Australasian Science: Australia's authority on science since 1938

The Basic Mistake Made by Critics of Electric Vehicles

Credit: Francois Poirier/Adobe

Credit: Francois Poirier/Adobe

By David Richardson

Arguments that electric vehicles are no “greener” than the electricity they use fail to acknowledge the increasing role of renewables in the energy grid.

In most countries, motor vehicles are a major source of pollution, and the obvious response is to promote electric vehicles. However, critics respond that electric vehicles use electricity from dirty sources so their operation may not be emissions-free after all.

A large electric vehicle charged in an area using coal-fired electricity generators may appear to have worse emissions than a small fuel-efficient internal combustion motor vehicle. For example, there are claims that a Tesla charged at the national average greenhouse intensity of the Australian grid emits twice as much as greenhouse gas as a Toyota Prius hybrid vehicle. It has been argued that Australia needs to get its average emissions intensity down to 700 g/kWh or less before emissions due to electric vehicles are better than the internal combustion vehicle.

The critics point to the average emissions intensity of power plants in a particular region, and say this shows how polluting electric vehicles might be. Even the supporters of electric vehicles accept the basic argument but suggest the claims of the critics are too high, so there is an argument about the exact figures. But the argument is flawed and the reason is rather simple.

In swapping internal combustion vehicles for electric we obviously reduce the on-board emissions of the vehicles. That is not in dispute. However, that swapping also increases the demand for electricity, and it is important to consider how supply is responding to increases in demand.

At the moment, renewables are replacing fossil fuels in power generation (albeit too slowly), and it is renewables meeting the increases in electricity demand. Therefore it is irrelevant to compare new electric vehicles with the average emissions intensity of the electricity grid. New demands for electricity from electric vehicles need to be compared with the new facilities that are and will match that new demand.

An example can reinforce the point. Suppose I buy an electric vehicle to replace my internal combustion vehicle, and I install solar panels on my roof to charge the vehicle. In that case it is unambiguous – there is a clear reduction in emissions. That is easy to see, but what if instead I continue to rely on the grid and my electricity provider installs additional solar panels to meet my additional requirements to run the electric vehicle. The result is exactly the same.

To suggest that electric vehicles will pollute at the average emissions intensity of the electricity they use is to suggest that somehow they will cause additional emissions. That implicitly assumes that the average emissions intensity and the emissions from the incremental supply response are the same. But clearly an increase in demand for electricity cannot increase the emissions from fossil fuel generators if fossil fuel generation capacity is constant or indeed declining.

Data from the Australian Energy Regulator clearly show that since 2012–13 there have been reductions in coal-fired capacity while there have been increases in solar, wind and gas. The additions in gas are less than the reductions in coal, so fossil fuel generation has fallen as a whole. These trends are expected to continue, and official projections suggest that future new capacity will also be dominated by renewables. So the incremental electricity response is green, and it is nothing like the average emissions intensity.

As far as we are aware our argument is novel, but as soon as it is pointed out people immediately “get it”. But until they get it people are tempted to confuse averages with increments.

We would prefer to see a much more rapid phasing out of fossil fuels, but in the meantime any switch away from fossil fuels towards electricity in transport will raise the demand for electricity. Increasingly that additional demand has been met by renewables, and that is likely to continue.


David Richardson is Senior Research Fellow at The Australia Institute.