Einstein: e=mc^2; EPA: e=2.5mc^2

I have been trying to reconcile the latest claims by GM and now Nissan that they have electric cars that get the equivalent of 230 mpg and more.  My previous post on energy facts was based on my understanding of the science of physics, but I was worried that maybe I was missing something. My calculations showed that a typical Prius-sized electric vehicle should get around 100mpg equivalent, assuming a conversion efficiency of 100%.  Typical conversion efficiencies of fossil fuels are closer to 40% or 50% in the best case so the real equivalency is more like 50 mpg.  So where did I go wrong?

A couple days ago I read a magazine, Design News, that had been sitting on my desk for a few weeks. There was an interesting article about the 230 mpg Volt. One line in the article confused me: the EPA uses an energy density for gasoline of 82 kwhr/gallon. Strange. I used 34.5. Maybe I was wrong….  I looked at many sources including the DOE and NIST and sure enough, the energy density of gasoline is around 34 kwhr/gallon depending on the exact formulation (in California it is lower, for example).

Next I looked up the EPA conversion factor of 82 (about 2.5 times the actual energy density) to see where they came up with that. I found it in the Electronic Code of Federal Regulation, Title 10, Section 474.3: “If the electric vehicle does not have any petroleum-powered accessories installed, the value of the petroleum equivalency factor is 82,049 Watt-hours per gallon.” So the EPA has decided that the laws of physics are not good enough for them, they need to favor electric vehicle hype by a factor of 2.5. What a fraud.

I then read the “Purpose and Scope” of this distorted computation: “The petroleum-equivalent fuel economy value is intended to be used by the Environmental Protection Agency in calculating corporate average fuel economy values pursuant to regulations at 40 CFR Part 600—Fuel Economy of Motor Vehicles.” Translation: if you sell one electric car then you can sell 20 20mpg cars and claim an average of 30 mpg for your fleet. No wonder GM wants to sell electric cars.

But why would the EPA want electric cars?  They pollute more than hybrid cars because they essentially burn coal, which is known to be the dirtiest source of electric power. I will check and see if I can find the answer to this question on the Internet.


I found the original DOE memo detailing how the electric vehicle equivalency was computed, Petroleum-Equivalent Fuel Economy Calculation dated June 12, 2000. The analysis, by the DOE, starts off in a very reasonable way. The relative efficiency of burning fuel in an engine versus burning it in a power plant is computed yielding a net efficiency for electric power production of 35%, which is exactly what I used in my analysis in an earlier blog Energy Facts. So far so good. Next they multiply this number by 6.67. What? They call it they “Fuel Content” (the quotes are theirs). Here is the reason from the document:

The fuel content factor has a value of 1/0.15 and is included in
the PEF for the reasons described in the notice of proposed rulemaking
and the responses to comments section of this notice. Briefly, these
reasons are:
    (i) Consistency with existing regulatory and statutory procedures;
    (ii) Provision of similar treatment to manufacturers of all types
of alternative fuel vehicles; and
    (iii) Simplicity and ease of use.
The fuel content factor value of 1/0.15 is equivalent to a multiple
of 6.67.

Translation: we lie about electric cars to be consistent with the lies we tell about other politically correct vehicles. One interesting note about this lie: in the comment sections some of the electric power companies want to be a bit more honest about the factor of 6.67, but the California Air Resources Board wants be lie even more:

Comment 6: Assigning one fuel content factor (1/0.15) to all
alternative fuel vehicles is inappropriate since ``the fuel efficiency
benefits of electric vehicles far exceed those of other alternative
fuel vehicles.'' DOE should use a fuel content factor that more
accurately represents electric vehicle benefits in comparison to other
alternative fuels. (CARB)

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