Finally Did It ...

It doesn't work like that, though. My utility has specific regular suppliers and when they need more electricity it is purchased from other specific suppliers, not some "national average". My increased consumption of clean electricity doesn't create a hole that has to be filled by "dirty" electricity.

 

Interconnected does not mean that new demand is satisfied with dirty electricity, even if tangentially.

 

When my demand increases by 1MWh per year to charge my PiP, my local utility has to ramp up production by that amount, or purchase it on the spot market if they don't have the capacity. They are in control of which plants supply that excess capacity. In my case those plants are solely wind and solar. I am not robbing some part of the grid of power that requires replacement with dirty coal. My demand is new demand being satisfied with new generation capacity.

Even if 100% of my power came from the dirtiest form of coal, the CO2 emissions for a 3kWh charge would be about 6.5 lbs. That's the equivalent of 1/3-gallon of gasoline. As long as I can drive 16 miles or further on a single charge, charging with 100% coal power is still a net decrease in CO2 emissions. According to the EIA only 38% of the power generated in 2013 so far has been from coal, so we're ahead of the game on average.

 

According to this article, PSE&G generated 85% of its electricity from nuclear and natural gas in 2011.

 

You can generate 16 kWh with natural gas for the same amount of CO2 as burning one gallon of gasoline. If you get 10 miles per charge with electricity generated from natural gas you're breaking even on CO2 emissions (and doing much better on a dozen other pollutants).