My town provides this option - including various shades of green energy. We're currently on "100% green" but like 40% from burning garbage at the landfill for power generation. This year they gave the option to do entirely solar but I haven't gotten around to it yet.

I'll admit I don't know much about how they allocate power (sourcing or distribution). I always figured my electricity was coming from the same pool as my neighbors regardless of the sourcing I was paying for, but if I can encourage my town to switch to green energy faster, that seems worth doing.