The Clouded Carbon Promise of Electric Cars

The Clouded Carbon Promise of Electric Cars

Michael A. Mazzocco

mamazzocco.blogspot.com

Copyright February, 2018

For some time (a decade, perhaps), I have questioned the environmental costs and benefits of electric cars.  It started with three fundamental, casual observations, none of which I had yet analyzed objectively:

1. The perception that the benefit to owners of electric cars is their ability to say “we don’t pollute HERE (We pollute elsewhere and ship the energy in.  shhh! Don’t tell anyone.).”
2. The environmental hazard of a spent electric car battery is enormous.  A serious quantity and concentration of toxic materials. And they need to be replaced periodically throughout the life of the vehicle.
3. The contribution of carbon dioxide to the atmosphere just might be greater for electric cars than it is for gasoline-ethanol blend (E10) cars because of the loss of energy in electricity transmission and distribution. 

I recently received a report from my power company telling me that their sources of power (53% coal- and oil-fired, 21% natural gas-fired, 16% nuclear, 9% wind and hydro) resulted in the emissions of 1,381 lbs. of carbon dioxide per 1,000 kWhs (kilo Watt hours).  I looked at my bill and discovered that I am emitting about 1,400 lbs. of CO₂ per month in the winter months.  This caused some introspection, to say the least, especially when I multiply that number times the number of households in the country, the continent, or the energy-consuming world.[1]

It motivated me to resurrect the electric-versus-E10 emissions question.  I came up with the following analysis.

Beginning with item 3. above, the U.S. Department of Energy’s Lawrence Livermore National Laboratory reports that in 2016 (the latest graphic available in my limited search) there were 37.5 kWhs of electricity generated nationally for every 12.6 kWhs delivered to residential, commercial, and industrial users.  That is a ratio of 2.98 kWhs generated per 1.0 kWhs delivered.[2]  Most of the rest is lost in transmission. These numbers appear to be relatively constant over recent years.  So about 2 units of electric energy are wasted for every unit that is delivered, on average in the U.S., mostly a result of the delivery system.   Note that the sources of electric power closely resemble those reported to me by my power company.

 Next, I wanted the answer to “what is the electricity consumption of a Tesla automobile in kWhs per mile and per year.  Tesla is widely recognized as an innovative designer and manufacturer of electric cars.  The answer from Wikipedia, which was probably submitted by someone in the industry, is as follows: “The EPA rated the 2017 90D Model S's energy consumption at 200.9 watt-hours per kilometer (32.33 kWh/100 mi or 20.09 kWh/100 km) …  .”  [3]   That is a useful number.  

Next let us assume a person drives 15,000 miles per year, a number I got from a few places.  That means that the following equation estimates the lbs. of CO₂ emitted by the Tesla Model S per year, regardless of where it was emitted:

32.33 kWhs delivered /100 mi. * 1,381 lbs. CO₂/1,000 kWhs generated * 2.98 kWhs Generated/1 kWhs delivered * 15,000 miles/year

= 19,958 lbs. CO₂/year from Tesla Model S.[4]

To compare the same CO₂ output from an E10 vehicle, we need some estimate of miles per gallon (I’ll use 25) and an estimate of CO₂ production per gallon of E10. The U.S. Energy Information Administration tells us that number is 17.6 lbs. CO₂ per gallon of E10.[5]  Thus, the equation forms like this:

17.6 lbs. CO₂/gallon E10 * 1 Gallon E10 / 25 miles * 15,000 miles/year

= 10,560 lbs. CO₂/year from E10.

What is the result?  The so-called “clean energy alternative” car results in the emission of nearly twice as much CO₂ as an average car with an internal combustion engine.  And the electric car dumps its emissions where the power is generated, not where it lives, resulting in a negative externality on the people living near the generation plant. Eventually (quickly) the CO₂ will spread to a more uniform distribution within the atmosphere, resulting in no net gain to the electric car drivers from dumping their initial pollution elsewhere.  And there is the matter of those toxic spent batteries to contend with.

I don’t intend to pick on one car company.  Rather, Tesla and others have made great strides in technology and continue to search for improvements in energy conversion and should be commended for their efforts.  Also, this is not a complete life cycle analysis of carbon in the comparative systems.  One could argue that the CO₂ produced by a diesel tanker delivering the E10 to the gas station should be added to the analysis.  Or how much energy was used in petroleum refining or coal mining and transportation.  And those incremental additions to what should be included could go on and on, which is why people conduct life cycle analyses.  But this review does raise questions about the global impact of eating locally while polluting elsewhere, especially at twice the rate.[6]   It appears the big impact will come from consuming less energy.

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[1] First objective observation on human contribution to greenhouse gasses.

[2] https://flowcharts.llnl.gov/content/assets/docs/2016_United-States_Energy.pdf

[3] https://en.wikipedia.org/wiki/Tesla_Model_S

[4] Take that, you people who say you have no use for algebra!

[5] https://www.eia.gov/tools/faqs/faq.php?id=307&t=11

[6] For fun, multiply the CO₂ output times the number of cars. You will get to the second objective observation on human contribution to greenhouse gasses.