Yeah, the EV's are not zero emissions because almost all electricity involves some sort of pollution as well. Wind/solar/hydro are not a big enough part of the average american power grid to be relevant for a national discussion. But there are economies of scale in generating electricity in large plants, and the fact that the typical car charge would be done overnight at off-peak hours, helping the overall efficiency of the power grid.

Battery tech is really the key, and it's not yet ready for prime-time. Still expensive, still too short on range, but there have been some dramatic improvements compared to say the EV1 of the late 90's. The long charge time is especially limiting. Until a battery pack can hold enough charge for say 14-18hrs of driving (as much as most people would probably drive in a day without stopping to sleep/charge car) the EV would be unsuitable for the great cross country road trip.

In congested urban areas, say LA, where local emissions are a significant contributor to smog/poor air quality, the fact that the EV moves pollution to a remote location (power plant) has value in itself.

So I give the EV's of today their due as niche-market cars, but they are not suitable for most American drivers in their current form.