To achieving the future carbon neutrality, energy systems are under the transition with high renewable energy penetration. The flexibility of the energy systems becomes more important for dynamic balancing of supplies and demands. This lecture focuses on the challenges and opportunities associated with energy transitions, for example, spatial and temporal characterization of energy demand and renewable resources for urban district, smart intervention with the new technologies for consumers into prosumers, and integration of renewable energy with energy storage. We argue that the renewable industry has reached the tipping point of competitive costs. We call for accelerating and promoting market-based distributed energy technologies, energy storage, and smart integration of prosumers to respond energy transition.