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Crunching The Numbers Behind Pros, Cons Of Electric Cars

FORT WORTH (CBSDFW.COM) – We did a story this morning about electric cars and gas prices. Time and technical problems had me skim over a lot of the information and numbers I used in the story.

The first place to start is probably to explain the numbers and where I got them. Watch the piece –– both parts are embedded above –– and I'll break those down for you.

The U.S. Department of Transportation provided the national averages in commute miles and mileage. Those numbers are 32 miles (the total for both ways) and 17.1 mpg  (this includes trucks, SUVs and cars).

The Texas A&M Transportation Institute studies all things traffic and is a tremendous resource. They provided me with the number of total commuters in the DFW area: 2.9 million people.

Using a national average of 1.2 commuters per vehicle, this works out to 2.3 million cars, trucks and SUVs in the commute.

I applied the number of commuting vehicles to the average commute miles and average mpg numbers. Then I took the average price per gallon of gas from the AAA site for the DFW area. Yesterday that price was $3.57 a gallon.

So here is the big number.

For the commute today in the greater DFW, the cost in gasoline was approximately $15.5 million dollars. Since each gallon of gasoline burned in a car engine creates about six pounds of CO2 gas, about 13,000 tons of CO2 were emitted in the air.

This doesn't include any of the other pollutants, mostly importantly the ones that produce ozone in the lowest level of the atmosphere (ozone is needed high in the atmosphere to protect us from UV radiation; it is bad for our lungs at the surface).

The DFW area is currently out of compliance in regards to our air quality because of ozone.

So $15.5 million dollars spent and 13,000 tons of carbon spewed to get us all to work and back.

What would happen if suddenly everyone drove an electric car instead? Of course this isn't going to happen overnight.

We couldn't make the cars or batteries quick enough to make a change over to electric cars happen any faster than even a decade.  Plus the electric grid would have to grow with the change-over. And of course, this is assuming that people would even want to make the change over.

But what if all the commuters drove electric cars today?

Making electricity also produces carbon pollution, and most of the electricity sold in North Texas is generated from natural gas. An electric provider in California provided this next number I used.

Their website says about .524 pounds are produced at a power plant to make one kWh of electricity using natural gas as the source fuel.

The electric car I drove today, the Chevy Volt, displays how many kWh(s) the car consumed in any one trip.

The car owner is averaging about 34 kWh per 100 miles (he's had the car for almost a year now).  The Texas average cost of a kWH of energy is .12 cents.

At least that is the number I'm using here, you could get a lower rate if you plug in your car overnight when rates are lower (if your electric provider even offers time-tier pricing).

I used these numbers with the same averages I used in the other calculations. This is not supposed to be a definitive study but is for comparison purposes only.

Total cost in electricity: $3.02 million dollars (80% savings).

Total CO2 emissions: 2,600 tons (verse 13,025 tons from gasoline engines, 80% less).

This is just the first story on electric cars.

There is a whole other set of calculations to do on the total cost of an electric car verse an gasoline powered one.

How long would you have to drive an electric car to make up for the price difference? How long before you have to replace the very expensive battery?

Some of the numbers I've seen put the price of gallon at around $7.50 to make the consumer break even over 100,000 miles. We'll be looking at this to see if we can come up with a number of our own.

If you're interested, below is the spreadsheet where I logged all the numbers from the story:

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