Many of the Chevrolet vehicles on the road have OnStar inside. This is the system that has been around for years that allows the driver to make phone calls and alerts emergency services in the event of an accident. That OnStar system will do other things too, and one of the other things is to help the Volt driver recharge their car with renewable energy.
OnStar is working with electricity provider PJM Interconnection and developing a technology that could give drivers the ability to choose what sort of power they want to use when they recharge. The drivers would choose their energy preference, and then the PJM company would look at the percentage of renewable power on the electrical grid and ensure that the Volt only charges using that power.
That doesn't make a lot of sense to me. For example, if you have power running through wires in a particular city with 80% coming from something like coal and 20% coming from wind or solar; how is it possible to ensure that only the wind or solar power generated is used for a Volt? The app will encourage the user to plug in when the renewable sources are at peak apparently rather than guaranteeing the driver is getting only renewable energy from what I can tell.