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Re:How many gallons of gasoline would it take to charge an i... by teamonkey on Wednesday February 08, 2012 @01:02PM (#3567623)
Oil power stations are around 33% efficient[1]. Electric drives have up to 80% efficiency[2].

Given those rough figures, even when powered by oil stations battery-powered cars can theoretically be more efficient at using oil than a car with an ICE.

[1]http://en.wikipedia.org/wiki/Oil_power_plant#Heat_into_mecha...

[2] http://en.wikipedia.org/wiki/Electric_car#Energy_efficiency

Re:How many gallons of gasoline would it take to charge an i... by gvb on Wednesday February 08, 2012 @02:18PM (#3567983)
You also need to account for the transmission line efficiency[1], the charger efficiency (typically 90-95%), and battery efficiency[2] (80-90%).

If we assume the transmission lines are 98% efficient, the charger is 95% efficient and the battery is 90% efficient, the motor controller is 95% efficient, and the motor is 95% efficient (drive efficiency of 90% instead of 80% of the parent quote)...

0.33 * 0.98 * 0.95 * 0.90 * 0.95 * 0.95 = 25% efficient, with efficiency numbers somewhere between "best case" and "optimistic". ICE in an efficient car is competitive with that. A hybrid will beat that.

[0] How Stuff Works estimate: http://auto.howstuffworks.com/fuel-efficiency/alternative-fu...

[1] Nobody knows for sure what the transmission line (including step-up and step-down transformers) is in actual practice. Note the Wikipedia article says "efficiency" several times, but never pins an estimate onto it: http://en.wikipedia.org/wiki/Electric_power_transmission

[2] http://en.wikipedia.org/wiki/Lithium-ion_battery

Re:How many gallons of gasoline would it take to charge an i... by colanderman on Wednesday February 08, 2012 @01:16PM (#3567688)
Not disagreeing with you, but the point of an electric car is not drivetrain efficiency. It's regenerative braking and emission consolidation.
Re:How many gallons of gasoline would it take to charge an i... by rdtsc on Wednesday February 08, 2012 @02:00PM (#3567899)
However does the efficiency offset the inefficiency (physical and economic) to store enough electricity to make it feasible.