Electricity sources make electric cars carbon inefficient in SA

Submitted by: Margaret McKenzie, Monday, January 23, 2012

<p>Nissan Leaf at COP17</p>

Nissan Leaf at COP17

During COP17 last year a number of car manufacturers took the opportunity to promote electric vehicles as a method of reducing carbon emissions.  Vehicles on display included the South African developed Joule, and even an electric motor bike and electric Porsche from Siemens.  The electric vehicle that is likely to reach the South Africa market first is the Nissan Leaf which is expected in 2013.


One of the key features of marketing of electric vehicles is a “Zero Emissions” claim.  However, while electric vehicles may not have the direct emissions of conventional cars, they indirectly produce emissions through the electricity they use.  The level of emissions released depends on the source of energy used in the electricity generation process.   For instance, if an electric vehicle is charged from a solar PV panel then there will be no emissions from electricity generation. However, if an electric vehicle is charged from the South African grid, then there are indirect emissions as a result of the coal powered electricity generation process.

Unfortunately, the South African coal dominated electricity generation process means that a relatively high amount of carbon dioxide is released in the electricity generation process.  As a result electric vehicles indirectly release more greenhouse gases (GHG) when compared to some of their petrol competitors.  The graph below compares the greenhouse gas (GHG) emissions associated with a VW Polo 1.4 Trendline, a Nissan Leaf and a Toyota Prius Advanced.  Details of the sources used to make the calculations in this graph are shown in the table at the bottom of the article.

While electric vehicles might be carbon inefficient in SA, the current petrol and electricity pricing in South Africa means that they are likely to be at least 50% more economical than some of their efficient petrol competitors.   The graph below compares the Rand cost of driving the Nissan leaf against the same two petrol cars.

Sources used:

  Efficiency Conversion Factor kgs C02e per 100 km Rand per unit Cost per 100km
VW Polo 1.4 Trendline 6.1 litres per 100 km (VW Website) 2.3117 kgs of C02e per litre of petrol (Defra) 14.10 R10.31 per litre (current unleaded petrol price Durban) R62.89
Nissan Leaf 17.3 kWh per 100km (Supplied by Nissan) 0.99 kgs of C02e per kWh (Eskom Integrated Report 2011) 17.13 R1.07 (current cost per kWh of electricity in Durban) R18.51
Toyota Prius Advanced 4.2 litres per 100 km (Toyota Website) 2.3117 kgs of C02e per litre of petrol Defra) 9.71 R10.31 per litre (current unleaded petrol price Durban) R43.30


Margaret McKenzie