Without energy storage, many alternative energy generation technologies, such as wind and solar, are limited to a supplemental role. Further, mobile energy storage (including energy carriers) is essential to utilizing alternative energy generation for transportation needs and portable devices. As such, we place energy storage as one of the major green technologies. The hallmarks of “green” energy storage technologies are typically very long equipment lifetimes and low environmental impact. Energy storage techniques such as pumped hydroelectric, flywheel, ultracapacitor, hydrogen, advanced battery technologies, and compressed air systems all show promise for substantially improved lifetime and/or reduced lifecycle environmental impact for differing stationary applications. Advanced battery technologies, flywheel, ultracapacitor systems, as well as generation of alternative fuels such as hydrogen, ethanol, methane, methanol, biodiesel can greatly improve environmental impact for mobile applications. In fact, energy generation and energy storage combinations are available today that meet all the requirements of sustainability, such that true green standalone systems can be implemented.