This is a very interesting article about the EPA’s MPGe sticker (found on electric cars such as the Nissan Leaf or the Chevy Volt). Turns out that the MPGequivalent (MPGe) of 99MPGe does not compute. Read on to find out why…
The EPA’s Electric Vehicle Mileage Fraud
In a parking lot near Detroit, General Motors is accumulating Chevy Volts. They cannot yet be sold to the public because the Environmental Protection Agency (EPA) has not yet delivered the required mileage sticker for the window. We can, though, get a preview of how the EPA may complete this admittedly tricky task from the mileage numbers they recently assigned to the all-electric Nissan Leaf. The Leaf’s numbers make it clear that this Administration is willing to resort to accounting fraud to promote its automotive agenda.
The traditional metric for automobile efficiency is miles per gallon (MPG) of gasoline used. But what does MPG even mean for a vehicle that doesn’t burn liquid fuel? Most of us would agree that the Leaf certainly does use fuel — after all, something must create the electricity, and in the US that is generally some sort of fossil fuel. So theoretically we should be able to create an MPG equivalent, or MPGe for short, to measure the fossil fuel use of electric vehicles.
For more than a decade, within the EPA and the Department of Energy (DOE), a number of different approaches to this problem have been discussed. With the release of the numbers for the Nissan Leaf, we now know what approach the EPA is taking, and results are depressing for those of us who would like to see transparency and adherence to science in the Administration. This Administration has a huge intellectual investment in electric vehicles and financial investment in the Chevy Volt. Like a shady company trying to pump up their stock by choosing a series of highly questionable accounting conventions, the EPA has chosen an approach that grossly overestimates the MPGe of electric vehicles.
The Nissan Leaf was rated at 99 MPGe. To reach this number, the EPA created a conversion factor between a quantity of electric energy, measured in kilowatt-hours (KwH) and a volume of gasoline, measured in gallons. They did this be dividing the potential energy or heating value of a gallon of gasoline (115,000 BTUs) by the energy in a KwH of electricity (3412 BTUs) to get a conversion factor of 33.7 gallons per KwH. Using this factor, they can convert miles per KwH of electricity in an electric vehicle to an MPGe that is supposedly comparable to more traditional vehicles.
The problem is that, using this methodology, the EPA is comparing apples to oranges. The single biggest energy loss in fossil fuel combustion is the step when we try to capture useful mechanical work (ie spinning a driveshaft in a car or a generator in a power plant) from the heat of the fuel’s combustion. Even the most efficient processes tend to capture only half of the potential energy of the fuel. There can be other losses in the conversion and distribution chain, but this is by far the largest.
The EPA is therefore giving the electric vehicle a huge break. When we measure mpg on a traditional car, the efficiency takes a big hit due to the conversion efficiencies and heat losses in combustion. The same thing happens when we generate electricity, but the electric car in this measurement is not being saddled with these losses, even though we know they still occur in the system.
Lets consider an analogy. We want to measure how efficiently two different workers can install a refrigerator in a customer’s apartment. In both cases the customer lives in a fourth floor walkup. The first installer finds the refrigerator has been left on the street. He has to spend much of his time struggling to haul the appliance up four flights of stairs. After that, relatively speaking, the installation is a breeze. The second installer finds his refrigerator has thoughtfully been delivered right to the customer’s door on the fourth floor. He quickly brings the unit inside and completes the installation.
So who is a better installer? If one only looks at the installer’s time, the second person looks orders of magnitude better. But we know that he is only faster because he offloaded much of the work on the delivery guys. If we were to look at the total time of the delivery person plus the installer, we’d probably find they were much closer in their productivity. The same is true of the mileage standards — by the EPA’s metric, the electric vehicle looks much better than the traditional vehicle, but that is only because someone else at the power plant had to do the really hard bit of work that the traditional auto must do itself. Having electricity rather than gasoline in the tank is the equivalent of starting with the refrigerator at the top rather than the bottom of the stairs.
An apples to apples comparison, then, would compare the traditional car’s MPG with the Leaf’s miles per gallon of gasoline (or gasoline equivalent) that would have to be burned to generate the electricity it uses. Incredibly, the DOE actually established and published such a standard in a rules-making process way back in Clinton Administration. The standard, called “well to wheels,” adds a couple new factors to the MPGe calculation we discussed above.
First, the DOE looked at the electrical generation efficiency, and determined that only 32.8% of the potential energy in the fossil fuel becomes electric energy in the average US power plant, which it further reduced to 30.3% to account for transmission losses. However, they realized it was unfair to charge electric vehicles for these losses without also charging gasoline-powered vehicles for the energy cost of refining and gasoline distribution. They calculated these as adding 20% to the energy it takes to run a gas-powered car, but rather than reducing existing MPG standards by this amount, they instead gave a credit back to electric vehicles. The 30.3% electric production and distribution factor was increased to a final adjustment factor of 36.5%. This means that the conversion factor discussed above of 33.7 gallons/KwH must be multiplied by 36.5% to get a true apples to apples MPGe figure.
The end result is startling. Using the DOE’s apples to apples methodology, the MPGe of the Nissan Leaf is not 99 but 36! Now, 36 is a good mileage number, but it is pretty pedestrian compared to the overblown expectations for electric vehicles, and is actually lower than the EPA calculated mileage of a number of hybrids and even a few traditional gasoline-powered vehicles like the Honda CR-Z.
Supporters of the inflated EPA standards have argued that they are appropriate because they measure cars on their efficiency of using energy in whatever form is put in their tank (or batteries). But this is disingenuous. The whole point of US fuel economy standards is not power train efficiency per se, but to support an energy policy aimed at reducing fossil fuel use. To this end, the more sophisticated DOE standard is a much better reflection of how well the Nissan Leaf affects US fossil fuel use. The only reason not to use this standard is because the EPA, and the Administration in general, has too many chips on the table behind electric vehicles, and simply can’t afford an honest accounting. In the private sector, this is called accounting fraud and a number of high profile executives are in jail for doing something similar.
Postscript: There is another interesting issue with the Nissan Leaf EPA sticker. The greenhouse gas rating, in the bottom right corner, shows that the car produces ZERO greenhouse gasses (with a note that it applies to tailpipe emissions only). While I suppose this is technically true, it is wildly misleading.
In almost every case, the production of the electricity to charge the car will create incremental greenhouse gasses. One might argue the answer is zero in the Pacific Northwest where most power is hydro-electric, but even in heavy hydro/nuclear areas, the incremental marginal demand is typically picked up by natural gas turbines. And in the Midwest, the Leaf will basically be coal powered, and studies have shown it to create potentially more CO2 in these areas than a car burning gasoline. I understand that this metric is difficult to calculate, because it depends on where and even what time of day the car is charged, but the EPA in all this complexity chose to use the one number – zero – that is least likely to be the correct answer.
Update: Fisker Karma Electric Car Gets Worse Mileage Than an SUV
The Fisker Karma electric car, developed mainly with your tax money so that a bunch of rich VC’s wouldn’t have to risk any real money, has rolled out with an nominal EPA MPGe of 52.
Not bad? Unfortunately, it’s a sham. This figure is calculated using the grossly flawed EPA process that substantially underestimates the amount of fossil fuels required to power the electric car, as I showed in great depth in an earlier Forbes.com article (see above). In short, the EPA methodology leaves out, among other things, the conversion efficiency in generating the electricity from fossil fuels in the first place.
In the Clinton administration, the Department of Energy (DOE) created a far superior well to wheels MPGe metric the honestly compares the typical fossil fuel use of an electric vs. gasoline car.
As I calculated in my earlier Forbes article, one needs to multiply the EPA MPGe by .365 to get a number that truly compares fossil fuel use of an electric car with a traditional gasoline engine car on an apples to apples basis. In the case of the Fisker Karma, we get a true MPGe of 19. This makes it worse than even the city rating of a Ford Explorer SUV.
Congrats to the Fisker Karma, which now joins corn ethanol in the ranks of heavily subsidized supposedly green technologies that are actually worse for the environment than current solutions.
Postscript: I will say, though, that the Fisker Karma does serve a social purpose — Hollywood celebrities and the ultra rich, who want to display their green credentials, no longer have to be stuck with a little econobox. They can now enjoy a little leg room and luxury.