EERE: Power - Energy Storage - U. S. Department of Energy site with short summaries of compressed air energy storage, superconducting magnet E. S., flywheels, pumped hydro, Utility Battery Storage (UBS) and supercapacitors.
Electricity Storage Association - "A non-profit trade association bringing electricity storage solutions to the power industry" links to a tutorial on Energy Storage Technologies
Energy Storage - Information on Energy Storage, including history. Highlights thermal storage. From the U. of Rochester District Energy Library.
Energy Storage: General - Queensland Government page with information on energy storage technologies. Includes diagrams of regenerative fuel cells, compensated (constant volume) and uncompensated (constant pressure) compressed air, batteries, and pumped hydro.
Energy Storage Council - Group of industries and developers to advocate and facilitate the deployment of energy storage technologies. Links to pages of 6 charter members and 2 newer members.
Flywheels and Compressed Air - Page from a series of lecture notes; discusses flywheels and compares them to compressed air for energy storage. Includes formulae to calculate energy stored.
Physical Limits of Portable Power Storage - Comparison of 4 options: flywheels, compressed air, ultracapacitors, fuel cells, posted by MIT Media Lab in 1999. Engineers and physicists may question some aspects of the analysis.
TVA: Fail-Safe Power - Page highlighting Tennessee Valley Authority (U. S.) use of Superconducting Magnetic Energy Storage (SMES), flywheels, and batteries to improve grid reliability. Links to details on each technology.