Electric cars, quantitatively.

For argument’s sake, I’ll start with an assumption that the fuel economy of your average petrol-fuelled ICE passenger car is about 7 L per 100 km under conventional conditions.

7 L / 100 km corresponds to about 15.1 kg carbon dioxide emissions per 100 km.

(You can use the above expression in Google Calculator, and just substitute in any alternative figure for the fuel consumption for your particular car, if you like.)

(In the above calculation I’ve used the assumption that petrol is basically pure n-octane in chemistry terms, in terms of its density and carbon content.)

Obviously, better fuel economy means better CO2 emissions economy and vice versa.

(For readers in the US (or elsewhere) who would prefer the Imperial units, try this link instead. Fuel economy of 30 MPG will correspond to about 0.6 pounds of carbon dioxide per mile.

The Blade Runner Mk. II BEV, for example, (which you can buy in Australia now), requires a charge of 95 amp-hours at 240 V, and has a range of 120 km, corresponding to an electric power consumption of 190 Wh (Watt-hours) per km.

(Similarly, if we know the charger’s current draw, voltage, charge time, and the vehicle’s operating range for a single charge, then the electrical energy required to run the car for a given range is straightforwardly calculated for any EV.)

The tech specs for the Tesla Roadster claim that its electric power consumption is 110 Wh/km.

The specifications for the Mitsubishi i-MiEV correspond to about 154 Wh/km average.

In Australia, the average GHG emissions intensity for electricity generation is 1000 gCO2/kWh. (In Victoria, it’s obscene, about 1300-1400 gCO2/kWh.)

Therefore, the equivalent CO2 emission for the BladeRunner is 19 kg CO2 per 100 km, for the i-MiEV it’s about 15.4 kg / 100 km, and for the Tesla Roadster it’s about 11 kg CO2/100 km.

So, for electricity generation like Australia’s, the i-MiEV is about the same, in terms of its indirect greenhouse gas emissions intensity, as an average, reasonably fuel efficient, petrol-burning ICE car. The BladeRunner is significantly worse than an ordinary car, and the Tesla Roadster is significantly better – but I guess the Tesla represents what is essentially a top-of-the-line EV, with a price tag to match.

At the moment, in Australia, there is absolutely nothing to be gained at all, in terms of greenhouse gas emissions reduction, from electric vehicles. (Unless you get a Tesla). (In fact, choosing an EV over a new, relatively efficient petrol or LPG fuelled conventional ICE vehicle, which you could easily get for the same kind of budget, could very well represent a significantly worse choice, in terms of GHG emissions.) For that to change, what is required is a large reduction in the greenhouse gas intensity of electricity generation – replacing coal-fired generators with nuclear power or other clean electricity generation.

However, the greenhouse gas intensity of Australia’s electricity supply is very bad, by global standards. Ontario (in Canada) is an example of a place where extensive uptake of nuclear power, and extensive access to hydroelectricity, have almost completely displaced coal-fired generation, and provide electricity with extremely low greenhouse gas emissions intensity – about 200 gCO2/kWh, or 20% of the Australian average. In Sweden or France for example, you’ll see much the same.
In the US, for example, on the average, it is somewhere in between.

Thus, under these conditions, the BladeRunner has equivalent GHG emissions of about 3.8 kg CO2 per 100 km, 3.1 kg/100 km for the i-MiEV, and about 2.2 kg/100 km for the Tesla – all of which are far superior to any ICE vehicle.

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