Internal Combustion versus Electric Drive

Mar 11, 2018

A brief review of the 2006 book "Internal Combustion" by Edwin Black and a energy density comparison of a Chevy Bolt V a 32 MPG Gasoline powered car.

Recently I just finished reading a book titled “Internal Combustion” by Edwin Black. This is not a new book as it was published in 2006 but it has some good history in it. However since it predates the newer versions of the Lithium Ion Battery powered EV in the last few chapters the author discusses the prospects for a Hydrogen Economy which I view as still a dead end.

In the book Edwin Black discusses the early permutations of the battery powered electric car in our larger cities and the effort by Thomas Edison and Henry Ford to collaborate on producing a Model T Electric Car with more range. Edison’s goal was to produce a battery with a capacity of one Horsepower Hour per 55 pounds of battery. The battery pack in the Model T they were working weighed 1,200 pounds which meant it would be capable of delivering about 22 Horsepower Hours. It was projected to have a 75 mile range.

Considering that there were few paved roads outside of cities at the time, this is a pretty good range. Edison envisioned a whole home system with batteries to power the house in a power outage, a gas powered generator to recharge the batteries, and the car. We are talking about 1914 and there were a lot of potential customers out in the Midwest who did not have grid power or access to even gas stations.

Then the Edison Battery Factory mysteriously burned down to and World War One started. It is not common knowledge even today that World War 1 was an oil war fought in part over securing access to Middle Eastern Oil. Up until the war America had been Britain’s main oil supplier.

The story moves on to the skullduggery surrounding the management and mismanagement of the only electric train line in the United States in the 1920’s, the Milwaukee Line. A Rockefeller even sat on the board so you can imagine some of the schemes that were hatched to bankrupt a railroad that had lower operating cost than any other railroad. They finally succeeded in driving it completely out of business just prior to the first Arab Oil Embargo in 1973 ironically enough. To this day United States companies manufacture electric train assemblies which are shipped overseas.

Then the story shifted to the Electric Trolley and the decade long combination of GM, Firestone, and Standard Oil to destroy and dismantle the trolley lines in most major cities of the United States. This is not a conspiracy theory; they were actually convicted in court in 1947 for this criminal conspiracy and officially slapped on the wrist. By then it no longer mattered, the Electric Trolley was dead from so called progress.

All of this set me to thinking about using the Horsepower Hour content of Lithium Ion Batteries as compared to Gasoline to showcase the inefficiency of the internal combustion engine. Since one horsepower is defined as 746 watts, and one horsepower hour is defined as 746 watt hours, this should be a relatively strait forward matter.

FYI, there are 32.777 Kilowatt Hours of energy content in a gallon of gasoline which works out to 43.936 HP Hours.

I am not going to publish the table I worked up here because of the formatting issues for tables creates some difficulties however I will summarize the table for you and point out some of the more pertinent comparisons.

In the table I compared a Tesla with a 85 kWh battery pack, a Chevy Bolt with a 60 kWh pack, and a Nissan Leaf with a 40 kWh battery pack.

We will compare the Chevy Bolt to a standard gasoline powered vehicle capable of 32 MPG, like a Honda or a Camry with an 18 gallon gas tank. Spoiler alert here, an 18 gallon gas tank holds up to 590 kWh’s of energy which equated to 25,960 Horse Power Hours of energy. Our Chevy Bolt only contains 60 kWh’s of energy which equals 2,640 HP Hours. In other words the 18 gallon gas tank contains 9.8 times more energy which is the meaning of energy density.

Weight per unit of power is the key definition of energy density here. A Chevy Bolt 60 kWh battery pack weighs 959 pounds, while an 18 gallon gas tank only weighs 113 pounds which equates to ratio of 8.4 /1.

Things aren’t looking good for Lithium Ion battery packs as compared to gasoline prompting some people to wonder just what the attraction of electric drive is.

Here is where things get interesting. A Chevy Bolt has a range of 239 miles while a 32 MPG gas car only has a potential range of 576 miles. What gives, gasoline has 9.8 times the energy content with 8.4 times less weight but the engine is only capable of 2.4 times the range. Something is terribly wrong with Internal Combustion that isn’t readily apparent when looking at the energy content of the fuel by itself.

When you look at the HP Hour content per pound of fuel or battery the same problem shakes out, gasoline is clearly superior. However when you look at the Horse Power Hours required on average to go a mile electric vehicles are clearly superior. Our hypothetical Chevy Bolt only needs 11.4 HP Hours per mile on average while our ICE vehicle requires 45.07 HP Hours per mile. In this instance the motor and drive train of the EV is 3.9 times more efficient.

What we need to ask ourselves is what do we need most in our modern transportation fleet? Is it cars and trucks that pollute the air we breathe, warm the planet due to their CO2 emissions, and need three to four times more energy per mile to move us, or are quiet, non-air polluting, and potentially carbon emission free transport be more important to us.

The internal combustion engine has had its run, and it is clearly at the end of it when you look at the facts and the numbers.

Many people will miss the combustion engine, I will not. Some people are nostalgic for the horse and buggy but they would not be if they could visit in a time machine a major city in the 1890’s powered by horses. Besides, the stink, the flies, the noise, and the dead horses in need of disposal there was another drawback. That was the cost; it cost twice as much to operate a horse and buggy, which is why the automobile took over from the horse. Ironically enough it cost twice as much to operate an internal combustion engine car as it does to operate an electric vehicle. Gas powered cars are already looking quaint.

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