The penetration of renewable energy systems has been increasing globally. These intermittent renewable energy resources require additional power system resources to balance the fluctuations in both loads and intermittent generators. The additional system resources have traditionally been supplied by dispatchable central generation stations, some are fossil fuel based. However, this is unsustainable due to the high environmental impacts. Various energy storage systems using pumped hydro, compressed air, battery, flywheel and hydrogen systems as sources have been applied in utilities. In addition to other limitations, costs are still high for these available energy storage systems in utility applications. Dr. Liuchen Chang will present an alternative energy storage resource for power systems based on distributed energy resources including aggregated direct control of electrical loads. These loads have thermal energy storage capacities, including water heaters, electrical thermal storage units, ice making units, HVACs, etc. With aggregated controls and virtual power plants, the overall power consumed by these loads can be ramped up or ramped down continuously without negative impact to the normal end use, similarly to other forms of energy storage systems. Distributed generation systems, energy storage systems, and direct load control systems as in the portfolio of distributed energy resources thus form generalized energy storage systems as new and alternative power system resources, which will enable integration of more intermittent renewable energy systems in utilities. Dr. Chang will also introduce the IEEE International Technology Roadmap of Power Electronics for Distributed Energy Resources (IRTD).