# The Emerging Energy Internet: Architecture, Benefits, Challenges, and Future Prospects
## 1 Introduction
As the concept of EI involves energy transactions, a business perspective of EI involving multiple energy transaction stages has been discussed [16]. Different communication technologies along with standard communication protocols for EI is addressed in the literature [21]. Also, the security challenges involved with EI communication technology are discussed by the authors of [18]. In the literature [22], an architecture of a multilevel internet-aided microgrid system for interfacing distributed renewable energy resources with EI in a flexible manner is proposed. A solution for the peak load shifting problem and demand-side management with energy trading among the end-users of EI is given by the authors of [23]. Based on previous research works and the growing attention in this area, a thorough review for EI is required. This paper presents a review on EI, typically focusing on the different architectures of EI, as well as the models of energy routers (ER) employed for EI operations. Also, the challenges faced in EI implementation are discussed, and future prospects for EI are presented. The organization of this paper is as follows. Section 2 describes the concept and architecture of the energy Internet. The types of ERs employed in EI operation are explained in Section 3. The role of EI in the  
EI can be envisioned as an internetwork of distributed energy resources (i.e., DRERs and DESDs) combined with legacy power systems, and supporting communication through the Internet, as shown in Figure 1. The concept of EI is the next level of smart grids. EI is based on distributed energy resources that can act as prosumers. EI contains controllable loads powered by IOT, and operates them in different energy modes for optimizing energy flow. In the literature [18; 22], the authors proposed different architectures of EI. [PERSON] [26] discussed the architecture of EI, with a focus on the interactions among the agents (generation and transmission) in an economic prospective. However, their model lacks the integration of DRERs, the flexibility of supply (AC/DC) and communication between the end users, and utility. Furthermore, nowadays, consumers can have a variety of loads, such as battery charging for electric vehicles, or in the future, there may be a small DC nano-grid for some specific purpose [27]. Hence, the flexibility of the AC/DC supply is an important factor for EI architecture. [PERSON] et al. [22] focused extensively on the integration of diverse DRERs and DESDs in Future Renewable Electric Energy Delivery and Management (FREEDM) architecture, which is mainly based on the operation of the new generation of solid state transformers (SSTs). Among the different architectures, the FREEDM architecture of EI is the most commonly employed. This is due to the fact that it considers a flexible and distributed integration and management of DRERs and DESDs with the existing power system, making a stable and reliable microgrid structure. In order to achieve the realization of the EI architecture, this section covers the key components of the FREEDM architecture in detail.