when will electric cars have common power supply for quick exchange?
Things like that have been talked about. More likely is that we will have batteries that can be charged quickly and charging stations.
Phoenix Motorcars has a battery made by Altairnano, which can be charged in 10 minutes with a special 440 volt charger. It's onboard 110 volt plug in charger takes 6 hours.
Another idea that has been discussed is for power companies to buy up used electric car batteries for storing energy. Apparently the batteries will have plenty of life left when they are no longer strong enough to run the car. This could conceivably reduce the up front cost of the car's battery as this would be pro rated, or discounted when the car is sold.
Electric cars are already sufficient for use as local delivery vehicles and such. Phoenix sees farmers and ranchers using their utility pickup as job trucks. Also, industrial, construction and mining sites could use them the same way.
I think plug in hybrid electrics, PHEV, are the best bet for the time being.
Plug in Partners has a lot of info.
Plug-In Hybrid Electric Vehicles (PHEVs) are outfitted with a battery pack sufficient to power the vehicle from 20 to 60 miles on battery charge alone. Considering that half the cars on America’s roads are driven 25 miles a day or less, a plug-in with a 25-mile range battery could eliminate gasoline use in the daily commute of millions of Americans. The cost of an equivalent electric gallon of gas is estimated to be less than $1.00."
"Gets about twice the fuel economy of a conventional vehicle and 30-50% better fuel economy than a standard hybrid
Plugs into a standard (120-volt) home electrical outlet to receive charge
Depending on design and battery size can be driven 20 to 60 miles without the use of gasoline "
"PHEVs outfitted with a battery pack providing a 40-mile electric range could power, using the all-electric mode, more than 60% of the total annual miles traveled by the average American driver."
And our electric grid, while not as clean as we would like it, is still much cleaner than using gasoline or diesel.
"Additionally, plug-in hybrids, like conventional hybrids, don’t idle when sitting still. Estimates are that in urban driving, idling translates to about 10%-15% of total vehicle carbon emissions."
"A motorist driving 9,000 annual gasoline-free miles and 3,000 using gasoline would get
100 mpg (based on vehicles that get 25 mpg)."