The addition of batteries as an intermittent power source brings us closer to 100% renewable energy and allows us to incrementally decommission dirty plants, such as coal- and oil-fired plants.

The design goal of adding a battery to grid power sources is to capture energy that would otherwise be lost when demand is lower than generation. In addition to capturing excess production of wind or solar-derived energy, one could capture unused energy from our current baseload generating plants overnight. We could also, this would also let us capture the energy that would otherwise be wasted by unnecessary nighttime lighting.