Will EVs reduce our carbon emissions if we don't change behaviour?

Summary

My last post outlined my idea that switching ICEVs (petrol cars) for EVs (electric cars) is not sufficient to prevent climate change. I wanted to find a different way to illustrate this, so I created a simple mind-sized model. You can download the model and play with it yourself, and form your own conclusions. The model shows that if all new cars bought in Australia are EVs, it is not sufficient to prevent serious climate change if we maintain current patterns of car ownership and use.

If you are buying a new car anyway, it will be less harmful if it is an EV and not an ICEV. However, the best outcome is to retain your existing ICEV car and simply drive it less -- make more use of walking, cycling and public transport instead. Get an ebike or a scooter/moped. This has the added benefit of saving you a lot of money and improving your fitness.

The model

You can download the model here. I've saved it in an Excel spreadsheet for maximum compatibility. If you don't have Microsoft Excel (good on you!) you can open it using LibreOffice, which is a free Office program that runs on all computers. The following assumptions outline my thinking in the model -- these numbers are all adjustable in the model, so if you disagree with my assumptions you can try tweaking them. 

1. There are 20 million cars in Australia, the total number of cars grows at 1% annually
2. There are 1 million new cars bought in Australia each year
3. The embodied CO2 emissions in a new ICEV and new EV are 16.3 and 26.9 tons respectively (as described by Volvo in their article)
4. The average Australian car drives 12000 km / year
5. An EV emits 20g / km of CO2 at point of use
6. An ICEV emits 200g / km of CO2 at point of use

Based on these assumptions, I ran two scenarios:

• Scenario 1: every new car in Australia is an ICEV
• Scenario 2: every new car in Australia is an EV

I examined how these two scenarios compare out to 2040, in terms of cumulative CO2 emissions. Below is a graph that shows how cumulative emissions compare under the two scenarios:

Observations:

• by 2040, the all-EV scenario has CO2 emissions that are 16% lower than the all-ICEV scenario
• In both scenarios, cumulative CO2 emissions are above 1 Gt (billion tons) 
• After 2040, in the all-new-EV scenario, almost all cars in Australia would be EVs. If we stopped buying new cars altogether at this point, additional CO2 emissions in the all-EV scenario would be very small
• our carbon budget is 1.3 gigatons if we want to remain below 1.5℃ of warming. We have pretty much exhausted this budget just on EVs and have nothing left for decarbonising all other aspects of the economy (in other words, we will hugely overshoot our budget, with consequent climate instability)
• A significant limitation to the model is that not all cars in Australia drive the same amount. If we prioritised changing the highest emitting (furthest driving) cars to EVs, it would have a more significant effect than observed in this model.

Variations to the model

I tried some variants to see what would happen:

• reducing the EV point-of-use emissions to 0 g/km doesn't significantly change the results
• increasing the rate of EV adoption to 4 million new EVs / year reduces the total CO2 emissions at 2040 to 0.8 gigatons.
• setting annual growth in total car numbers to 0 doesn't significantly change the results

Conclusion

1. We cannot keep driving petrol cars like we do now and maintain a safe climate
2. EVs are better than petrol cars in that they emit considerably less CO2 at time of use
3. However, the additional CO2 emitted when manufacturing EVs (compared to ICEVs, which is already considerable) means it takes a long time (approximately 20 years) to achieve emissions-reduction by simply buying new EVs. During that time, we will exceed our carbon budget.

I know this is bad news, and that people won't want to hear it. I'm not happy about it either.