How many gallons of gasoline would it take to charge an iPhone?

Re:How many gallons of gasoline would it take to charge an i... by frankus on Wednesday February 08, 2012 @12:27PM (#3567447)

Petroleum is really frickin' energy-dense (leaving aside the fact that unless you're heating something only a small fraction can be turned into useful work).

A mid-range home EV charger peaks out at about 20kW.

By contrast, the energy flux of a gas pump is around 20MW.

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Re:How many gallons of gasoline would it take to charge an i... by bhousel on Wednesday February 08, 2012 @12:54PM (#3567583)

A mid-range home EV charger (like the GE WattStation), is spec'ed for 30A at 240V, which is 7.2kW, not 20kW.

You might be confused because a typical battery in an EV is around 20+kWh, which is why it takes a few hours for the wall charger to charge it!

For comparison, a 20kW load would draw 83A at 240V. A smallish pole mounted utility transformer may supply 20kW.

Of course, none of it detracts from your point that petroleum is very energy dense :)

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Re:How many gallons of gasoline would it take to charge an i... by frankus on Wednesday February 08, 2012 @03:44PM (#3568390)

Good point. Most homes around here are wired with 200A, 240V power, so a 20kW charger would eat up about half of that.

So a 7.2kW charger is about 2500 times slower than a fast gas pump.

Even slow gas pump (say 10MW), used with a conventional engine (say 20% efficient), compared with a state-of-the-art fast charger (say 200kW) would still be ten times as fast in a miles-per-hour contest.

EVs make up for this somewhat by being able to charge anywhere that has a decent supply of electricity for hours at a time, but it still shows you what they're up against.

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