Plug-in cars are the future. The grid isn’t ready.

It is not a problem specific to New York state. Similar constraints exist in Texas, California, Maryland, Illinois and elsewhere. Across the country, long-distance transmission lines can only carry so much electricity, just the way a pipe can only carry so much water. When they’re at full capacity, they can’t carry any more, even if a downstream customer — a local utility, for instance — is trying to obtain some.

Source: WP