Critics are often quick to point out that car companies are somewhat disingenuous when they use the phrase “zero emissions vehicle” when promoting their all-electric offerings. The term “elsewhere emissions vehicle” has been suggested as a more accurate description, on the basis that many electric vehicles (EVs) get their juice from coal-fired power stations. To get around this, sometimes EVs are marketed as having zero tailpipe emissions.Either way, to compare the emissions of an EV with those of a gasoline powered vehicle, it is appropriate to factor in an EV’s carbon footprint based on its power generation source. Then we can compare their emissions with those of gasoline powered vehicles over a given distance traveled.
Here’s an interesting thought experiment however, one which kind of turns the discussion around. What if we consider all vehicles to be electric vehicles, even the ones we fill up with petroleum products? We certainly should if we are trying to be accurate in our comparison.
First of all, why would we want to look at it this way? Well, the fact is, without the generation of huge amounts of electricity, we don’t have gasoline in the first place. Forget about getting crude oil out of the ground thousands of miles away, transporting it by super tanker, storing it, and getting it to the gas station – all of which impacts the carbon footprint too – lets just consider the process of refining it, which itself, directly uses electricity. Bottom line – No electricity, no gasoline. The question is, how much electricity?
The Gateway Electric Vehicle Club ponders this on its website. They asked how much electricity is used to produce a gallon of gas, and to answer it, they approached an obliging Department of Energy for help. The DOE did not answer the question directly, but instead tackled the problem by identifying the energy loss during the refining process. It turns out that refineries operate at an 85% efficiency rate. The consequent 15% efficiency deficit translates into a 6 kilowatt hour(Kwh)per gallon energy loss from refining. To put it another way, there is a opportunity cost here. 6 KwH of electricity that could have been available directly for a plug-in vehicle is lost in order to produce one gallon of gasoline from crude oil. And to put that into perspective, 6 KwH is good for about 20 miles of motoring in an electric car.
It is, of course, very difficult to make entirely accurate comparisons between EVs and gasoline powered cars, as there are so many variables. But while it may be disingenuous to call electric cars zero emissions vehicles (though, of course, they can be) it is worth remembering that fossil fuel based vehicles exert their own carbon footprint based on their use of electricity, too