In this paper, we have comprehensively analyzed Internet of Things (IoT) applications enabled for smart grids and smart environments, such as smart cities, smart homes, smart metering, and energy management infrastructures to investigate the development of the EI based. In this paper, we have comprehensively analyzed Internet of Things (IoT) applications enabled for smart grids and smart environments, such as smart cities, smart homes, smart metering, and energy management infrastructures to investigate the development of the EI based. It is the most influential annual academic event in the field of global Energy Internet. The 9th IEEE Conference on Energy Internet and Energy System Integration (IEEE EI² 2025), organized by IEEE Power and Energy Society, Chinese Society for Electrical Engineering, Northeast Electric Power. Energy Internet (EI) has been recently introduced as a new concept, which aims to evolve smart grids by integrating several energy forms into an extremely flexible and effective grid. The current scope of IoT in the energy sector focuses on enhancing efficiency, reducing operational costs, and implementing more intelligent energy. The application of the Internet of Things (IoT) in energy infrastructure is revolutionizing operations and maintenance practices, driving efficiencies, and enhancing sustainability across the sector. Denmark, renowned for its leadership in wind energy, employs cutting-edge.