Electric vehicles are being hailed as eco-friendly alternatives to the petrol and diesel vehicles most of us drive.
One thing many seem to forget is that South Africa’s electricity is predominately generated by coal-fired power stations.
Coal power is environmentally unfriendly, spewing large volumes of pollutants and carbon dioxide into the atmosphere.
So when you plug in your electric car to recharge, it is not a cleaner, “zero-carbon emissions” alternative to petrol and diesel cars.
South Africa’s energy mix
To determine the carbon dioxide (CO2) emissions produced when an electric car is plugged into the South African electricity network, we must look at how much CO2 is being produced by our power stations.
Our power generation mix is detailed in the 2013 (non-promulgated) Integrated Resource Plan (IRP), while the CO2 emissions data is contained in the Eskom 2016 Integrated Report.
The graph below shows that the amount of electricity generated by coal power will level out from about 2027, while the percentage of non-carbon emitting power gradually increases.
It shows that carbon emissions produced by South Africa gradually reduce over time until they level out in about 2047.
CO2 emissions in South Africa: day vs night
One can argue that the graph is not a true reflection of carbon emissions, though.
During the day, there are times when the percentage of non-CO2 emitting power stations that are online are higher.
For example, solar power will be online during daylight hours, which would suggest that daytime carbon emissions per unit of energy produced will be lower than during the night.
The graph below shows the effect the time of day has on carbon emissions produced.
If you have an electric vehicle you want to charge from the national grid, it would be best to plug it in during daylight hours when CO2 emissions are lower.
The graph also shows that from now until about 2025, one can expect an electric car’s “CO2 emissions” to be bad, but that from about 2020 onward it should improve significantly.
CO2 emissions of electric vehicles charged during the day
However, the improvement is not great when compared with other vehicles currently on our roads.
The most eco-friendly electric car to drive is the BMW i3 (without the range extender), but only on condition it is recharged during daylight hours.
Even if this is done, it will only start to “emit” less CO2 than diesel cars from about 2026, and only if we assume that no improvements are made in reducing the carbon emissions of diesel vehicles.
CO2 emissions of electric vehicles charged during the night
We can also assume that most South Africans will only be able to plug in and recharge their electric vehicles at night when the car is parked at home.
The graph below shows that the emissions are then much higher, and that the BMW i3 will only start producing less carbon “emissions” than diesel vehicles by 2029.
The Nissan LEAF performs worse than some petrol vehicles, while the Tesla Model S 70D performs the worst overall.
Therefore, your daily commute will actually be more environmentally friendly if you choose to drive a diesel vehicle as opposed to a plug-in electric car, assuming that:
- Petrol and diesel vehicle manufacturers report carbon emissions of their vehicles accurately.
- South Africa’s power generation mix will grow as envisioned in the 2013 IRP.
- Electric vehicle owners are restricted to recharging their vehicles by plugging them into the South African grid network.