99 MPG 'equivalent' EPA rating for Nissan Leaf is a fraud, and here's why

from theblogprof by The blogprof



99 MPG 'equivalent' EPA rating for Nissan Leaf is a fraud, and here's why: "Here's the sticker that is going on the Nissan Leaf courtesy of the government (minus the red circles that I added):

From Auto Blog via Instapundit: Nissan Leaf snags 99 mpg rating on official EPA sticker

As far as we know, the first production Chevrolet Volt models are still awaiting their official EPA stickers. Nissan, though, has received the details on what the government agency has rated its all-electric Leaf at, and it looks good: a combined rating of 99 miles per gallon (equivalent) which breaks down into 106 city/92 highway. The official EPA range for the car is 73 miles, which Nissan admits is a variable (we know it can be beaten), and the annual electric cost is estimated at $561. The Leaf is the first vehicle to get this new label, Nissan spokesperson Katherine Zachary told AutoblogGreen that 99 mpg puts the Leaf way in front into the 'best' fuel efficiency rating for mid-size vehicle class. It'll be interesting to see how Nissan uses this in upcoming advertisements, especially since the company has called the car a compact in the past.

So, how does the EPA calculate mpg for an electric car? Nissan's presser says the EPA uses a formula where 33.7 kWhs are equivalent to one gallon of gasoline energy. Also, the EPA determined the Leaf's efficiency is 3.4 miles per kWh, another number you can easily beat while driving, as the driver info screen can prove. Since the Leaf has a 24 kWh battery pack and can go, officially, 73 miles, then, the EPA says, it could theoretically go 99 miles if it had a 33.7 kWh pack (and everything else about the car remained the same). Make sense?

That part does, but there's more to the story. The 'miles per gallon equivalent' is a fraud perpetrated to hide the true environmental cost of these cars. One gallon of gas does have about 33.5 kW-hrs of chemical potential (depending on blend, additives, etc). But here's where the fraud is perpetrated - the electricity is being generated by coal power plants that are only about 33% efficient (minus transmission losses and losses from charging). Coal plants are off-site power generators (whereas car engines are on-board) and they are totally ignored in the EPA rating.

Let me illustrate by example how the fraud works. Let's say that you took your gas-guzzling engine out of your car and hooked it up to a generator in your garage. The engine has a fuel efficiency of 15 MPG. That's about 25% efficient. You run the engine to generate electricity to charge your Nissan Leaf. Guess what the mileage of that Leaf is? The EPA says you will still get 99 MPG overall. But you actually used 4 gallons of gas to get that far, not one (remember that the electric generator is 25% efficient) The real efficiency is 25 MPG (equivalent), not 99.

Conveniently, the EPA is hiding the fact that you are simply displacing gasoline usage with coal. The fact that you don't have to directly throw coal into your car doesn't mean you aren't using any. Indeed the overall efficiency of electric vehicles charged on coal is no better than a car with a spark ignition, and far short of the efficiencies achieved with diesel.

Just in case anyone out there is opining that we should therefore go with 'renewable sources' (ie - wind, solar etc), let me just point out that that will make the available energy problem even worse. Read: What is renewable energy? It is pie in the sky, but no free lunch. Nature will always get its pound of flesh.

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