This cluster includes science and engineering research into renewable energy technologies, including solar photovoltaics (PV), wind energy systems, biomass, energy storage, and hydrogen technologies as well as engineering and economics research applied to the electric power system. Much of the research on these topics is interdisciplinary, and integrates economics, operations research, and engineering to address the challenges in planning and operating the power system of the next century, in which many technologies and resources will be coordinated to efficiently and sustainably deliver energy.