Large-scale battery storage is one of the newer storage solutions out there. And, researchers argue, is a far more plausible solution than other clean energy storage solutions of the past. For example, pumped hydro storage has been around since the early 20th century, but it has failed to prove itself to be functional or economical. In this type of storage, using the excess electricity from a turbine, water is pumped from a lower-altitude reservoir and stored in a higher altitude one. When the water flows back down through a turbine, it generates electricity.