Storing excess renewable resources, such as solar and wind, is vital in securing an energy-efficient future. To understand just how vital energy storage is, consider this. Fossil fuel, such as coal and oil, are forms of stored energy, always ready when society needs it. Solar and wind are forms of “real” energy, coming and going irregularly. If we want to replace the value that fossil fuels afford our society, we have no choice but to add storage to intermittent renewable energy to make it readily available.