We have two options: 2.4¢ additional per kWh for the Green Start program, or 3.8¢ for the Mass Wind program.
https://www.massenergy.org/renewable-energy
We are paying (with NStar) 19.2¢ / kWh already. And that price is likely to go up by as much as 37% this winter.
On Forest (our new Leaf) it cost us 5.1¢ / mile which is less than a Prius - at 6.4¢ / mile at the current local $3.199 price for gas @ 50MPG.
I charged Forest last night - 16.17kWh and drove 68.5 miles = 4.236 miles / kWh = 142MPGe. At our current electricity rate plus the Green Start cost, that makes it ~$7.279 / gallon equivalent. Again that is 5.1¢ / mile.
It makes a solar PV system look even better!