Pumped hydro storage technology has existed as an energy storage technology for nearly a century in the United States and Europe. Modern energy storage technology as we know it today originated from the “Batteries for Specific Solar Applications” project launched in 1978 at Sandia National Laboratories, which focused on developing batteries and other renewable energy sources. Launched shortly after the formal establishment of the Department of Energy, the project expanded rapidly, focusing on electric vehicle batteries. Over time, the project (now known as the Energy Storage Systems Project, ESSP) has evolved to encompass other energy storage technologies such as flywheel storage and compressed air storage. While ESSP originated at Sandia National Laboratories, interdisciplinary collaborative research, ranging from materials science to energy storage technology demonstrations, continues at Argonne National Laboratory, Oak Ridge National Laboratory, and Pacific Northwest National Laboratory. The research findings from these laboratories continue to develop in the private sector and other independent private research areas, and will continue to evolve over time.