  The Internet of Energy (IoE) is a distributed paradigm that leverages smart
networks and distributed system technologies to enable decentralized energy
systems. In contrast to the traditional centralized energy systems, distributed
Energy Internet systems comprise multiple components and communication
requirements that demand innovative technologies for decentralization,
reliability, efficiency, and security. Recent advances in blockchain
architectures, smart contracts, and distributed federated learning technologies
have opened up new opportunities for realizing decentralized Energy Internet
services. In this paper, we present a comprehensive analysis and classification
of state-of-the-art solutions that employ blockchain, smart contracts, and
federated learning for the IoE domains. Specifically, we identify four
representative system models and discuss their key aspects. These models
demonstrate the diverse ways in which blockchain, smart contracts, and
federated learning can be integrated to support the main domains of IoE, namely
distributed energy trading and sharing, smart microgrid energy networks, and
electric and connected vehicle management. Furthermore, we provide a detailed
comparison of the different levels of decentralization, the advantages of
federated learning, and the benefits of using blockchain for the IoE systems.
Additionally, we identify open issues and areas for future research for
integrating federated learning and blockchain in the Internet of Energy
domains.
