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Thursday, February 3, 2011

Suck, squeeze, bang, bust: The end of the ICE?

Tim Stevens over at Engadget has written a post today about the death of the internal combustion engine (ICE), using cigarette smoking as a example of how trends can change.

Good to see the 'word' is finally getting out about the gross inefficiency of ICEs. The information referenced by Tim is actually fairly conservative as he's quoting 30% energy efficiency for petrol fueled ICEs but that is when measured at the flywheel. The real figure for an ICE vehicle is closer to just 15% total energy efficiency when measured at the wheels.

Yet even that may be over-stating energy efficiency as much of the remaining 15% used to get the vehicle rolling is also converted into waste heat when braking.

With an electric motor, most of which are 90+% efficient, energy converted into inertia when accelerating a vehicle can be regenerated during braking and reused in the next acceleration cycle.

In some cases, such as in urban stop-start traffic, regen can extend battery range by as much as 50%. This brake regeneration is the principle used in all hybrids to improve overall vehicle fuel efficiency, although it does absolutely nothing to improve ICE inefficiency.

Due to the fundamental energy efficiency of electric motors in both propulsion and braking, the ICE-less Nissan Leaf can to be equipped with a battery having a maximum energy capacity equivalent to only 0.65 US Gallon (approx 2.5 liters) of gasoline, yet still have the torque of a V6 and 100 miles (160 kms) range. If the ICE version of the Leaf (the Versa) had the same sized fuel tank it would barley cover 20 miles.

In the same way incandescent light bulbs are now banned for sale in countries like Australia, based on the fact that they convert 95% of the energy they consume into waste heat, for that reason alone (and there are PLENTY of other valid reasons), it would seem the shift away from ICEs and towards EVs is inevitable.

Source: Engadget

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