Why are electric cars more environmentally friendly than petrol cars?

With Tesla announcing the production of the model 3 and Volvo recently announcing that petrol engine cars won’t be produced beyond 2019, it seems that there is an inexorable trend towards electric vehicles. But why are electric vehicles superior to internal combustion engines in energy efficiency and therefore their environmental friendliness?

On the surface, it seems obvious that electric cars emit no gases from an exhaust pipe and therefore avoid polluting the environment. However, in the ignorance of my youth, I thought that electric cars would not improve the condition of the environment because under the conditions of the present electric grid, they were essentially coal powered cars. However, from an emissions perspective it is actually still more efficient than the world being powered by petrol. The main reason for this difference is the heat dissipation of the two types of engines. The maximum amount of energy from a petrol fuel tank that can be converted into kinetic energy is about 50% from the most efficient engines. By comparison, electric motors can achieve 90% or more conversion of the energy inputted into them.

In addition to this coal fired power stations achieve some efficiencies from the scale at which energy is produced in comparison to the burning of petrol. There are some losses of efficiency from the transmission of power in the grid but this is more than offset by the energy efficiency of electric motors and the efficiency gains from coal fired mass production. Also, eventually the grid will become renewables based as this is the trend of investment in energy infrastructure.

The development of electric cars is also important because of the improvements in battery technology and battery production which result from the development of electric cars. Mass production of advanced batteries is needed to make renewable energy sources like solar and wind viable as a source of baseload power. This is because solar power is only produced during the day and the energy produced must therefore be stored until the peak load period at night. In the case of wind power, as periods of windiness are unpredictable it is also necessary to store the energy produced until when it is needed. The mass production techniques and infrastructure for lithium ion batteries being developed and used for electric cars also supports the development of renewable energy sources.

One criticism of electric vehicles is that the mining of the lithium used to produce the batteries which power electric cars is a very environmentally destructive process. It can create serious soil toxicity issues. However, battery recycling and sustainable mining techniques under development appear to be able to address this problem. So, in the final analysis, it is true that electric vehicles are more environmentally friendly than internal combustion engines.

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