EV mythbusting – renewable vs fossil fuelled power

This story first appeared in the April issue of AutoTalk – CLICK HERE to download the magazine FREE

For a long time, I’ve worked on the conventional wisdom that EVs make sense in places where power is produced by renewable sources, but not so much in places that use large amounts of fossil fuels.

I recently decided to find out if this was true.

A common argument is that since EVs draw power from the local grid, they are in essence powered by whatever means of power generation is locally available.

Some jurisdictions, like Norway with 100% renewable power generation (and New Zealand at over 80%), would therefore be much more suited to EVs than other countries; including Australia, which until recently used fossil fuels (mostly coal) to generate almost 80% of its power.

No one would argue that powering a car with coal is a good idea for the environment.

Hence, EVs were argued to be unsuitable for use in Australia.
Hybrids and other vehicles with efficient internal combustion engines were said to be the better option, assuming reducing emissions is our primary concern.

Initially this sounded logical to me.

However, I wanted to make sure we were comparing apples with apples, so I stepped back and rethought the problem.

EVs produce zero emissions while driving, while the average petrol-powered car emits 118.5 grams of CO2 per kilometre.

If we want to quantify the emissions of producing the EV’s power, then to be fair, we also need to consider the emissions produced in refining the petrol to drive the car.

This, it turned out, was not easy to find, as oil companies stopped reporting this information in the early 2000s.

In 2005, it was estimated that the power cost of producing a litre of oil was between 1kWh and 2kWh.

While this number has been debated, it has not been officially refuted by the oil industry in the years since.

When using coal, one of the dirtiest modes of electricity production, 940 grams of CO2 are generated per kWh.So, to refine just a litre of petrol, around 1000 grams of CO2 is produced.

Returning to our average petrol-powered vehicle, with a fuel efficiency of 8.9 L/100km; driving that 100km would consume 8.9L of petrol, producing 20,000 grams of CO2.

The refining of that petrol would have produced 8900 grams of CO2.
The total cost of driving our average petrol-powered vehicle 100km would be around 28,900 grams of CO2.

The EV, on the other hand, produces no emissions while driving, and takes all its power from the same coal-powered grid.

The average EV has an efficiency of around 19.1kWh/100km (and this also happens to be the efficiency of most Nissan Leafs).

Driving that same 100km the EV would therefore produce a net 19,100 grams of CO2.

Initially I tried to also compare the best hybrid, but I ran into the problem of not being able to quantify when the vehicle was in EV mode and when it was in petrol mode.

The best I could find was estimated averages of approximately 4.3 L/100km for a new hybrid.

When I did the same calculation with those numbers, the hybrid did appear to fare better in the pure coal-powered environment, and in Australia.

What I realised, however, was that the averages had nothing to do with the way the vehicle actually worked.

While that 4.3L/100km might be the average petrol efficiency, it is a trick of numbers.

In reality, the vehicle operated as an EV for the first 100km, then as a petrol vehicle after that.

This leaves the EV as the winner in every case, even in places that rely entirely upon fossil fuels for power production.

There is one last point I want to make about petrol vehicles.

While we included rough estimates of the cost of refining, I did not factor in the cost of oil extraction or transportation, nor did I factor in the cost of petrol distribution.

Some estimates I saw suggest the sum of these other activities would add at least 50% to the values used for refining, and the balance is likely to be tipped further by a clean power grid.

Overall, I am going to call that one debunked.