The second-biggest form of bulk-energy storage, though it is dwarfed by PSH, is compressed-air energy storage (CAES).

ECONOMIST: Energy storage

At the moment, however, there are only two compressed-air energy-storage plants in the world (one in America and one in Germany), and neither was built to make use of wind power.

ECONOMIST: Compressed air might help to make wind power more reliable

In addition to nukes, OR-SAGE also examines advanced coal with carbon capture and storage, solar and compressed air energy power plants.

FORBES: Plotting The Next-Generation U.S. Power Grid