Do Electric Cars have a positive impact on climate change?

In an earlier post, October 11th, I mentioned that I was currently getting 73.5 miles per gallon (3.2 liters/100 KM) on my Prius Plug-In and I received a few comments on this statement. Some people asked how sure I was about the milage and others asked if electric vehicles really made a difference in terms of CO2 and climate change!

The Environmental Protection Agency in the United States rates the car at 95 milers per gallon. Joe Wiesenfelder at cars.com calls the EPA ratings “preposterous” and suggests that the best calculation is to take the gasoline milage and then add the EV range to it. For the Plug-in this would give 50+15 or 65 miles per gallon (3.6 liters/100 KM) which is close to what I get.

In terms of CO2, things get complicated as there are a number of factors which need to be looked at and this can be followed at great length in an article posted by David Nolan on the Tesla S.

Do the Math!

Most analysis start with the carbon emissions from the electricity plants which supply the grid. If the power comes from nuclear, hydro or wind energy, then logically the carbon is close to zero. France, for example, gets 76 % of its power from Nuclear plants and thus electric cars in France will have a much lower carbon footprint than the same cars in the Australia or China where coal represents 69% and 66% of the electricity mix respectively. A different energy mix will give a different level of CO2 production per unit of energy. This is the easy part.

Next, you have to estimate the average electricity usage per mile or kilometer for a specific car and that, of course, depends on how fast you go, driving conditions and if you use air conditioning!

After that comes losses in the system which include transmitting power across the grid, charging and the so called “vampire loss” which occurs at stop lights. All of this needs to be added to the carbon produced in making the batteries and motors and that needs to be divided by an estimate for the distance the car will be driven it its lifetime!

In the end, the answer depends on the reports one chooses to use and the assumptions you make and, of course, different sides to the issue make different points. Most reports give Electric cars a significant advantage everywhere but in the heavy coal countries.

Rare Earth Metals?

One nagging question about many electric vehicles and hybrids is that they are made with large amounts of so called rare earth metals mainly produced in China in reportedly appaling environmental conditions. Can we call a technology really sustainable if it uses hard to get materials which are both strategically and ecologically questionable?