Tuesday, October 18, 2011

It takes a lot of “Energy” to make gas... Part Two.

I used coal in the title of the first post as a cheeky reference to the favored argument by EV naysayers that electric cars replace a tailpipe with emissions from a coal powered electricity plant.

They still might want to look in the mirror :)

The previous blog post has been picked up by Autoblog Green and by the Washington Post and dozens of other sites.  This has led to well over 100 comments from individuals debating the statistic  and offering input as to how much electricity and how much energy is required to make a gallon of gas.

Some agree with my conclusions some don’t.   Some say it’s higher some say its lower.   All kinds of data is offered in the comments usually with several zero’s behind it,  cherry picked data depending on the  point of view of the author pro or con.

I wish there were an Energy information Agency FAQ that answered this simple question, How much energy is used to make a gallon of gasoline?

Unfortunately there is not a simple answer and it’s very complicated to find the information to make a compelling case either way. The various nature and different qualities  of crude and the various efficiencies of refineries add to the complexity.

So let’s keep this simple shall we?

Step 1
Let’s begin with the price of a gallon of gas and the percentage of that that goes to refining.   According to the Energy Information Agency on this page http://www.eia.gov/oog/info/gdu/gasdiesel.asp
16% of the August 2011 gallon of gas cost of $3.64 goes to refining cost thus  resulting in $0.58  a gallon in refining cost.

Step 2
According to the EPA and the Petroleum energy guide on this page
(abstract page 3, first paragraph) Refineries spend typically 50% of cash operating costs (i.e.,, excluding capital costs and depreciation) on energy,

So we have 50% energy cost for a refinery, which would result in a cost of energy to make a gallon of gas of $0.29  per gallon.

From here we split off into energy types or feedstocks used to make gasoline.

Step 3
According to the Energy Information Agency,
Just less than  50% of the energy cost come from Natural Gas and about 33% come from electricity,  Also much energy is generated by co-generation, with an undisclosed amount of Natural Gas used to provide electricity for the refinery.

Using the energy cost to refine  of $0.29 and dividing that by 33% gives you $0.10 of electricity cost per gallon of gas.

Step 4 What do refineries pay for electricity and energy?  Good question.  The most they would pay is the wholesale cost of electricity. 

As an energy plant owner myself that has over generated for the year, SDG&E is paying me 3.7 cents per Kwh of generation . You can bet the power plants pay between two and three cents per KWH.

Congratulations, you were a net energy generator!
Account Number: 582687++++
You generated more electricity than you consumed when you trued-up earlier this year. As a result your Net Energy Metering (NEM) account will be credited for the excess generation.

Excess generation:
1607 kilowatt-hours (kwhrs)
Credit per kwhr:
Amount Credited:

With a cost of $0.03 cents a kwh we can come to the conclusion that refineries use around 3 kwh of electricity per gallon of gasoline. 
Furthermore, refineries have nearly 50% of their energy cost in Natural Gas, about $0.14 cents per gallon, If that Natural gas were used in a plant to make electricity an additional 2kwh of electricity per gallon would result for a net total of 5 kwhs of electricity per gallon of gas. 

Using these simple government non biased information websites of the US Energy Information Agency and the EPA, as well as my own payment from SDG&E, the information resulted in a 5kwh of electricity used  to make a gallon of gas. Not to far off of my original estimate of 6kwh per gallon of gas.   Throw in unknown energy cost to extract, pump, ship, store, truck and sell, I am confident an additional kwh or two would be added to that figure.

I stand by original conclusion that a gas car with an average fleet 22mpg will use more electricity (or if you prefer, electricity equivalent in energy units) used just in the refinery process to drive 100 miles as compared to an electric car.

Add to the discussion, what do you say?  


Mini-E # 183, 34,000 sunshine powered miles.


  1. There are really cars that consumes too much energy, cars however are designed specifically, with different power functions, and if I were to ask, I would of course choose electrical cars, it's not just eco-friendly, it's a practical way to save energy too.

  2. Humm.. you missed a KEY step. Call it step 0, it takes 9kwh and 1000 cu ft of natural gas to extract a barrel of synthentic crude from the oil sands of alberta. Then there is the 10 kwh needed by the 30 electrical pumping stations to move that crude 1600 miles to the refinery.
    Assume instead that the same 1000 cu ft of gas is good for 160kwh of electricity if its burned in a new 60% efficent natural gas plant.

    Call it 180 kwh per barrel. Since each 42 gallon barrel of crude only produces 36 gallons of product, (19 gallons is motor grade gasoline but lets use the 36 to be nice) then thats 5 kwh per gallon BEFORE it gets to the refinery. using your 5kwh for the refinery, thats a total of 10 kwh.

    Please update your math and stop ignoring where the real energy is used, in extracting and creating crude oil from heavy oil sources.