EV-ICE Cost and Carbon Comparison Tool

Compare Your Current Gas Vehicle to an EV

A couple of weeks ago, I got curious about a real, measured method for comparing EVs with their gas-burning internal combustion engine (ICE) counterparts, and I posted this article using averages. Given the variables, however, I realized that the averages don’t always apply, and in a given situation, what looks like a big carbon benefit for EVs might actually be the reverse—it depends on variables like the efficiency of the ICE car you are replacing, the efficiency of the EV, and the sources of your electricity. It seemed necessary to set up a way to compare these based on the data that are specific to your situation.

But then another question entered as well. It’s all fun and good to reduce carbon emissions, but as soon as you demonstrate that it works, people like me wonder—“But does it cost more?” Again, the answer is specific to a situation. The electricity to power EVs is measured in kilowatt-hours (kwh) and the cost per kwh varies widely depending on where you live, whether or not you have your own renewable source of electricity and the local cost of charging stations if you need to use them. It also depends on the price of gasoline, which can also vary widely by region, and from week to week or month to month. So these variables need to be accounted for in a cost calculation.

To take a look at the effect of these variables on a case-by-case basis, I developed a spreadsheet that enables the user to input the relevant data specific to their situation, and then see how the two vehicles compare. You can use it to compare annual usage or even for something as small as a 300-mile trip. You just need to enter a few data points, and the spreadsheet will calculate your comparisons. I’ll show you how to get a copy of the spreadsheet in a moment. First, I want to identify the inputs you will need and clarify the assumptions used in it.

The Inputs You Will Need

Three key inputs are required: The average miles per gallon (MPG) you get in your vehicle, the average kwh/mile for your EV, and the percentage mix of your sources of electricity—coal, oil, natural gas, or non-emitting sources like nuclear and renewables. When you enter these figures, you will get the carbon comparisons based on the assumptions outlined below.

For operating cost comparisons, you will need to estimate your cost per gallon of gasoline for the ICE vehicle. Usually, the best way to do this is to consider the preceding six months in your area and use a price that is close to what you have experienced.

To calculate the cost per kwh for your electricity, however, you should pull together a year’s worth of your electric bills so that you can enter both your monthly total cost and your kwh usage, which will help determine your cost/kwh. Although electric bills often list a $/kwh cost, the additions and variations on the bill add up, so the easiest way to estimate total cost is to divide total kwh usage by the total monthly bill in most cases. Just enter the proper numbers into the spreadsheet, and it will calculate it for you.

Assumptions on Carbon Emitted from an ICE Vehicle

According to many sources cited in the original article, CO2 is produced at 8,800 g (8.8 kg) per gallon of gasoline burned. In addition, CO2 is emitted during the refining of gasoline at a rate of 1,112 g (1.1 kg) of CO2 per gallon, for a total of 9,912 g (9.9 kg) of CO2 per gallon of gas burned. These are the assumptions built into the spreadsheet on ICE vehicles. Using your average miles per gallon, the spreadsheet calculates the carbon per mile driven.

These two sources are the primary contributors to operating emissions for an ICE. Although theoretically, you could include all the other carbon costs associated with gasoline refining, including oil production, transport, exploration, and so on, visibility to real data on these gets increasingly difficult and the contribution to the overall picture gets smaller and smaller. The spreadsheet uses only the two inputs mentioned above to calculate the carbon emissions of ICE vehicles.

Assumptions on Carbon Emitted from EV

EV emissions are dependent on two key factors as well: efficiency and electricity source. ICEs measure efficiency in terms of MPG, whereas EVs measure it in terms of kwh/mile. Currently, EVs have a wide range of efficiency ratings, from a low of about 0.24 kwh/mile to a high of 0.87 kwh/mile. The actual rating of your EV will have a decisive impact on the comparison. So, you need to know the efficiency rating of your EV to figure this out. The EV manufacturer has a number for your vehicle, but like with MPG ratings, it will depend ultimately on how you drive and your local driving conditions.

A separate set of assumptions is made about carbon emissions based on electricity sources. As I stated in the original article:

As a rough guide coal has a carbon intensity of about 1,000g CO2/kWh, oil is 800g CO2/kWh, natural gas is around 500g CO2/kWh, while nuclear, hydro, wind, and solar are all less than 50 g CO2/kWh.

In other words, electricity from natural gas emits ten times as much carbon as nuclear and renewables, and electricity from coal emits a whopping twenty times more carbon than nuclear and renewables. Hence, the higher percentage of your electricity that comes from coal, the higher the total EV emissions produced by driving your vehicle will be. In most cases, your local utility is probably the best source for finding out what percentage of your electricity comes from what source.

How to Get the EV-ICE Cost and Carbon Comparison Spreadsheet

There are two ways to get the spreadsheet. Paid subscribers will see free access instructions below the paywall at the end of this section—but act soon because the free offer is time limited.

Free subscribers can use this link to purchase the spreadsheet at Gumroad for the nominal price of $6. You could also subscribe for $5 a month and get instant access to the spreadsheet.

When you get the spreadsheet, will also receive a free bonus: PDF copies of three recent articles I have published about EVs (including this one) and why switching to EVs is an important contribution to the climate solution.

Let’s solve climate change now! We can do this.