If all cars in the US suddenly become electric, how much more electricity do we need to produce (in percentage)?

Let’s do the math.

In 2012, the US consumed 133 billion gallons of gasoline. In 2012, the US consumed 133 billion gallons of gasoline.

The average gasoline thermal energy content is 33.41 KWh/gallon.
Gasoline gallon equivalent

This is 4,443 TWh per year of thermal power that goes to gasoline-powered vehicles in the US. It would take 1,111 tonnes of electricity to replace the gasoline energy if electric vehicles are assumed to use 4x as much energy as gasoline vehicles.

In 2011, the US consumed 3882 TWh of electricity.
International Energy Statistics

The increase in annual electricity demand would therefore be 29%.

Let’s now see how this affects CO2 emissions.

8.887 grams of carbon dioxide are contained in each gallon of gasoline
References and Calculations

The CO2 reduction due to avoided gasoline consumption would equal 1182 million tonnes CO2 per annum, assuming that demand doesn’t rise to compensate. This is before increasing electricity use.

Assuming that the additional electricity comes from non-base load sources (as nighttime chargers are likely to), then the CO2 emissions per KWh of electricity are 689 grams.
References and Calculations
Electric Vehicles: Myths and Reality

The total increase in CO2 emissions due to increased electricity consumption would then be 765 millions tonnes of Co2 per annum. The net reduction in CO2 emissions would therefore be 417 millions tonnes.

The US CO2 emissions total in 2012 were 6,526 millions tonnes.
U.S. U.S. Greenhouse Gas Inventory Report

The net reduction in CO2 emissions from the country would therefore be 6.4%

[Update: Graham Katz pointed to the fact that I have neglected CO2 emissions from refinery, which is a valid point. The US refinery emissions from gasoline are 130million tonnes. This increases the CO2 reduction by 6.4% to 8.4%. There are many factors that can be added to the analysis that will either increase or decrease emissions. I won’t go into detail about them because they could cause an increase in cost. An exhaustive accounting would consume hundreds of pages.]

Let’s now look at the cost.

The average US car cost is $25,000.
Passenger cars in the United States

Pre-subsidy, electric cars cost around $40,000. This will drop with increasing scale. The “average” car price of $25k today includes heavy vehicles and diesel-burners, which can skew the average price. Smaller gasoline vehicles, which are great candidates for EV replacement, are often less expensive — maybe $20k on average. EVs are $20k cheaper than comparable gasoline vehicles, based on current costs. Let’s say it is $30k for an electric car of economy-of-scale. For a good number, this is $10k less than gasoline.

There are two cost scenarios to be aware of. It is better to switch all cars immediately than just replacing them with electric cars.

  • To make the switch “instantaneously”, approximately 150,000,000 vehicles must be replaced right away, and gasoline cars will lose all their value. This would cost $4.5 trillion.
  • The “gradual” switch is where gasoline cars are used until their end of useful life. This cost increase can be compared to a business-as usual case. The cost would then be $1.5 trillion.

These numbers seem conservative to me. The reality would likely be somewhere in between.

If we take the $1.5 trillion number, it gives us an annual effective CO2 reduction cost of $3600 per ton CO2. If amortized over a 30-year vehicle life, which I believe is very optimistic in the US, that yields $120/tonne CO2 avoided. This is quite costly.

While EVs do offer long-term fuel savings, the rest of the math seems very conservative. I don’t feel guilty about not mentioning this. Reduce the vehicle’s expected life to a more realistic figure (taking into account battery longevity) or retire more gasoline vehicles aggressively and the net $/tonne CO2 amount will be about the same.

I will stick with $120/tonne — it seems reasonable to me. If you have a better estimate, feel free to comment in the comments.

According to current industry estimates, the cost of carbon capture and sequestration in coal power plants is $80 per tonne CO2. For enhanced oil recovery, the CO2 has an estimated economic value of $40/tonne. CCS’s net economic cost is therefore $40/tonne. These numbers don’t scale linearly but the marginal electricity costs and CCS costs do not. It is possible that it washes out.
Journal of Petroleum Technology February 2014 Page 47

Given the current US power mix, electric vehicles can be a very poor way to reduce CO2 emissions. Fitting coal plants with carbon capture systems can do three-times as much good for a dollar. There are even better options, such as replacing coal plants with nuclear, wind or combined-cycle gas plant. Massive increases in renewables generation are required to make mass rollout of electric cars worthwhile. Maybe we will get there in the future. However, today’s market trends don’t support this assumption for the next few decades.


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