Gasoline Car Emissions
As we know, burning dead dinos produces some smoke with sorts of nasty stuff in it. Broadly speaking though, the car emissions can be divided into two broad categories: Pollutants and Greenhouse gases.
The pollutants, those are the toxic ones they’re bad for the health of people, animals, and plants. Pollutants include things like airborne particulates, hydrocarbons, oxides of nitrogen (or NOx), sulfur dioxide, and carbon monoxide. In the US and most of the western world, we’ve been cleaning up these emissions for the past 50 years.
The second type of emissions are the greenhouse gases. You may have heard the truth about their inconvenience once or twice, particularly the issues with CO2 emissions, while CO2 isn’t directly harmful to our health. If its atmospheric concentration changes by a lot, this can really affect the global climate, which can negatively impact us and animals, our lives and future lives.
Carbon Emissions of Electric Car Vs Gasoline Car
Carbon Emissions of Electric Car
As the electric car drives down the road, it will be releasing exactly zero emissions.
Carbon Emissions of Gasoline Car
The ICE car releases pollutants and CO2 from its tailpipe, but just how much is spewed forth into the world? According to the Bureau of Transportation Statistics, for every gallon of gas that the ICE car burns, it travels on average 24.2 miles 1, otherwise, known as 24.2 miles per gallon. As the gasoline is combusted in the air, about 73% of the exhaust gas is Nitrogen, and that’s just inert. 13% is water vapor and about 13% is CO2 2. According to the US EPA, one gallon (or 3.8 liters) of gas releases 8.89 kg of CO2 3.
Taking 8.89 kg of CO2 per gallon and dividing by 24.2 miles per gallon, we get a value of 0.37 kg of CO2 released per mile driven or 22.8 kg of CO2 per 100 km.
Fuel Supply Carbon Emissions
Electricity Supply Carbon Emissions – Electric Car
An electric car needs a stream of electrons to recharge its battery every night or whenever you’re going to charge it. Unless this electricity is coming from a renewable or nuclear source, there’s going to be CO2 released during the production of the electricity.
In 2009, over 44% of our electricity in the US came from coal 4. If you’ve ever played a game from SimCity, you know that the coal plants are the first electricity source you build because they’re the cheapest. But you want to replace those things as quickly as you can because they’re so dirty. So how bad is coal? The US Energy Information Administration, or the EIA, puts typical CO2 emissions from a US coal plant at 1 kg of CO2 per kWh of produced electricity 5.
How Much Electricity Does An Electric Car Use?
Looking at our 2020 Model Y, the EPA projects it will consume about 0.28 kWh of electricity per mile 6, but this is only the energy consumed during driving. It doesn’t account for any efficiency losses in all of the equipment getting the electricity from the power plant to the car or from the charging station to the car battery.
After the electricity leaves the power plant, it can travel hundreds of miles across many different wires until it finally arrives at the charging station. As the electricity moves through these wires, any resistance in the wires will cause them to heat up, which represents an energy loss on the part of the electricity flow. The EIA suggests that, on average, about 5% of the energy produced in the power plant will be lost to heat during distribution 7. But just because an electron makes it to the charger doesn’t mean it’s going to get a ride on the big battery.
EV charging stations are notoriously inefficient. Some of the losses are in the components within the charging station. Others are within the vehicle. One group of researchers found that on a typical Level 2 charger, at a current of 40 amps, there was around a 12.4% loss due to charging 8. If we take the Model Y’s consumption of 0.28 kWh per mile and divide by 1 minus the 12.4% of the charging losses and the 5% of the transmission losses, we find that for every mile driven, the power plant must be producing 0.34 kWh of electricity.
Electricity Supply Carbon Footprint
If we assume that 100% of electricity is produced from coal, since 1 kg of CO2 is released by the coal-fired power plant for every kWh produced 5, 0.34 kg of CO2 is going to be released per mile driven, or 21.1 kg per 100 km.
Gasoline Supply Carbon Emissions – Gasoline Car
We’ve expanded the definition of the electric vehicle to include the fuel supply chain, but we haven’t done this for the gas car. Gasoline doesn’t just magically appear at the gas pumps.
Many years ago, in a land, a dino sacrificed its life in the service of your car. Really, in all seriousness, we don’t have to go that far, but there’s significant energy involved in converting the dead dinosaur nectar into gasoline. You have the exploration, the drilling, the transportation of the crude to the refinery, the refining into gasoline and then the shipping of the gasoline to the gas station. Figuring out all of these emissions is really super complicated, and they depend on how the oil is being extracted, how far it has to be transported, in what way it’s transported, and how clean the refineries are.
In a report from the Eindhoven University of Technology 9, they estimate that global drilling for oil releases on average 1.24 kg of CO2 per gallon of gasoline. If you refine within Europe, another 1.23 kg of CO2 is added per gallon. With a final 0.12 kg added for transportation to the gas stations. In total, we’re looking at an additional emission of 2.59 kg of CO2 per gallon of gasoline before the fuel has even reached the car. Dividing 2.59 kg per gallon by our average fuel economy of 24.2 miles per gallon, we get additional emissions for the ICE vehicle of 0.11 kg per mile, or 6.6 kg per 100 kilometers.
Carbon Footprint of Electric Car Vs Gasoline
We get 0.34 kg of CO2 per mile driven released by Tesla Model Y, while 0.48 kg of CO2 per mile (0.37 + 0.11 = 0.48) by gasoline car.
So running our Model Y EV on coal appears to actually be cleaner than running the typical gas-powered car, 0.34 kg per mile versus 0.48 kg of CO2 per mile.
But what if instead of the typical car, we choose something greener, something like say a 2020 Prius Eco. The 2020 Prius Eco gets an incredible EPA combined mileage of 56 miles per gallon 6! With 8.89 kg of engine emissions per gallon of gasoline 3 and 2.59 kg of fuel emissions per gallon, the Prius produces 11.5 kg of CO2 per gallon of gasoline. Dividing by the mileage of 56 miles per gallon, we get per mile emissions of only 0.2 kg of CO2 per mile, or about 40% less than the per mile emissions of the Model Y on coal.
Environmental Impact of Making the Car
There’s one source of emissions that we haven’t looked at. There are emissions that are wrapped up just in making the car, like the emissions from making fuel. Manufacturing emissions are really complicated! For instance, let’s think about what goes into making a tiny bolt.
First, you need to find some iron ore in the ground which means a lot of prospecting and research. Then you need to get some heavy equipment to dig it out of the ground. After that, the ore needs transporting to the steel mill and this could be the whole way across the world. The steel mill separates the iron from the ore in a huge furnace and this is likely coal fired. Then the iron is converted to steel before sending the steel to the foundry for forming into the bolt. Next are all of the forging and machining steps required to cut the bolt and its threads. Once the bolt is made, it needs to be shipped to the manufacturing facility where the cars are assembled. It’s attached to the car and finally, the car is shipped to your local dealership.
This is just for a simple bolt, and I’m leaving out all kinds of steps. But my point here is to show how complicated and how much energy is involved in just making a bolt. Now, imagine all of the complex, specialized brackets, engine components, electronics, glass windows, lights, tires, and all the other components that are really essential in modern cars. To try to get a handle on this, I looked at over half a dozen reports and websites on vehicle manufacturing emissions, and I found that most estimates put light vehicle manufacturing emissions somewhere between 5,000 and 9,000 kg of CO2 10, 11, 12, 13, 14, 15,16. The value for a particular vehicle is really going to depend on the size of the vehicle as well as its complexity and the particular materials it uses. To make it simpler for our purposes here, I’m going to use a value of 7,500 kg of CO2. It really doesn’t matter too much what number we choose as the emissions will be the same for both ICE vehicles and EVs.
In the case of an ICE vehicle, this number does include all of the components of the car, but in the case of an EV, it does not include the emissions produced during the battery manufacturing. Unfortunately, this is not insignificant.
Environmental Impact of Electric Car Battery Manufacturing
According to some researches 13, 14, 15, 16, for an EV with a small battery, like the Nissan Leaf with a 40 kWh battery, the battery production emissions are only about half those of the rest of the car, or about 3,800 kg, but for our Long Range Tesla Model Y with a 75 kWh pack, we’re looking at about 7,600 kg of CO2 released during the production of the battery. This is pretty much the exact same number as the emissions for the rest of the car. So this means that before any miles have been driven, our Tesla has already produced more than twice as much CO2 as a typical ICE vehicle.
CO2 Emissions of Electric Car Vs Gasoline Car Overall
Electric Car Vs Gas Cars: Graph 1 – 100% Coal-Powered EVs
In the vertical direction, we have CO2 emissions in tons of CO2. Just to clarify for those of us on freedom units, one ton here is 1,000 kilograms. Anyhow, along the x-axis is the number of miles driven. At zero driven miles, each of the cars has released CO2 equivalent to its manufacturing emissions, about 7.5 tons for the ICE and hybrid cars, 11.3 tons for the Leaf and 15.1 tons for the Model Y.
As we start driving each vehicle, the Leaf and Model Y increase at about the same rate, with the average ICE car increasing more quickly. We also see that the Prius increases the least per mile. At around 33,000 miles, the ICE car surpasses the lifetime emissions of the Leaf and. The ICE car surpasses the Model Y at around 56,000 miles. Meaning, as long as the coal-powered EVs are driven for more than 56,000 miles, they will both have less lifetime CO2 emissions than the average ICE car. Meanwhile, the Prius keeps looking better and better. By 100,000 miles, we see that its total CO2 emissions are 57% of those of the Model Y!
So why would Elon call EVs sustainable transport? Well, it’s all about this little phrase on my plot, 100% coal-powered EVs. Virtually no electric grid is going to be 100% coal-powered.
Electric Car Vs Gas Cars: Graph 2 – 2019 Average US Grid Electric
Even in the most coal-heavy US state, West Virginia, only about 91% of the electricity is generated from coal 17,18. In some states like California, they only get 0.12% of their electricity from coal 18. In Pennsylvania, it comes in quite low at 16.6% 18. Nationally, around 23.5% of our electricity comes from coal, 39.2% from natural gas and 37.3% is produced by renewable or nuclear sources 18. For the same electricity production, natural gas releases 41% of the CO2 that’s released by coal 5. Nuclear and renewable sources can be classified as emissions-free if you’re not considering the emissions related to their construction, which we haven’t been. What this amounts to is that there are huge reductions in the per-mile EV emissions when we adjust our graph for the current US electricity grid mix.
We can see that by 11,000 miles, the Leaf has a better lifetime CO2 emissions than the average ICE car. It takes the Model Y twice as long to hit the same point, and that’s at about 22,000 miles. However, more interestingly, by 60,000 miles, the Leaf has beaten the Prius. By 100,000 miles, the Model Y is about to do the same thing.
Remember that the Prius represents just about the cleanest gasoline-powered car out there today. It’s significantly more efficient than the typical ICE car. More promising, over the next 30 years or so, the EIA projects the grid will become cleaner and cleaner in the US 19. The coal generation is projected to fall from 21% in 2020 to below 13% in 2050. The natural gas percentage also falls, but just slightly. The biggest change is in the increase of nuclear and renewable sources that are rising from about 40% today to above 50% in 2050.
Electric Car Vs Gas Cars: Graph 3 – Accounting for Changing US Grid
I’m sure you can guess these trends aren’t as dramatic as I’d like to see, but they’re at least in the positive direction. This leads us to a particularly interesting point about EVs. As the grid cleans well into the future, an EV manufactured today becomes cleaner and cleaner relative to an ICE vehicle manufactured today. To account for this, I adjusted the lifetime emissions curves for the year the energy is used in. It’s difficult to see, but the EV curves have begun to bend downward as future emissions become cleaner, according to the EIA trends.
It’s a little more obvious if we extend this out to 2050, which takes us close to 400,000 miles. What we do see is that the points where the EV and the ICE curves intersect, which is the point where the EVs become cleaner than the ICE cars, which means that the EVs are becoming cleaner than the ICE cars at an earlier point in their lifetime. Remember, this is only for cars produced today. ICE cars produced in the future will be more efficient than today, and this will make their per-mile emissions lower. And future EVs will likely be more efficient as well with reduced battery manufacturing emissions.
Electric Car Vs Gas Cars: Graph 4 – 100% Renewable /Nuclear Grid in 2050
So I don’t expect the overall trends between the two vehicle types to change that much, but what would happen if the grid got cleaner than the EIA projects? Let’s say 100% renewable and nuclear by 2050. For this, I assumed an annual compounding increase in renewable generation of 3%, with natural gas and coal decreasing in proportion to their current ratio.
Unfortunately, for a car produced today, we don’t see a significant change in emissions until 2039, after which the emissions curve really begins to flatten. But there is another option that’s available today. And it involves powering your EV using solar panels on your house.
Electric Car Vs Gas Cars: Graph 5 – 100% Rooftop Solar for EVs
And if you were to charge your car using this 100% renewable energy, the CO2 emissions curves become horizontal lines on day one. They’re not perfectly horizontal because there are still going to be emissions that are wrapped up in the production maintenance and disposal of the solar panels.
Granted, I haven’t accounted for any of this in any of the electric sources up till now, but it’s small, and it makes our findings more conservative, so let’s go with it. The National Renewable Energy Laboratory puts this at about 0.04 kg of CO2 per kWh produced 20. As you can see, this is by far the best possible scenario for reducing transportation emissions today.
Electric Car Vs Gas Car Carbon Emissions Tools
Earlier this year, MIT released what they call Carbon Counter, which directly compares lifetime emissions and costs for a wide variety of ICE, hybrid, and electric vehicles 15. I’d highly recommend it. Also, if you’re in the US and you’d like to compare emissions among vehicle types in your particular state. The Department of Energy has a simple interactive tool that is helpful for that 18. It takes into account different electricity generation sources to compare EVs, plug-in hybrids, hybrids, and ICE-powered cars.
Are electric cars better for the environment? The answer is YES, absolutely!
- By comparing the engine and fuel emissions between electric cars (2020 Tesla Model Y) and gas cars, we get 34 kg per mile versus 0.48 kg of CO2 per mile. The electric car outperforms the gas car.
- When we account for the environmental impact of electric car battery manufacturing, electric cars are becoming cleaner than ICE cars at an earlier point in their lifetime.
- As the grid cleans well into the future, and the electric cars will be more efficient with reduced battery manufacturing emissions, electric cars will become cleaner and cleaner relative to gas cars.
- Lifetime emissions of EVs are lower than gasoline cars.