of lithium-ion batteries for EVs does have an environmental impact, studies indicate that the lower emissions during operation and the overall energy efficiency of EVs make them better for the climate compared to gasoline cars. Transitioning to renewable energy sources for electricity generation further enhances the environmental benefits of electric vehicles.
Figure 1: Estimates shown from GREET 2 2021
3. Traditional cars
Traditional cars use gasoline or diesel to fuel their engines. Burning these fuels can have an enormous impact on one’s health and the environment, as they emit harmful pollutants. For example, gasoline fumes can even escape into the air while pumping gas into fuel tanks.
Passenger vehicles are a major contributor to air pollution. Whether the car is burning gasoline or diesel, the byproducts from this process contribute to harmful emissions found in our atmosphere such as nitrogen dioxide, carbon monoxide, hydrocarbons, benzene, and formaldehyde. In addition, vehicles emit carbon dioxide, the most common human-caused greenhouse gas.These emissions create a chemical imbalance in the atmosphere and so makes the air we breath and need for life extremely polluted.
The burning of gasoline and diesel therefore contributes to production of ground-level ozone which damages crops, trees and other vegetation. Also produced is acid rain, which affects soil, lakes and streams and enters the human food chain via water, produce, meat and fish. Apart from that, there has been an increase in respiratory health problems, which are directly a cause of air pollution, such as asthma, lung diseases and heart problems.
Figure: 3 The chart shows how different passenger cars produce different quantities of CO2 emissions.
In summary, the burning of fuels such as gasoline and diesel in cars causes the degradation of the environment due to pollutants being released into the air. These harmful chemicals damage vital ecosystems such as plants, trees and even our water systems, which we heavily rely on.
Which type of vehicle is more efficient?
You might have heard that the major advantage of electric cars over fossil fuels is their greater efficiency. According to the research conducted at the University of Tianjin by Liu Haifeng and his team, the thermal efficiency of gasoline engines is between 30% and 36%. It means that for every 1 liter of fuel bought, only about 0.3 liters of it is converted to move your car. But why exactly is that the case? The answer lies in the consequences of the laws of thermodynamics.
Cars that use fossil fuels operate on internal combustion engines. In those engines, mechanical energy is produced by burning a mixture of oxygen and fuel according to the engine cycle.
Source: Own work based on engineeringlearn.com.
Knowing that the first law of thermodynamics states that energy can neither be created nor destroyed, only transferred, you might wonder why not all the energy produced from combustion is turned into mechanical energy.
The energy can also change its form. As seen in the diagram below the outputs are not restricted to heat, mechanical work, and combustion products as it would be expected.
Source: x-engineer.org.
Now that we established what happens, we will look closer at why it happens. According to The Carnot Limit, there is a certain restriction to the mechanical energy that can be produced from the fuel. As the second law of thermodynamics states, heat moves from hotter objects to colder objects. If there is a big difference in temperature between fuel combustion, the engine, and the air outside, the efficiency will be low. It happens because the energy is used to heat the engine and air outside, as their temperature is much lower than that of the fuel combustion.
Source: Own based on Haifeng (2018). The lowest values in the range were used.
On the other hand, electric vehicles, according to the Department of Energy, electric engines transform over 85 percent of electrical energy into mechanical energy that drives your car. It happens because the electric motor directly converts the energy into movement instead of burning the fuel first. The efficiency still depends on the charging conditions and battery efficiency - how much energy is delivered to the engine. The efficiency can be measured by looking at the car’s average speed, energy recovery, and the number of kilometers that the car can be driven on a single charge. By looking at those values it was observed that it was much greater than for combustion engines.
Additionally, there are several methods being implemented in new cars that improve the efficiency of electric motors. They include the use of better materials and increasing airflow. Those improvements aim to reduce the energy loss caused by friction and production of heat, that occurs in combustion engines.
You can notice that electric cars are not only a better option for the environment but also for your wallet. If the efficiency is higher, less energy you bought is lost, so you save more money.
https://engineeringlearn.com/how-does-4-stroke-engine-works/
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https://carorbis.com/blog/difference-between-petrol-engine-and-diesel-engine-explained/
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