When marketing campaigns get involved playing nice music and trying to make people feel good about spending tens of thousands on the latest technology. How good actually is it? Importantly, how much CO2 is produced when you drive your electric car down the road?

This depends on a few things, the major ones being how far can you get on a KWh (Kilowatt Hour) of electricity and how much CO2 is produced to make that KWh of electricity at the power station?

How far on one KWh?

The average electric car can travel 100 miles on 34.6 KWh (Average Electric Car kWh Per Mile [Results From 231 EVs] (ecocostsavings.com))

That is 160Km on 34.6 KWh. So 160 divide by 34.6 gives 4.62 km on 1 KWh on average or 0.21625 KWh to do 1 km.

How much CO2 is produced to create 1 KWh of electricity?

40% of the worlds carbon emissions are from electricity production.

But actual emissions vary from country to country. Countries like the USA where 40% of the electricity is from coal, will be higher than the UK which burns hardly any coal.

I have picked one figure for the purpose of this blog post that is 309g of CO2 to produce a KWh of electricity (Emissions from home energy use (carbonindependent.org)).

How much to travel 1 km?

0.21625 times by 309g = 66g of CO2 to do 1km in an average electric car.

This means a petrol car doing 50mpg can produce 120g/km, lets say approximately an average electric car is doing the equivalent of 100 miles to the gallon.

There are other factors that I haven’t been able to work out accurately, such as:-

• Voltage losses in the electricity network. Is the 309g an accurate figure for electricity actually coming out of the wall socket, or is this the figure at the power station? There could be a 20% discrepancy here.
• Actual consumption figures from the car in cold weather, again range could be reduced by 10 or 20%.
• Batteries take more energy to charge in cold weather and lose their capacity quicker.
• Heating lights and windscreen wipers etc, reduce the range.
• Some electric cars are very powerful, although making use of this performance will have a significant effect on the range, just like it does with a petrol car.

I have said the average electric car does 100mpg equivalent but is the reality a lot less? If all of the above factors are taken into account, then it could be closer to 50mpg, or over 100g of CO2 per km just like petrol or diesel cars.

The inspiration for this post came from another post I made about an hybrid Nissan. It produces 119g/km of CO2, which is very close to the Mercedes E220 coupe that I bought in 2012. This is a 2 litre diesel that would do 600 miles (50mpg+) on a tank of diesel.

So, if the driver is really serious about emissions, then its probably best not to buy an electric car, buy an older smaller petrol car instead, do less miles and put even just 100 a month towards green initiatives such as planting trees would be a much better idea. Much better than driving your new electric car thinking you are making a difference. Truth is, you are not.