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Fisker Karma: Worse Mileage Than A Ford Explorer

October 20, 2011, 3:55 pm

The Fisker Karma electric car, developed mainly with your tax money, has rolled out with an EPA MPGe of 52.   But this number is bogus.  The true MPGe is worse than a Ford Explorer.  Learn why in my Forbes.com piece.

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Category: Energy, Environment, The Corporate State
  • me

    Argh. Fully expected, deeply depressing.

  • lj

    "has rolled out with an nominal"

    s/an/a/

  • robert

    Mike there are several pieces missing from the equation. First oil is distilled using fractional distillation. From every barrel of oil (42 gallons) only 19 gallons of gasoline is produced. Off the top that is 50%+ loss.

    Now we must compare this with power plant efficiency. The number quoted 35% is for a first generation fossil fuel plant. This number does not apply to nuclear, hydro, or natural gas turbines. A co-or tri gen natural gas turbine runs in the 60% range. Renewables like hydro/wind/solar and nuclear cannot be compared in this way as they are not "using" fossil fuels. We must also look at how power is generated. Demand is at it's peak during the day, and goes down at night. Plants cannot simply "shut down" as consumption decreases. A fossil fuel boiler must continue to burn fuel in anticipation for the daytime demand. At night a plant will vent excess steam into the atmosphere and uncouple a turbine from the system. During the day that turbine will come back online using the excess steam. Electric cars will charge at night - soaking up the excess capacity that would normally be lost. Providing a win for the power companies, and increasing the efficiency of the system.

    Secondly there is an efficiency rating missing for both engines. Lets say we have a gasoline motor in top condition, we can expect an efficiency of 25%. Note this number will decrease as the car ages. An electric motor in top condition will be around 92% efficient. This will remain pretty well constant for the life of the electric motor. Also one must take into account the hydrocarbons that will not be used (engine oil ect) with the EV.

    The number the EPA is using is for simplicity, although it is not far from the truth. EV's at a minimum represent a 3x increase in total system efficiency over a conventional gas power vehicle. Your columns however represent a complete lack of understanding on how electricity is generated, the losses involved with the oil refining process and workings of ICE and electric motors. I find it really hard to believe that you have a ME degree from Princeton.

  • Rob

    Your article is linked on drudgereport.com

  • Arthur Felter

    Warren, I read the article, and for reference jumped over to the referenced article you wrote about how and where the 36.2% comes from. In reading this, I think you're right and I also think you're wrong (unless I'm doing some incorrect math, which is highly plausible).

    In the referenced article there is an image of a Nissan Leaf's fuel economy sticker which says that a Leaf will require 34 kilowatt hours to travel 100 miles. My power company charges me about $0.10 per k/w hour (rounded for ease of use), which means that it costs about $3.40 to drive 100 miles. Gas around my neighborhood is going for about $3.50, which to me means the car has a rough equivalent of 100 mpg (as purported) in terms of dollars spent.

    Sure, I understand that there may be some energy loss when the power was produced, but dollar for dollar the Nissan Leaf goes 100 miles for the same amount of money it takes to buy a gallon of gas.

  • Arthur Felter

    And by 36.2% I mean 36.5%...

  • Punkster

    Congrats, you made Drudge!

  • Punkster

    2Robert, isn't the rest of the 42 gallon oil barrel used for other things - like the heavier components are used for synthetic fibers and such ( oil, including crayons, plastics, heating oil, jet fuel, kerosene, synthetic fibers and tires.­)?

    So you can't just claim that half the energy in a BBL of oil is just wasted, since it is used for other things. You have to apportion the energy based on usage.

    In fact I would guess that a fraction of a percent of a BBL is actually discarded.

  • Andrew

    I thought Fiskars made scissors.
    And my Gerber camp hatchets.
    Cars?
    I'll make some, call my company Andrewlyndra and start shoveling the pork money my way!
    Oink oink!

  • robert

    It is used for other things - but here is the kicker.. If we were not refining to produce gasoline, we would end up with more of the less refined fuels per barrel. That would mean that we could meet our existing demand for those fuels by refining HALF of what we do now. What we are doing now is refining oil to mainly produce gasoline, which then is transported using more fossil fuels to be burned in engines that are only 25% efficient when new. The byproduct of a power plant IS the complete end product. And power plant efficiency and emissions can be controlled while millions if individual ICE engines cannot.

  • Curtis

    Warren is correct from a total power point of view but misses one big point.

    Electricity is basically free at night. Rivers keep generating hydropower. Nuclear and coal plants run regardless of demand creating an excess. Electric cars are storing the free electricity in their batteries to be used the next day. It is an inefficient process but it clearly better than letting the energy go to waste. There have been lots of suggestion about how to use night time electricity and electric cars are the best currently available technology.

    An electric car charged at night is the most efficient car possible. For the reasons Warren mentions, charging one during the day is not.