The Extinction of the Internal Combustion Engine

Internal combustion engines (ICE) are going extinct and will be replaced by the brushless electric motor.

These metrics encapsulate why:

Metric	ICE Motor	Electric Motor	Conclusion
Power to Volume	0.4 kW/L	13.6 kW/L	Electric motors are 40x smaller
Power to Weight	1-3 kW/kg	3-10 kW/kg	Electric motors are at least 3x more powerful
Efficiency	5-30%	90-96%	Electric motors are 2-20x more efficient
Maintenance	Hundreds of moving parts	One moving part	Electric motors are almost maintenance free

Why then have we used ICE motors for the last 100+ years?

The answer is the energy density of fossil fuels. Take petrol (gasoline) for example, which has a whopping 12,000 Whr/kg of energy, 50 times more energy density than today’s best batteries.

In 1900, electric motors and ICE motors were competing technologies but at that time lead-acid batteries were 10 Whrs/kg. To travel 500km with that measly energy density would require the mass of an elephant (10 tonnes) worth of batteries. Today’s lead-acid batteries are 30 Whrs/kg, so that same journey could be achieved with a Rhinoceros (3 tonnes) worth of batteries and modern lithium batteries (250 Whr/kg) only require a gorilla (400 kg) worth of batteries. This remains much less than petrol but in conjuction with the advantages of the electric motor the battery electric vehicle can outperform ICE vehicles. And it’s not over yet, battery technology is rapidly evolving.

Battery energy density will likely never achieve that of fossil fuels but combined with the superiority of the electric motor it does not have to.

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Reference: TU-Delft – Electric Cars: Technology – Lecture Notes 1.1