Petroleum refineries use a lot of electricity — the Argonne National Laboratory estimates that it takes about 6 kilowatt-hours of electricity per gallon of gasoline. Norby tacks on the electricity used for extraction, refining, and shipping and comes up with a “conservative” estimate of about 8 kwh per gallon. If that’s the case, then a gas-powered car that gets 22 miles per gallon would use about 40 kwh of electricity to go 100 miles. An average electric car, by contrast, would only use about 30 kwh of electricity to go the same distance. In other words, not only does the all-electric car use no gasoline — it would appear to use less electricity, too.
Now, admittedly, lots of electricity is produced with high pollution coal. But, the sources of power for the grid can be changed "painlessly" to the consumer in terms of lifestyle changes or new equipment. As long as the green contribution to the powergrid grows at least as fast as the marginal increase in electricity consumption attributable to electric car usage, coal consumption doesn't increase while petroleum consumption falls.
Once again, the only technological barriers to widespread use of electric cars appear to be a recharging infrastructure and batteries, and progress is being made on both fronts.