Now if you're in a country where close to 100% of power is produced from non fossil fuels, eg solar, wind, nuclear etc, then its definitely a win for the electric car. However if you have a mixture of coal and non fossil fuels, it seems to be it boils down to energy efficiency of your electric vehicle vs the standard car. To elaborate, even if I say I my electric car is powered by electricity generated by wind farms, if I divert x number of joules to my car, I am also preventing this same number of joules from powering someone else's home or business. Therefore they will just turn to coal to power it, and we burn coal to produce the x number of joules which would otherwise be generated from non fossil fuels.
Bearing that in mind, lets consider the following vehicles. For the fossil fuel car, I am going to choose the Nissa Tiida, since thats the car I am currently driving. For the electric car, I will consider the BYD e6, ( https://en.wikipedia.org/wiki/BYD_e6) which would be the car I would most probably drive if electric car infrastructure was a thing in my country and if electric vehicles were easily available. This car has been used for police and taxis in various countries so I figured it would be reliable.
According to wiki, the BYD e6 can go 300 km with 75kwH, ie 25kwH per 100 km. According to this website 1 kg of coal generates 8kwH of heat (hey, it uses figures in kwH instead of joules, saving me the hassle of converting
![Very Happy :D](./images/smilies/icon_biggrin.gif)
http://www.greenfacts.org/glossary/pqrs ... nology.htm
This means to achieve 100 km in this car, we must burn 25 /8 x1 x 100/45 (efficiency calculation) of coal, ie 6.94 kg of coal.
The conversion of coal or petrol into CO2 is given in this website https://people.exeter.ac.uk/TWDavies/en ... 0fuels.htm but petrol gives 2.31 kg of CO2 per litres, and coal gives 2419 kg of CO2 per tonne of coal burnt (I know this varies depending on the type of coal, so this is only a rough calc).
So 6.94 kg of coal gives 16.8 kg of CO2 per 100 km of travel.
Now lets consider the petrol car. As mentioned I drive a Nissan Tiida, so lets use their numbers for comparison.
http://www.auto-data.net/en/?f=showCar&car_id=694
The fuel efficiency varies between model for the car, but an "urban" model gives 8.9 L / 100 km and an extra urban gives 5.7 L / 100 km. For now I will use the first set of numbers. Again using the carbon emission converter from above, 1 L of petrol gives 2.31 kg of CO2, so 20.559 kg of CO2 / 100 km. So its around 20% more carbon emissions than the electric car. However if we take the more fuel efficient version of the Tiida, at 5.7L/100 km, we know get 5.7/8.9 * 20.559 and we get 13.167 kg of CO2 / 100 km, which is better than the electric car.
So it seems that unless you a) have solar panels and can produce sufficient energy to power your own car or b) the infrastructure of power generation utilises mainly non fossil fuels, it seems the better way to minimise your carbon emissions from driving, is a more fuel efficient petrol car rather than an electric one.
In case anyone is wondering, I can also run the figures for the Tesla model S, the most widely sold electric car, which has 38 kwh / 100 miles or 38 kwH / 160 km. Running the maths it produces 15.86 kg of CO2 per 100 km. Again its less than a fuel efficient car. I am hoping electric technology improves.
Thoughts on whether my "back of the envelope" calc is reasonably accurate. Is there anything I may have missed?