Hypothetically, let's say you can charge at 120 kW and you need 25 spots to handle peak demand of 50 cars/hour (each charge takes 30 minutes) with a peak demand of 3 MW.

Now you have cars that can charge at 1 MW and you have 3 stations so your peak demand is still 3 MW.

In both situations your peak demand will still be the same - 50 cars/hour, 60 kWh per charge, 3 MWh, but you will need more stations and sports to support the slower charge rate.

But in the real world, utilization will be lower for the 3 1-MW station setup because inevitably a greater percentage of time time will be spent moving cars instead of charging cars as it takes a constant amount of time to park/start/stop/move regardless of how fast one can charge.

Yeah, I agree - 250 kW is fast enough for majority of uses. The 2 MW calc was really just an exercise to show how fast charging would need to be to match the charge rate of gasoline...

Really, the only possible way to do that today is with battery swap, but then it's not really charging, is it?

Yep, all good points.

But of course, faster charging is also expensive. Right now superchargers charge at 90 kW, but Tesla has always planned on bumping that up to 120 kW, so it's quite possible that they are simply announcing 120 kW supercharging capability, though that is still far short of how fast one can pump gas.

If one assumes that you can only pump gas at 5 gallons/min (pumps can go up to 10 gpm), that's 300 gallons/hour. Filling a 19 mpg car (MB S600 hwy), that's the equivalent of charging at 5,700 mph.

Now assuming that the Tesla goes 100 miles on 38 kWh, so at 120 kW that's charging at only 316 mph - to match the the fill rate of gasoline, you'd have to charge nearly 20 times faster, or around 2 MW.

That's a LOT of power!

Nice interview except for the snipe against California ZEV credits / regulations.

Without those regulations, Tesla would not exist today. One of the big reasons they still exist is because they generated a lot of revenue selling ZEV credits.

If you want to see the charger, Green Car Congress has some pics and more technical details: http://www.greencarcongress.com/2013/04/c30-20130423.html

San Francisco also has a good number of similar electric buses.

The vast majority of companies out there now, can't be bothered to install any EVSEs because of the upfront cost to install these stations and the ongoing cost to maintain said infrastructure.

In the area I work right now (I'm in southern California, a supposed EV/plug-in mecca), the closest EVSEs are over a mile away at a Walmart and Walgreens.

The closest workspace charging locations I see are over 5 miles away. In a 10 mile radius from here there are maybe a handful of businesses with charging on site.

And this is in an are where public charging infrastructure has been pushed for 2 years now.

Showing businesses that they at least have a chance of recouping at least the ongoing cost of installing EVSEs is a good thing.

You are forgetting (like most people) that providing charging infrastructure also costs money. Many businesses or municipalities would love to install charging stations, but they must at least hold some glimmer of paying for itself.

A commercial grade EVSE will cost at least $2,000 for the hardware. The install can very easily cost at least 5 times that due to the cost of trenching required to install them.

So let's say one is able to install 10 EVSEs for the bargain price of $30k ($20k hardware, $10k to install them) or $3k / each. At a $0.10/kWh profit, it will take 30,000 kWh sold to break even. If the station sells 10 kWh / day, it's going to take 8+ years to break even assuming that the EVSE does not require maintenance.

I have to think that there is some ramp from "too cold can't charge at all must warm the pack" to "it's pretty cold, can only charge at 5 kW" to "pack warm, can charge at 90 kW".

In the middle there the car might charge as fast as it can (which will heat up the pack on it's own) and use any spare power to heat the pack up faster.

I bet you could monitor this by looking at the dash when charging - the miles/hour charge rate should start low and then start climbing as the pack warms up while the volts/amps reading stays constant.

If you really want to change it - it should be Wh/mile (or kWh/100-mi as Tim Meyer suggests), not mi/kWh or MPGe.