Anablog

I got a little more insight on how electric car companies can claim 135 mpg when they are not using gallons. Like most disreputable things in life, it comes from the government. This silly article in the NY Times called out the phrase “Petroleum Equivalency Factor” and that is a bit suspect in a country where electricity ranges from 7 cents to over 22 cents a kwh and where gasoline has a similar range. It took a few seconds on Google to come up with this page on the petroleum equivalency factor. This is a section of the federal law that just mandates that a gallon of gas is equivalent to 82 kwh. If you have petroleum accessories installed, I think that means a heater, then you only get 73.8 kwh in your mythical gallon of gasoline. What this is trying to do is establish a fixed ratio between the cost of gasoline the cost of electricity. Note that here in California where I pay 22 cents a kwh, this mythical gallon of gasoline would cost 18 dollars. Even at my 13-cent baseline rate that I already consume with the refrigerator and lights, this mythical gallon costs $10.66. Out in West Virginia where people pay 7 cents a kwh, the government mandated mythical gallon would cost 5.74.

This is problematical, to say the least. But look at what this does for those trying to say you get 100 mpg. I think I have made a pretty good case that a Chevy Volt can go 40 miles on 16 kwh and a Geo Metro gets about 36 mpg. 36 and 40 are close enough to equate for a back-of-the-envelope calculation. Now what the government is saying is that you can burn up 82kwh and say that you used a gallon of gasoline, when in reality it is maybe 16 (or some people that commented on my last post insist is 8 kwh). Well if the reality is that you can go 40 miles (a gallon’s worth of gas) on 8 kwh and the government allows you to use 82 kwh, well what this does in put a factor of 10 on this phony “equivalent” fuel economy. Now does the electric car really get 13 mpg? No, that is equally absurd. It all depends on what you pay for electricity and what you pay for gasoline. Today right this minute I am pretty confident $2.25 cents gasoline is a cheaper fuel than 22 cent a kwh electricity. And that is all I am trying to say— the electricity cost is not negligible, not even if you pay 7 cents a kwh. For me at this moment is more expensive to “fuel” an electric car but that is only my situation. As all the comments in last week’s blog pointed out— gasoline is sure to go back up to 3 or even 4 bucks soon, and most people don’t pay 22 cents for a kwh. True. Maybe one day gasoline will be 5 dollars a gallon and PG&E will let me buy off-peak electricity for 7 cents a kwh. If you look at a Volt and a 40 mpg car, that means it costs 5 bucks to go 40 miles in the gas car and $1.12 to go the same in the electric. That is great, but the dollar is still not negligible, it has to be accounted for just like all the other costs.

Now in last week’s blog I did jump around a bit— considering the Volt as both a pure electric and as a hybrid, and was rightly criticized for it. But see, GM themselves say the Volt is a different beast and that it should be thought of as a pure electric car that has a gasoline assist motor that only gets used when the battery pack is dead (50% empty according to the first commenter in last week’s blog, 25% according to cited sources in Wikipedia). So now lets assume that you have exhausted the battery pack in your Volt and are running on gasoline. This is where this 100-mpg rating fiasco is really approaching actionable fraud. See, when you have a series hybrid, the efficiency of the gasoline motor is severely impacted because you have to take the mechanical energy and convert it to electricity, and then convert that electricity right back to mechanical energy with the motor. Note the Wikipedia article calls out that the Volt has a 111 kW electric motor, and a 52 kW generator. This means if the pack is depleted to the point that it cannot even be used as a booster, your car now has about half the power it did when it was on pure electric. You won’t consume 53 kW continually unless you are towing or going up a hill, so hopefully you will charge up the batteries enough so that you have some backup charge for on-ramps and passing. But now think about this mode— your gasoline engine is not only powering the car, it is also charging up the batteries. You will be lucky to get 35 mpg in this mode, and maybe 45 mpg once the battery stops sucking juice and you are really careful driving. The car will just be a series hybrid that gets worse mileage than any Prius. Toyota engineers were not stupid when they made their car a parallel hybrid.

So bottom line, electricity is not free and the government lies. No big news. As before, I would like to see the electric companies pledge to let us draw power for electric cars at 10 cents a kwh or less. As to mpg ratings on the electric portion of a car, lets just go to cost per mile and forget gallons and kwh.