Energy sustainability and sustainable energy systems play a major role in the long-term sustenance of human existence and the environment, and improve the coexistence between technology and nature. Cyber-physical systems are one of the means for achieving energy sustainability. The physical layer comprising of power/energy and the cyber layer comprising of control, communication, and computation needs to be designed to achieve the overall goals of energy sustenance such as integration of renewable energy to the grid, reliable control power converters, microgrid control and protection, energy harvesting from nonconventional sources and efficient power circuit topologies. The confluence of the cyber and physical layers is seen in a multitude of applications such as smart connected and self-sustainable electronic grids; smart cities, centers, buildings, and villages; electronically controlled mobility, transportability, and energy transformation (e.g., electric vehicles and locomotives, electronically controlled semiconductor-based transformers); healthcare and biomedicine; cognitics, robotics, and wearables; lighting; telecommunications; aerospace, avionics, and space applications; off-grid and rural-electrification applications; and network-on chips, edge computing, and the Internet of Things (IoT).