Five hours with a 220V circuit drawing 50A, even with charging losses, which are much lower charging a capacitor than they are with batteries.
So you could recharge at home overnight easily.
The five-minute recharge would be done at a “gas station” and transferring from the station’s own bank of capacitors to your vehicle at very high voltages and low amperage. Low amperage means small cables, not “as thick as your arm” as someone else suggested.
The bottleneck would become the electrical service to the stations. To recharge 500 vehicles per day would require 50kwh x 500 = 25mwh per day. 25mwh / 24 hour per day means an average draw from the grid at 480V of 2000A. That one service station would be drawing as much power as 1000 homes.
That’s assuming 50kwh will power a car 500 miles.
“The bottleneck would become the electrical service to the stations. To recharge 500 vehicles per day would require 50kwh x 500 = 25mwh per day. 25mwh / 24 hour per day means an average draw from the grid at 480V of 2000A. That one service station would be drawing as much power as 1000 homes.”
Hey, I hadn’t run those calculations before. I used to do some stuff with the nuclear energy and debated the enviros all the time who were into the hydrogen economy. Many problems there as well. Nothing like hydrocarbon to pack energy for easy transport.
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Actually, While your numbers are the best I have seen so far there are a couple of other realities to consider. Most electricity at the neighborhood level is either at 5000V or 13000V. If you go to the next step it is at 69000V. We have transformers in various locations to get it down to 480V, but it would be easy to supply 5000V. Large facilities like large buildings often use 5000V motors to operate airconditioning equipment. This makes the cable quite small and the insulation around it quite large.
If the energy supply station had it’s own bank of capacitors it could be charging continuously then they could do an instant transfer at very high voltage to cars that came in for a refill. 50000W @ 5000V is only 10 amps, at 13000V it is only 3.8A and at 69000V is only .72A.
There is nothing impossible here once the right materials have been found. Some day all our cell phones, PDA’s Ipod’s etc will be charged with a coil that will charge a supercapacitor as we walk around near charging stations.
As far as charging overnight, I suspect that we will have a supercapacitor at home charging while we are away and when we get home it will dump a full charge to our car in a matter of seconds.
If this works there will be many type of alterternative energy that will be practical especially photovoltaics, windpower and wave power.